Provided by: k2pdfopt_2.51+ds-1_amd64 bug

NAME

       K2pdfopt - PDF Reflow tool

SYNOPSIS

       k2pdfopt [opts] <input pdf/djvu | folder>

DESCRIPTION

       K2pdfopt attempts to optimize PDF (or DJVU) files (especially two-column ones) for display
       on the Kindle (or other mobile readers/smartphones) by looking for rectangular regions  in
       the  file and re-paginating them without margins and excess white space.  Works on any PDF
       or DJVU (.djvu) file, but assumes it has a mostly-white background.  Native PDF files (not
       scanned) work best.

       If  given  a  folder, k2pdfopt first looks for bitmaps in the folder and if any are found,
       converts those bitmaps to a PDF as if they were pages of a PDF  file.   If  there  are  no
       bitmaps  in  the  folder  and  if  PDF files are in the folder, then each PDF file will be
       converted in sequence.

       Output files are always .pdf and have _k2opt added to the source name by default  (see  -o
       option to specify alternate output name.)

Environment variable

       You can supply command-line options via the environment variable K2PDFOPT, for example,

              set K2PDFOPT=-ui- -x -j 0 -m 0.25

       Command  line  options  from  the  command  line  take  precedence  over  the  ones in the
       environment variable K2PDFOPT.

OPTIONS

       You may not have to read this manual -  run  k2pdfopt  without  any  option  and  use  the
       interactive menu to select desired options.

       -?[-] [pattern]
              Show [don't show] usage only (no file processing).

              If  pattern  is  specified,  only options with text matching the pattern are shown.
              The pattern can use * as a wild card, e.g. -? -col.  Use -?-  to  turn  off  usage.
              Combine with -ui- to get something you can redirect to a file.

       -a[-]  Turn  on  [off]  text  coloring  (use  of  ANSI  color codes) on the screen output.
              Default is on.

       -ac[-] [<aggressiveness>]
              Auto crop.  For books or papers that have dark edges due to copying artifacts, this
              option  will  attempt to automatically crop out those dark regions so that k2pdfopt
              can correctly process the source file.  The <aggressiveness> factor is from 0 to 1.
              Higher is more aggressive cropping.

              Default if not specified is 0.1.  See also -m.

              Default value is off (-ac-).

              Note  that  autocropping  does not work on cropped regions created with -cbox.  See
              -dw for a discussion about this.

       -as[-] [<maxdeg>]
              Attempt to automatically straighten tilted source pages.

              Will rotate up to +/-<maxdegrees>  degrees  if  a  value  is  specified,  otherwise
              defaults  to  4  degrees max.  Use -1 to turn off. Default is off (-as -1 or -as-).
              Note that autostraighten does not work on cropped regions.

              See -dw for a discussion about this.

       -author <author>
              Set the author metadata / property of the PDF output file(s). Default is to use the
              author of the source document (-author "").

       -bmp[-] <pageno>
              Generate [do not generate] a bitmap rendering of converted page number <pageno> and
              write it to file k2pdfopt_out.png.  If this option is  used,  no  other  files  are
              written, i.e. the complete conversion is NOT done--ONLY the bitmap file is written.
              If -sm is also specified, then the bitmap is of marked source  page  <pageno>.   If
              -bmp-, then <pageno> is not necessary.  Default is -bmp-.

       -bp[+|-|--] [m|<inches>]
              Break [do not break] output pages at end of each input page.

              Default  is  -bp-.   If a numeric value is put after -bp, then rather than breaking
              the output page at the end of each input page, a  gap  is  inserted  of  that  many
              inches,  e.g.   -bp 1 will insert a 1-inch gap between contents of each input page.
              Special option -bp+ will break the pages at the green boundaries between region  as
              marked  by the -sm option (see -sm).  If bookmark information is available and -toc
              is specified (on by default) page breaks will be inserted in the converted file  at
              each  bookmark  unless  -bp--  is  specified.  If "-bp m" is specified, then a page
              break is inserted after each major (red-box) section.  This can help  prevent  text
              selection overlap problems in native output mode.  See also -toc, -bpl.

       -bpc <nn>
              Set  the  bits per color plane on the output device to <nn>.  The value of <nn> can
              be 1, 2, 4, or 8.  The default is 4 to match the kindle's display capability.  This
              is ignored if the -jpg option is specified.

       -bpl <srcpagelist>
              Insert  page  break  in  destination  file  before  each source file page listed in
              <srcpagelist>.  This has the same format as the -p option.  See also -p, -bp, -toc,
              -toclist.  Default is no page list.  Example:  -bpl 10,25,50,70,93,117,143.

              This automatically sets -bp to it's default value (-bp-).

       -bpm[<type>] <color>
              Set  a page break mark type and color.  This option allows you to put colored marks
              in the PDF file to specify where to break pages or  where  to  avoid  page  breaks.
              <type>  is  either  1 to force a page break or 2 to prevent a page break until next
              mark.  <color> is an R,G,B triplet, 0-1 for each color component, no  spaces.   For
              example,  to break the page wherever the source file has a green dot or short green
              horizontal line:  -bpm1 0,1,0.  Use <color> = -1 to clear.  If you omit the <type>,
              1 is assumed.

       -c[-]  Output in color [grayscale].  Default is grayscale.

       -cbox[<pagelist>|u|-] <cropbox>
              Similar  to  the  -grid option, but allows you to specify exact crop boxes from the
              source page which will then be processed as major (red-box) regions.  These regions
              can  then  become individual output pages or can be processed further (searched for
              columns, re-flowed, etc.)  depending  on  what  other  options  are  selected.   By
              default, they are processed further, like every other major region.

              You may specify the -cbox option multiple times to crop out different parts of each
              source page, each crop being treated as a major region.  See the -mode command.  To
              have  each  crop  box  become a new page in the output file, for example, use -mode
              crop, e.g.

                     k2pdfopt myfile.pdf -mode crop -cbox 2in,3in

              <cropbox>  has  the  format  <left>,<top>,<width>,<height>  where  all  values  are
              specified  from  the  upper-left corner of the source page, with units, like the -w
              and -h options, except that the default units for -cbox are inches.  If only <left>
              and <top> are specified, then <width> and <height> extend to the edge of the page.

              Example:
              -cbox 1in,1in,6in,9in
              (same as -cbox 1,1,6,9).

                     This  specifies  a crop box that is 6 x 9 inches and which has an upper left
                     corner which is 1 inch from the left and top of the source page.

              Use -cbox- to clear all cropboxes, which defaults back  to  processing  every  page
              without any crop boxes.

              You  can  use  a  page  list,  <pagelist>,  to  specify on which pages to apply the
              cropboxes.

              Examples:

                     -cbox5-51o
                            applies the cropbox on pages 5,7,9,...,51.

                            ('o' = odd.  Use 'e' for even.)

                     -cbox1,2-5,13,15
                            applies the cropbox on pages 1,2,3,4,5,13, and 15.

                     -cboxc <cropbox>
                            applies <cropbox> to the cover image.

                            (see -ci option.)

              Be sure not to put a space between -cbox and the page list.

              Use -cboxu to set a crop box for all unspecified pages.

              E.g. -cbox1-10 <cbox1> -cboxu <cbox2> will apply <cbox1> to all pages 1 to  10  and
              <cbox2> to all other pages.

              The default is no crop boxes (-cbox-).  See also -m, -ac.

              USAGE  NOTE:   Once  you  specify  -cbox at least one time, only the crop boxes you
              specify (and any associated page ranges) are processed/converted by  k2pdfopt.   No
              other  pages or regions are processed.  So if you want to specify a special cropbox
              for the first page,  for  example,  but  then  have  all  remaining  pages  treated
              entirely, you must specify this:

                     -cbox1 ... -cboxu 0,0

                     (-cboxu 0,0 applies a full-page cropbox to all other
                       pages.  u = unspecified.)

              The -cbox2- 0,0 will set the cropbox for pages 2 and beyond to the full page size.

              See also:  -ibox.

       -cg <inches>
              Minimum  column  gap width in inches for detecting multiple columns.  Default = 0.1
              inches.  Setting this too large will give very poor results for multicolumn  files.
              See also -cgmax.

       -cgmax <inches>
              Max  allowed gap between columns in inches.  If the gap between two regions exceeds
              this value, they will not be considered as separate columns.  Default =  1.5.   Use
              -1 for no limit (disable).  See also -cg.

       -cgr <range>
              Set column-gap range, 0 - 1.  This is the horizontal range over which k2pdfopt will
              search for a column gap, as a fraction of the  page  width.   E.g.  -cgr  0.5  will
              search from 0.25 to 0.75 of the page width for a column gap.

              Set  this  to  a  small  value,  e.g. 0.05, to only search for column breaks in the
              middle of the page.  Default = 0.33.

       -ch <inches>
              Minimum column height in inches for detecting  multiple  columns.   Default  =  1.5
              inches.

       -ci[-] <imagefile>
              Specify  a cover image for the first page of the converted PDF.  <imagefile> can be
              a bitmap file (png or jpg) or can be a page from a PDF  file,  e.g.  myfile.pdf[34]
              would  use  page 34 of myfile.pdf.  You can just specify an integer, e.g. -ci 50 to
              use page 50 of the source file being converted as the cover page.  Default is -ci-,
              which is no cover image.

              NOTE:  -ci only works with bitmapped output--it does not (yet) work with native PDF
                     output.

       -cmax <max>
              Set max contrast increase on source pages.  1.0 keeps contrast from being adjusted.
              Use a negative value to specify a fixed contrast adjustment.  Def = 2.0.

              See also -er.

       -col <maxcol>
              Set max number of columns.  <maxcol> can be 1, 2, or 4.  Default is -col 2.  -col 1
              disables column searching.

       -colorbg (or -colorfg) <hexcolor>|<bitmap>[,<hexcolor>|<bitmap>[,...]]
              Map the color white (background color, for  -colorbg)  or  the  color  black  (text
              color,  for  -colorfg)  to  <hexcolor>,  where  <hexcolor>  is a 6-digit hex RRGGBB
              representation of a color, e.g. ffffff for all white, 000000 for all black,  ff0000
              for bright red, etc.  If <hexcolor> is not a grayscale color, the -c (color output)
              option will be turned on automatically.  This  option  only  works  with  bitmapped
              output  (not  native--see  -n).   Grayscale  colors between black and white will be
              linearly interpolated between the specified -colorbg and -colorfg colors.   If  the
              source document has colors, only (mostly) grayscale pixels are affected if ! is put
              before the color, e.g. -colorbg !ffffd0

              A bitmap can also be specified, e.g. -colorbg myfile.jpg.  In this case, the bitmap
              gets tiled in as the background.

              If you specify a comma delimited list of colors (or bitmaps), then consecutive rows
              of text are colored with the consecutive colors.  This is a possible  way  to  make
              the  rows  of  text  easier to follow, e.g. -colorfg ff0000,00 will color alternate
              rows of text red and black.

              Default is -colorbg "" and -colorfg "" (no mappings).

       -comax <range>
              Stands for Column Offset Maximum.  The <range> given is as a fraction of the  width
              of  a  single  column, and it specifies how much the column divider can move around
              and still have the columns considered contiguous.  Set to -1 to revert back to  how
              columns were treated in k2pdfopt v1.34 and before.

              Default = 0.3.

       -crgh <inches>
              Set  the min height of the blank area that separates regions with different numbers
              of columns.

              Default = 1/72 inch.

       -d[-]  Turn on [off] dithering for bpc values < 8.  See -bpc.

              Default is on.

       -de <size>
              Defect size in points.  For scanned documents, marks or defects smaller  than  this
              size  are  ignored  when  bounding rectangular regions.  The period at the end of a
              sentence is typically over 1 point in size.  The default is 1.0.

       -dev <name>
              Select device profile (sets width, height, dpi, and  corner  marking  for  selected
              devices).   Currently  the  selection  is  limited.  <name> just has to have enough
              characters to uniquely pick the device.  Use -dev ? to list the devices.

              Default is -dev kindle2.

       -dpi <dpival>
              Same as -odpi.

       -dr <value>
              Display resolution multiplier.  Default = 1.0.  Using a value greater than 1 should
              improve the resolution of the output file (but will make it larger in file size).

              E.g. -dr 2 will double the output DPI, the device width (in pixels), and the device
              height (in pixels).

       -ds <factor>
              Override the document size with a scale factor.  E.g. if your PDF reader  says  the
              PDF  file is 17 x 22 inches and it should actually be 8.5 x 11 inches, use -ds 0.5.
              Default is 1.0.

       -dw[-] [<fitorder>]
              De-warp [do not de-warp] pages (uses Leptonica de-warp algorithms).  Default is not
              to  de-warp.   Does not work for native mode output.  Optional <fitorder> specifies
              the fit order for the dewarping curves.  Can be 2, 3, or 4.

              Default is 4.

              [Advanced: You can actually make the fit order a two-digit code.  E.g. -dw 24  will
              use  4th-order  on  each row of text but only 2nd-order for columns of displacement
              (see leptonica dewarpFindVertDisparity() in dewarp2.c)]

              Note: de-warping, like auto-straighten and auto-crop, is intended for entire pages.
              It  does  not  work on cropped areas.  If you want it to work on cropped areas, you
              should run k2pdfopt in two passes--first to create selected crop areas (e.g.  -mode
              crop), then to apply dewarping.

              Require k2pdfopt built with leptonica.

       -ehl <n>
              Same  as -evl, except erases horizontal lines instead of vertical lines.  See -evl.
              Default is -ehl 0.

       -er <n>
              Use erosion filter on source bitmaps.  Makes the text look darker.  A larger  value
              of  <n>  makes  the  text  thicker/darker.   Try  -er 1 or -er 2.  Default is 0 (no
              erosion filtering).

              Use a negative value for <n> to do the erosion before the constrast  adjustment  is
              applied.   Use a positive value to to the erosion after the constrast adjustment is
              applied.  This option may magnify scanning defects, so you might  want  to  combine
              with the -de (defect removal) option.

              Has no effect in native mode output. See also -de, -g, -cmax.

       -evl <n>
              Detects  and  erases  vertical  lines  in  the source document which may be keeping
              k2pdfopt from correctly separating columns or wrapping text, e.g. column  dividers.
              If  <n> is zero, this is turned off (the default).  If <n> is 1, only free-standing
              vertical lines are removed.  If <n> is 2, vertical lines are erased  even  if  they
              are the sides of an enclosed rectangle or figure, for example.

       -f2p <val>
              Fit-to-page  option.   The quantity <val> controls fitting tall or small contiguous
              objects (like figures or photographs) to the device screen.  Normally these are fit
              to  the  width  of  the  device,  but  if  they  are too small or too tall, then if
              <val>=10, for example, they are allowed to be 10% wider (if too small) or  narrower
              (if  too tall) than the screen in order to fit better.  Use -1 to fit the object no
              matter what.  Use -2 as a special case--all "red-boxed" regions  (see  -sm  option)
              are placed one per page.

              Use  -f2p  -3  to  fit as many "red-boxed" regions as possible on each page without
              breaking them across pages.  (see -mode concat).

              Default is -f2p 0.  See also -jf, -fr.

              Note:  -f2p -2 will automatically also set -vb -2 to exactly preserve  the  spacing
              in  the  red-boxed  region.   If  you  want to compress the vertical spacing in the
              red-boxed region, use -f2p -2 -vb -1.

       -fc[-] For multiple column documents, fit [don't fit] columns to the width of  the  reader
              screen regardless of -odpi.

              Default is to fit the columns to the reader.

       -fr[-] Figure rotate--rotates wide-aspect-ratio figures to landscape so that they best fit
              on the reader page.  Default is not to rotate.  See also -f2p.

       -fs <points>[+]
              The output document is scaled so that the median font size in the converted file is
              <points>  points.   If  the  <points>  value  is  followed by a '+', the scaling is
              adjusted for every source page, otherwise the font  size  is  only  adjusted  once,
              based  on  the median font size for the entire source document.  The default is -fs
              0, which turns off scaling based on font size.  The use of -fs overrides  the  -mag
              setting.

       -g <gamma>
              Set  gamma value of output bitmaps. A value less than 1.0 makes the page darker and
              may make the font more readable.  Default is 0.5.  Has no effect  with  native-mode
              output.  See also -er, -cmax.

       -grid <C>x<R>[x<O>][+]
              Grid  the  source  page into <C> columns by <R> rows with with <O> percent overlap.
              No regard will be made for trying to break the page  between  columns  or  rows  of
              text.   If  a  +  is  specified, the destination page order will go across and then
              down, otherwise it will go down and then across.  To turn off gridding,  specify  a
              zero  value  for the columns or for the rows.  Default is no gridding.  The default
              overlap is 2%.   Example:   -grid  2x2x5.   By  default,  gridding  also  sets  the
              following  options, which can be overridden by following the grid option with other
              command options: -n -wrap- -f2p -2 -vb -2 -col 1.   For  example,  if  you  want  a
              column  search  done  on  each grid piece, you can put this: -grid 2x2 -col 2.  See
              also -cbox.

       -gs[-][-]
              Force use of Ghostscript instead of MuPDF to read PDFs.  K2pdfopt has built-in  PDF
              translation  (via the MuPDF library) but will try to use Ghostscript if Ghostscript
              is available and the internal (MuPDF) translation fails (virtually never  happens).
              You  can  force  Ghostscript  to  be  used  with  this -gs option.  Use -gs- to use
              Ghostscript only if MuPDF fails.  Use -gs-- to  never  use  Ghostscript.   Download
              ghostscript at http://www.ghostscript.com.

       -gtc <inches>
              Threshold  value  for  detecting  column  gaps (expert mode).  Sets how many of the
              pixels in the column shaft can be non-white (total height of a  line  crossing  the
              shaft in inches).  See also -gtr.  Default = .005.

       -gtr <inches>
              Threshold  for  detecting  gaps  between rows (expert mode).  This sets the maximum
              total black pixels, in inches, on average, that can be in each row of pixels before
              the  gap  is  no longer considered a gap.  A higher value makes it easier to detect
              gaps between rows of text.  Too high of a value may inadvertently split figures and
              other graphics.

              Default = 0.006.  See also -rsf.

       -gtw <inches>
              Threshold for detecting word gaps (expert mode).

              See -gtr.  Default = .0015.

       -gui[-]
              Use [don't use] graphical user interface (MS Windows only).  If k2pdfopt is started
              from a console (command-line), the default is not to launch the  gui  unless  there
              are no command- line options given.  If k2pdfopt is launched via its icon, then the
              default is to launch the GUI.

       -guimin[-]
              Start the k2pdfopt GUI minimized.  Def = not minimized.

       -h <height>[in|cm|s|t|p|x]
              Set height of output device in pixels, inches, cm, source page  size  (s),  trimmed
              source region size (t), pixels (p), or relative to the OCR text layer (x).

              The  default  units are pixels (p), and the default value is 735 (the height of the
              Kindle 2 screen in pixels).

              Examples:

                        -h 6.5in
                               Sets the device height to 6.5 in (using the output dpi to  convert
                               to pixels--see -dpi).

                        -h 1.5s
                               Sets  the  device height to 1.5 times the source page height (same
                               as -h -1.5).

                        -h 1t  Sets the device height to whatever the trimmed page height is (you
                               can  follow  -mode  copy with -h 1t to make the output page height
                               equal to the crop box height.

                        -h 0.5x
                               Sets the device height to half of the height of  the  box  exactly
                               surrounding the OCR text layer on the source page.

              See also -w, -dpi, -dr.

       -hy[-] Turn on [off] hyphen detection/elimination when wrapping text.  Default is on.

       -i     Echo information about the source file (PDF only).

              Disables all other processing.

       -ibox[<pagelist>|-|u] <cropbox>
              Same  as  -cbox (see -cbox), except that these boxes are ignored by k2pdfopt.  This
              is done by whiting out the boxes in the source bitmap.  For native output, the area
              in  the  -ibox  will not affect the parsing of the source file, but it may still be
              visible in the output file.  Default is no iboxes (-ibox-).  See also -cbox.

       -idpi <dpi>
              Set pixels per inch for input file.  Use a negative value as a  multiplier  on  the
              output  dpi  (e.g. -2 will set the input file dpi to twice the output file dpi (see
              -odpi).  Default is -2.0.

       -j -1|0|1|2[+/-]
              Set output text justification.  0 = left, 1 = center,  2  =  right.   Add  a  +  to
              attempt  full  justification  or a - to explicitly turn it off.  The default is -1,
              which tells k2pdfopt to try and maintain the justification of the  document  as  it
              is.  See also -wrap.

       -jf 0|1|2 [<inches>]
              Set  figure  (tall  region)  justification.   If a figure has left or right margins
              available, this option allows you to set the  justification  differently  than  the
              text.   E.g.  you  can center figures with -jf 1.  If you want to specify a minimum
              height for figures (e.g. minimum region height where this  justification  applies),
              you  can tack it on at the end, e.g. -jf 1 1.5 to center any region taller than 1.5
              inches.  Default is 0.75 inches  for  the  minimum  height  and  to  use  the  same
              justification  on  figures  as the rest of the document (-jf -1).  See also -f2p to
              fit small or tall figures to the page.

       -jfc[-|+]
              Attempt [do not attempt] to keep figure captions joined with their figures.  If you
              specify  -jfc+,  k2pdfopt  will  also try to detect figure captions in multi-column
              documents.  This is not done by default because k2pdfopt will sometimes (more often
              than  not,  in  my  experience) incorrectly choose the multi-column layout if it is
              also trying to detect what is a figure caption.  See also -cg, -cgmax, -cgr, -crgh.
              Default = -jfc.

       -jpg [<quality>]
              Use  JPEG  compression  in PDF file with quality level <quality> (def=90).  A lower
              quality value will make  your  file  smaller.   See  also  -png.  Use  of  -jpg  is
              incompatible with the -bpc option.

       -l <lang>
              See -ocrlang.

       -lang <lang>
              See -ocrlang.

       -ls[-][pagelist]
              Set output to be in landscape [portrait] mode.  The default is -ls- (portrait).  If
              an optional pagelist is specified, only those pages are affected--any  other  pages
              are  done  oppositely.  E.g. -ls1,3,5-10 would make source pages 1, 3 and 5 through
              10 landscape.

       -m[l|t|r|b] <val>[<units>][,<val>[units][,...]]
              Set global crop  margins  for  every  page.   If  more  than  one  value  is  given
              (comma-delimited with no spaces in between), the order is left, top, right, bottom,
              e.g. -m <left>,<top>,<right>,<bottom>.  You can also use the  more  powerful  -cbox
              option  to  do this same thing.  The default units are inches.  For available units
              and their descriptions, see -h.

              Examples:

              -m 0.5cm
                     Sets all margins to 0.5 cm.

              -m 0.5cm,1.0cm
                     Sets the left margin to 0.5 cm and all the other margins to 1.0 cm.

              -m 0.2in,0.5in,0.2in,0.5in
                     Sets the left and right crop margins to 0.2 inches and the top and bottom to
                     0.5 inches.

              -mt 1cm
                     Sets the top margin to 0.5 cm.

              -m -0.1x,-0.1x,1.1x,1.1x
                     With  the  'x'  unit,  the  behavior  is  a  little  different.  Rather than
                     specifying the widths of each margin, you specify the position of  the  crop
                     box  relative  to  the  OCR text layer in the source file, where 0x,0x,1x,1x
                     would exactly bound the OCR text layer.

              The default crop margins are 0 inches.

              [NOTE: The default was 0.25 inches for all margins before v1.65.]

              See also -cbox and -ac to autocrop scanning artifacts.

       -mag <value>
              Magnify the converted document (text) size by  <value>.   Default  is  -mag  1  (no
              magnification). See also -fs.

       -mc[-] Mark  [don't  mark]  corners  of the output bitmaps with a small dot to prevent the
              reading device from re-scaling.  Default = mark.

       -mode <mode>
              Shortcut for setting multiple options at once which  determine  the  basic  way  in
              which k2pdfopt will behave.

              Available modes are:

              copy   Same  as  -n- -wrap- -col 1 -vb -2 -w 1s -h 1s -dpi 150 -rt 0 -c -t- -f2p -2
                     -m 0 -om 0 -pl 0 -pr 0 -pt 0 -pb 0 -mc-.  Makes k2pdfopt behave exactly like
                     my  pdfr  program--source  pages  are  simply copied to the output file, but
                     rendered as bitmaps.  No trimming or re-sizing is done.  Can also use  -mode
                     pdfr.

                     Note  1:   Use  -mode  copy  -n  if you want an exact copy (output in native
                            mode).

                     Note 2:  The default gamma and contrast settings  are  not  reset  by  -mode
                            copy.  If you want a perfect copy, do this:
                                   -mode copy -gamma 1 -cmax 1

              fp     Also can use fitpage.  Same as -n -wrap- -col 1 -vb -2 -f2p -2 -t.

              fw     Same  as -n -wrap- -col 1 -vb -2 -t -ls.  Makes k2pdfopt behave like sopdf's
                     "fit width" option.  Can also use -mode sopdf.

              2col   Same as -n -wrap- -col 2 -vb -2 -t.  Optimizes  for  a  2-column  scientific
                     article with native PDF output.

              tm     Trim  margins--same  as -mode copy, but sets the output to be trimmed to the
                     margins and the width and height of the output to match the  trimmed  source
                     pages.   Also  uses native mode.  Equivalent to -n -wrap- -col 1 -vb -2 -f2p
                     -2 -t -w 1t -h 1t -rt 0 -c -m 0 -om 0 -pl 0 -pr 0 -pt 0  -pb  0  -mc-.   Can
                     also use -mode trim.

              crop   Used  with  -cbox  option,  puts  each  cropped  area  on  a  separate page,
                     untrimmed, and sizes the page to the cropped region.  Same as -wrap- -col  1
                     -vb  -2  -w  1t  -h 1t -t- -rt 0 -c -f2p -2 -m 0 -om 0 -pad 0 -mc- -n concat
                     Keeping the output pages the same size as the  source  pages,  fit  as  many
                     crop-boxed  regions  on  the  output pages as possible without breaking them
                     across pages.  Equivalent to: -n -wrap- -col 1 -vb -2 -t- -f2p -3 -fc- -w 1s
                     -h  1s  -ocrdef     Default k2pdfopt mode: -wrap -n- -col 2 -vb 1.75 -dev k2
                     -rt auto -c- -t -f2p 0 -m 0 -om 0.02 -ls-.

              concat Keeping the output pages the same size as the  source  pages,  fit  as  many
                     crop-boxed regions  on  the  output  pages as possible without breaking them
                     across pages.  Equivalent to: -n -wrap- -col 1 -vb -2 -t- -f2p -3 -fc- -w 1s

                     -h 1s -ocr-
              def    Default  k2pdfopt  mode:  -wrap  -n- -col 2 -vb 1.75 -dev k2 -rt auto -c- -t
                     -f2p 0 -m 0 -om 0.02 -ls-.

              You can modify modes by overriding their options after specifying  the  mode,  e.g.
              -mode fw -vb -1.

       -n[-]  Use "native" PDF output format.  NOTE: if you want native PDF output, it's probably
              best to use a -mode option like  -mode  fitwidth  or  -mode  2col,  both  of  which
              automatically turn on native PDF output and optimize other settings for it.  Native
              PDF output preserves the native source PDF contents, i.e. the output  PDF  file  is
              not  rendered  as a sequence of bitmapped pages like in the default k2pdfopt output
              mode.  Instead, the source PDF's native content is used along with  additional  PDF
              instructions  to  translate,  scale,  and crop the source content.  With native PDF
              output, if the source file has selectable text, the text remains selectable in  the
              output  file.   The  output file can also be zoomed without loss of fidelity.  This
              may also result in a smaller output file (but not always).  By default, native  PDF
              output format is turned off.  See also -mode.

              NOTES:

              1.     Native  PDF  output cannot be used with text wrapping on (see -wrap option).
                     Turning it on will disable text wrapping.

              2.     Native PDF output is not recommended for  source  files  which  are  scanned
                     (there  is  no  benefit  unless the scanned document includes a layer of OCR
                     text).

              3.     Native PDF output is  incompatible  with  OCR  (see  -ocr),  though  OCR  is
                     typically  not  necessary  if  the native PDF contents are kept.  Turning on
                     native PDF output will disable OCR.

              4.     Native PDF output can only be used with PDF source files (it does  not  work
                     with DJVU source files).

              5.     Contrast  adjust,  gamma correction, and sharpening are disabled with native
                     PDF output.

              6.     It is recommended that you use -vb -2 with native PDF  output,  particularly
                     if  you  are  having  difficulty  selecting/searching text in the output PDF
                     file.

              7.     This option works well with -mode fw, -mode 2col, or with the -grid  option.
                     It is used by default in those cases.

       -neg[-|+]
              Inverse  [don't  inverse]  the output images (white letters on black background, or
              "night mode").  If -neg+, inverts all graphics  no  matter  what.   If  just  -neg,
              attempts to invert text only and not figures.  Default = -neg-.

              See also -colorbg and -colorfg.

       -ng <gap>
              Set  gap between notes and main text in the output document.  The <gap> defaults to
              inches but can have other units (see -h, for example).  See -nl and -nr for how  to
              turn on notes processing.  Default is -ng 0.2.

       -nl[<pages>] [<leftbound>,<rightbound>]

       -nr[<pages>] [<leftbound>,<rightbound>]
              The  source  document has notes in the left (-nl) or right (-nr) margins.  Specific
              pages can be specified for the notes using <pages> (same format as  -cbox  or  -p).
              If  <leftbound>,<rightbound>  are  specified, they specify the fraction of the page
              width where to look for the break between the notes and the main page.   E.g.   -nl
              0.15,0.25 will look for the boundary between the notes and the text between 15% and
              25% of the way across the source page.  Use -nl- to  turn  off  all  processing  of
              notes  in  the  margins (default).  Default values for <leftbound> and <rightbound>
              are 0.05 to 0.35 for -nl and 0.65 to 0.95 for -nr.

              Notes in the margins are treated differently than other "columns" of  text.    They
              will  be interspersed with the text in the adjacent column of main text.  Note that
              -nr... or -nl... will also set -cg to 0.05.

       -nt <nthreads>
              Use <nthreads> parallel threads when OCR-ing a  document  with  the  Tesseract  OCR
              engine  (GOCR is not thread safe).  This may provide a significant processing speed
              improvement when using Tesseract OCR.  Note that a  higher  number  is  not  always
              faster.   You  should  experiment with your system to find the optimum.  A negative
              value is interpreted as a percentage of available CPUs.  The default is -50,  which
              tells  k2pdfopt  to  use  half  of  the available CPU threads.  Some performances I
              measured:
              ----------------------------------------------------------
                                                           OCR Speed
                 O/S           CPU         Nthreads       improvement
              ----------------------------------------------------------
              Win 10 x64     Core i5      2 (default)        1.5x
              Win 10 x64     Core i5          3              1.6x
              Win 10 x64     Core i5          4              1.8x
              ----------------------------------------------------------
              Win 10 x64     Core i7          2              1.8x
              Win 10 x64     Core i7          3              2.4x
              Win 10 x64     Core i7      4 (default)        2.5x
              Win 10 x64     Core i7          5              2.8x
              Win 10 x64     Core i7          6              2.7x
              Win 10 x64     Core i7          7              2.7x
              Win 10 x64     Core i7          8              2.6x
              ----------------------------------------------------------
              Linux x64      Core i5      2 (default)        1.9x
              Linux x64      Core i5          3              2.6x
              Linux x64      Core i5          4              2.7x
              ----------------------------------------------------------
              Linux x64   Xeon E52690v2       2              1.9x
              Linux x64   Xeon E52690v2       4              3.5x
              Linux x64   Xeon E52690v2       6              5.1x
              Linux x64   Xeon E52690v2       8              6.6x
              Linux x64   Xeon E52690v2   10 (default)       8.7x
              Linux x64   Xeon E52690v2      14              9.5x
              Linux x64   Xeon E52690v2      20             10.2x
              ----------------------------------------------------------
              Interestingly, Linux seems to have  much  better  multithreading  performance  than
              Windows.  I suspect the OS/X results are similar to the Linux results.

              NOTE:  -nt has no effect if you select -ocrd c or -ocrd p.  See -ocrd.

              Require k2pdfopt built with OCR lib.

       -o <namefmt>
              Set  the  output file name using <namefmt>.  %s will be replaced with the full name
              of the source file minus the extension.  %b will be replaced by the  base  name  of
              the  source  file minus the extension.  %f will be replaced with the folder name of
              the source file.  %d will be replaced with the source file count (starting with 1).
              The  .pdf  extension  will  be appended if you don't specify an extension.  E.g. -o
              out%04d.pdf will result in output  files  out0001.pdf,  out0002.pdf,  ...  for  the
              converted files.  Def = %s_k2opt

              -------------------------------------------------------------

              BITMAP  OUTPUT:   For  output to bitmaps, you can put -o .png or -o .jpg (see -jpeg
              for quality setting).

              -------------------------------------------------------------

              MORE DETAIL:  If <namefmt> ends in .jpg or .png, the output will be in the JPEG  or
              PNG  bitmap format, respectively, one bitmap per page.  If your <namefmt> has no %d
              in it, then %04d will be appended.  If <namefmt> has  only  one  %d,  it  will  get
              substituted  with the page number.  If it has two %d's, the first will get the file
              count and the second will get the page number.   Example:  if  the  source  PDF  is
              myfile.pdf, then -o %s%03d.png would create myfile001.png, myfile002.png, etc., for
              each page of the PDF.

       -ocr[-][g|t|m]
              Attempt [don't attempt] to use optical character  recognition  (OCR)  in  order  to
              embed  searchable  text  into  the  output  PDF  document.   If followed by t or g,
              specifies the ocr engine to use (tesseract or gocr).  If followed by m, and if  the
              PDF  document  has  text  in  it, then the MuPDF engine is used to extract the text
              (sort of a virtual OCR).  If -ocr is specified with no argument, tesseract is used.
              If  tesseract  fails  (e.g.  no  language  files found), GOCR is used.  The overall
              default operation of k2pdfopt is -ocr m.  See also -ocrvis and -ocrhmax.

              NOTE:  Turning on OCR will disable native PDF output.

              DISCLAIMER:  The main intent of OCR isn't to improve the visual quality of the text
                  at  all--at  least not the way k2pdfopt does it.  OCR is most useful on scanned
                  PDFs that don't have selectable text to begin with, but using OCR with k2pdfopt
                  on  such  documents doesn't change the look of the output PDF file at all.  The
                  OCR text is simply placed invisibly over the scanned text so that you appear to
                  be  able  to  select  the  scanned  text  (when, in fact, you are selecting the
                  invisibly placed OCR text).  So the only time you  will  even  notice  the  OCR
                  errors  is if you try to search for a word and can't find that word because the
                  OCR of that word is incorrect, or if you copy a selection of the OCR  text  and
                  paste it into something else so that you can actually see it.

       -ocrcol <n>
              If  you are simply processing a PDF to OCR it (e.g. if you are using the -mode copy
              option) and the source document has multiple columns of text, set this value to the
              number of columns to process (up to 4).  Default is to use the same value as -col.

       -ocrd w|l|c|p

              Set  OCR  detection  type for k2pdfopt and Tesseract.  <type> can be word (w), line
              (l), columns (c), or page (p).  Default is line.

              For -ocrd w, k2pdfopt  locates  each  word  in  the  scanned  document  and  passes
              individual  words  to  Tesseract  for  OCR  conversion.   This was the only type of
              detection before v2.42 but is not an  optimal  OCR  conversion  method  when  using
              Tesseract.

              For  -ocrd  l,  k2pdfopt  passes  each  line of the converted file to Tesseract for
              conversion.  This typically gives better results than -ocrd w since  Tesseract  can
              better determine the text baseline position with a full line.

              For  -ocrd c, k2pdfopt detects each column of the converted file and passes that to
              Tesseract for conversion.

              For -ocrd p, k2pdfopt passes the entire output page of text to Tesseract  and  lets
              Tesseract  parse  it  for  word  positions.   Tesseract  has done considerable code
              development for detecting words on pages (more than k2pdfopt), so this should  also
              be a reliable way to create the OCR layer.

              One  drawback  to  -ocrd  c  or -ocr p is that there is no benefit to using the OCR
              multithreading option (see -nt).

              Require k2pdfopt built with leptonica.

       -ocrhmax <in>
              Set max height for an OCR'd word in inches.  Any graphic exceeding this height will
              not be processed with the OCR engine.  Default = 1.5.  See -ocr.

       -ocrlang <lang>|?
              Select  the  Tesseract  OCR Engine language.  This is the root name of the training
              data, e.g. -lang eng for English, -ocrlang fra for  French,  -ocrlang  chi_sim  for
              simplified  Chinese.   You can also use -l.  The default language is whatever is in
              your Tesseract trained data folder.  If you have more than one .traineddata file in
              that folder, the one with the most recent time stamp is used.

              NOTE 1: Use -ocrvis ? to see the list of Tesseract language files in your Tesseract
              data folder.

              NOTE 2: Using the -ocrvis t option will not show the OCR  text  correctly  for  any
              character  above  unicode value 255 since k2pdfopt does not use any embedded fonts,
              but the text will convert to the correct Unicode values when copy / pasted.

              NOTE 3: Tesseract allows the specification of  multiple  language  training  files,
              e.g.  -ocrlang  eng+fra  would  specify  English  as  the primary and French as the
              secondary OCR language.  In practice I have not found this to work very well.   Try
              multiple languages in different orders.

              Require k2pdfopt built with leptonica.

       -ocrdpi <dpi>

              Set  the  desired  dpi  of  the bitmaps passed to the OCR engine OR set the desired
              height of a lower case letter (e.g. 'e') in pixels.  If <dpi> is  positive,  it  is
              interpreted  as  dpi.  If <dpi> is negative, the absolute value is interpreted as a
              lowercase letter height in pixels.  Any bitmapped text sent to the OCR engine  will
              be  downsampled (if too large) so that the appropriate dpi or lowercase letter size
              is achieved.

              The default is 300 because I've found this works  best  empirically  for  Tesseract
              v4.0.0  English  OCR with font sizes in the range 8 - 15 pts.  Use a lower value if
              the font size in your document is larger than 15 - 20 pts.  Or use -ocrdpi  -24  if
              you have a wide range of font sizes.  Use -ocrdpi 0 to disable any downsampling.

       -ocrout[-] <namefmt>
              Write [don't write] UTF-8 OCR text output to file <namefmt>.  See the -o option for
              more about how <namefmt> works.  Default extension is .txt.  Default is no output.

       -ocrsort[-]
              When a PDF document has its own OCR/Text layer, this option  orders  the  OCR  text
              layer  by  its  position  on the page.  This should not be necessary unless the OCR
              layer was very poorly generated.  Default is -ocrsort- (off).

       -ocrsp[+|-]
              When generating the OCR layer, do an entire  row  of  text  at  once,  with  spaces
              between  each  words.   By default (-ocrsp-), each word is placed separately in the
              PDF document's OCR layer.  This causes problems with text selection in some readers
              (for example, individual words cannot be selected).  Using -ocrsp- may fix behavior
              like this, but will result in less accurate word placement since k2pdfopt does  not
              try to exactly match the font used by the document.  Use -ocrsp+ to allow more than
              one space between each word in the row of text in order to optimize  the  selection
              position.

       -ocrvis <s|t|b>
              Set  OCR  visibility  flags.   Put  's' to show the source doc, 't' to show the OCR
              text, and/or 'b' to put a box around each word.  Default is  -ocrvis  s.   To  show
              both  the source document and the OCR text overlayed on top:  -ocrvis st.  See also
              -ocr.  See also -ocrlang (the note about -ocrvis t).

       -odpi <dpi>
              Set pixels per inch of output screen (def=167). See also -dr, -w, -h, -fc.  You can
              also use -dpi for this.

              See also -fs, -mag.

       -om[b|l|r|t] <val>[<units>][,<val>[units][,...]]
              Set  the  blank  area  margins  on  the output device.  Works very much like the -m
              option.  See -m for more about the syntax.  Default = 0.02 inches.

              Note that the 's', 't', and 'x' units for -om all behave the same and scale to  the
              device  size.   E.g.  -om  0.1s  will  make the device screen margins 0.1 times the
              device width (for the left and right margins) or height (for  the  top  and  bottom
              margins) of the output device screen.

       -ow[-] [<mb>]
              Set  the  minimum  file  size  (in  MB) where overwriting the file will not be done
              without prompting.  Set to -1 (or just -ow with no value) to  overwrite  all  files
              with  no  prompting.   Set  to 0 (or just -ow-) to prompt for any overwritten file.
              Def = -ow 10 (any existing  file  over  10  MB  will  not  be  overwritten  without
              prompting).  See also -y option.

       -p <pagelist>
              Specify  pages  to  convert.   <pagelist>  must  not  have  any  spaces.   E.g.  -p
              1-3,5,9,10- would do pages 1 through 3, page 5, page 9, and pages  10  through  the
              end.  The letters 'e' and 'o' can be used to denote even and odd pages, e.g.

              -p o,e Process all odd pages, then all even ones.

              -p 2-52e,3-33o
                     Process 2,4,6,...,52,3,5,7,...,33.

              Overridden by -px option.  See -px.

       -pad <padlist>
              A shortcut for -pl, -pt, -pr, -pb.  E.g. -pad 15,10,13,20 is the same as -pl 15 -pt
              10 -pr 13 -pb 20.  Also, using -pad 15 will set all pads to 15, for example.

       -p[b|l|r|t] <nn>
              Pad [bottom|left|right|top] side of destination bitmap with <nn> rows.  Defaults  =
              4 (bottom), 0 (left), 3 (right), and 0 (top).  Example:  -pb 10.  This is typically
              only used on certain devices to get the page to come out just right.   For  setting
              margins on the output device, use -om. See also -pad.

       -png   (Default) Use PNG compression in PDF file.  See also -jpeg.

       -ppgs[-]
              Post  process [do not post process] with ghostscript.  This will take the final PDF
              output and process it using ghostscript's pdfwrite device (assuming ghostscript  is
              available).   A  benefit  to  doing this is that all "invisible" and/or overlapping
              text regions  (outside  cropping  areas)  get  completely  removed,  so  that  text
              selection capability is improved.  The actual ghostscript command used is:
              gs -dSAFER -dBATCH -q -dNOPAUSE -sDEVICE=pdfwrite
                 -dPDFSETTINGS=/prepress -sOutputFile=<outfile>
                 <srcfile>
              The default is not to post process with ghostscript.

       -px <pagelist>
              Exclude  pages from <pagelist>.  Overrides -p option.  Default is no excluded pages
              (-px -1).

       -r[-]  Right-to-left [left-to-right] page scans.  Default is left to right.

       -rls[+|-]
              Restore  [+]  or  don't  restore  [-]  the  last  command-line  settings  from  the
              environment  variable  K2PDFOPT_CUSTOM0.   The  default  (-rls)  is  to restore the
              settings if there are no other command-line options specified when  running  (from.
              either  the command line or the K2PDFOPT env var.), unless those options are "-gui"
              or specify a file name.

       -rsf <val>
              Row Split Figure of merit (expert  mode).   After  k2pdfopt  has  looked  for  gaps
              between  rows of text, it will check to see if there appear to be missed gaps (e.g.
              if one row is twice the height of all the others).  Increasing this value makes  it
              harder  for k2pdfopt to split a row.  Lowering it makes it easier.  Default value =
              20.

       -rt <deg>|auto[+]|aep
              Rotate source page counterclockwise by <deg> degrees.

              NOTE: If you're trying to get "landscape" output so that you can turn  your  reader
              on  its  side,  use  -ls instead of -rt.  The -rt option is intended to be used for
              when your source PDF is incorrectly rotated--e.g. if you view it on a  standard  PC
              reader and it comes up sideways.

              <deg>  can  be  90,  180, 270.  Or use "-rt auto" to examine up to 10 pages of each
              file to determine the orientation used on the entire file (this  is  the  default).
              Or  use "-rt aep" to auto-detect the rotation of every page.  If you have different
              pages that are rotated differently from each other within one  file,  you  can  use
              this  option  to  try  to  autorotate  each  source page.  Use -rt auto+ to turn on
              autodetect even in preview mode (otherwise it is off).

              See also -ls.

       -s[-]  Sharpen [don't sharpen] images.  Default is to sharpen.

       -sm[-] Show [don't show] marked source.  This is a debugging tool where k2pdfopt will mark
              the  source  file  with  the  regions  it  finds  on them and the order in which it
              processes them and save it as <srcfile>_marked.pdf.  Default is not to show  marked
              source.   Red  regions  are  found  on  the first pass (use -f2p -2 to put each red
              region on a separate page).  Green lines mark vertical regions affected by -vb  and
              -vs.   Gray  lines  mark individual rows of text (top, bottom, and baseline).  Blue
              boxes show individual words (passed to OCR if -ocr is specified).

       -sp[-] For each file on the command-line, just echo the number  of  pages--don't  process.
              Default = off (-sp-).

       -t[-]  Trim  [don't  trim]  the  white  space  from around the edges of any output region.
              Default is to trim.  Using -t- is  not  recommended  unless  you  want  to  exactly
              duplicate the source document.

       -title <title>
              Set the title metadata / property of the PDF output file(s).  Default is to use the
              title of the source document (-title "").  The <title> string will  be  parsed  for
              special  characters  that allow you to substitute the file name.  See the -o option
              for a description of these substitutions.

       -to[-] Text only output.  Remove figures from output.  Figures are determined  empirically
              as any contiguous region taller than 0.75 inches (or you can specify this using the
              -jf option).  Use -to- to turn off (default).

       -toc[-]
              Include [don't include] table of contents / outline / bookmark information  in  the
              PDF  output  if it is available in the source file (works only for PDF source files
              and only if MuPDF is compiled in).  By default, a new destination page  is  started
              at  each  bookmark  location.   Do  disable  this, see the -bp option.  If -toc- is
              specified, bookmark  information  from  the  source  file  is  ignored.   See  also
              -toclist.  Default is -toc.

       -toclist <pagelist>|<file>
              Override  the PDF source file's outline information (bookmarks / table of contents)
              with either a list of source pages or a file describing the table of  contents.  If
              you  specify  a  list  of  pages, e.g. -toclist 5,10,20,40,100 then those pages are
              marked as Chapter 1, 2, etc., respectively.  If you specify a file name,  the  file
              should be a text file formatted like this example:
                     1 Introduction
                     10 Chapter 1
                     +10 Chapter 1, Part A
                     +25 Chapter 1, Part B
                     ++25 Chapter 1, Part B, Subsection 1
                     ++27 Chapter 1, Part B, Subsection 2
                     +30 Chapter 1, Part C
                     50 Chapter 2
                     70 Chapter 3

              The  '+' indicates a sub-level heading (multiple +'s for multiple sub-levels).  The
              first number on the line is the source page reference number.  The rest of the text
              on the line is the name of the chapter / subheading.

              Note:   This  option  overrides -toc.  To get a template from an existing PDF file,
              see the -tocsave option.

       -tocsave <file>
              If an outline exists in the PDF file (and -toc is specified) write that outline  to
              text file <file> in the format required by -toclist.  See -toc, -toclist.

       -ui[-] User  input  query  turned  on  [off].   Default  = on for linux or if not run from
              command line in Windows.

       -v     Verbose output.

       -vb <thresh>
              Set gap-size vertical-break threshold between regions that cause them to be treated
              as  separate  regions.   E.g.  -vb  2 will break the document into separate regions
              anywhere there is a vertical gap that exceeds 2 times the median gap between  lines
              of text.  These separate regions may then be scaled and aligned independently.

              Special values:  Use -vb -1 to preserve all horizontal alignment and scaling across
              entire regions (vertical spacing may still be adjusted).  Use  -vb  -2  to  exactly
              preserve  each  region (both horizontal alignment and vertical spacing--this is the
              value used by -mode fw, for example).  The default is -vb 1.75.

       -vls <spacing>
              Set vertical line spacing as a fraction of the text size.   This  can  be  used  to
              override  the  line spacing in a document.  If 1, then single spacing is used.  2 =
              double spacing.  If negative, then the absolute value acts as  the  limiting  case.
              E.g.,  if  you set -vls -1.5, then any the line spacing of the original document is
              preserved unless it exceeds 1.5 (times single spacing).  Default = -1.2.  See  also
              -vs.

       -vs <maxgap>
              Preserve  up to <maxgap> inches of vertical spacing between regions in the document
              (marked in green when using -sm option).  This value has no effect  if  you  use  a
              negative value for -vb.  The default value is 0.25.

              See also -vls, -vb.

       -w <width>[in|cm|s|t|p]
              Set width of output device.  Default is 560.  See -h.

       -wrap[-|+]
              Enable  [disable]  text  wrapping.   Default = enabled.  If -wrap+, regions of text
              with lines shorter than the mobile device screen are re-flowed to  fit  the  screen
              width.  If you use -wrap+, you may want to also specify -fc- so that narrow columns
              of text are not magnified to fit your device.  Text wrapping  disables  native  PDF
              output (see -n option).  See also -ws, -j, -fc, -n.

       -ws <spacing>
              Set  minimum  word  spacing  for  line  breaking  as  a fraction of the height of a
              lowercase 'o'.  Use a larger value to make it harder to break lines.  If  negative,
              automatic  word  spacing is turned on.  The automatic spacing leans toward breaking
              long words between letters to be sure to fit text to the  device  display.   Def  =
              -0.20.   The  absolute  value  of  the  setting,  if negative, is used as a minimum
              allowed value.  If you want k2pdfopt to aggressively break lines (e.g. break  apart
              long  words  if  they  don't fit on a line), use a smaller absolute value, e.g. -ws
              -0.01.  A positive value works as it did in v2.18 and before.   The  default  value
              was changed from 0.375 in v2.18 to -0.20 in v2.20.  See also -wrap.

       -wt[+] <thresh>
              Any pixels whiter than <thresh> (0-255) are treated as "white".  Setting this lower
              can help k2pdfopt better process some poorly-quality scanned pages  or  pages  with
              watermarks.   Note  that  the  pixels  which are above <thresh> threshold value and
              therefore are treated as white are not actually changed to pure white (255)  unless
              the  '+'  is  also  included.   Otherwise, this only sets a threshold.  The default
              value for -wt is -1, which tells k2pdfopt to pick  the  optimum  value.   See  also
              -cmax, -colorfg, -colorbg.

       -x[-]  Exit [don't exit--wait for <Enter>] after completion.

       -y[-]  Assume  [don't  assume] "yes" to queries, such as whether to overwrite a file.  See
              also -ow.  Also turns off any warning messages.

SEE ALSO

       http://www.willus.com/k2pdfopt/

AUTHOR

       K2pdfopt is written by Willus.

       This manual page was written by Yangfl ⟨mmyangfl@gmail.com⟩ for the  Debian  Project  (but
       may be used by others).