Provided by: exactimage_0.7.4-2ubuntu1_i386 bug


       econvert - Image converter of the ExactImage library


       econvert  [--background]  [--bicubic-scale] [--bilinear-scale] [--blur]
       [--box-scale] [--brightness] [--colorspace]  [--compress]  [--contrast]
       [--convolve]   [--crop]  [--ddt-scale]  [--decompress]  [--deinterlace]
       [--deskew]  [--edge]  [--fast-auto-crop]  [--flip]  [--flop]  [--floyd-
       steinberg]   [--foreground]   [--gamma]   [--hue]   [-i|--input  INPUT]
       [--lightness]  [--line]  [--nearest-scale]   [--negate]   [--normalize]
       [-o|--output    OUTPUT]    [--quality]   [--resolution]   [--riemersma]
       [--rotate] [--saturation] [--scale] [--size] [--split] [--text]

       econvert --help


       ExactImage is a fast C++ image processing library. Unlike  ImageMagick,
       it  allows  operation  in several color spaces and bit depths natively,
       resulting in much lower memory  and  computational  requirements.  Some
       optimized  algorithms operate in 1/20 of the time ImageMagick requires,
       and displaying large images can be as fast as  1/10  of  the  time  the
       "display" program takes.

       econvert  is  a  command line frontend for the image processing library
       and mimicks Imagemagick’s convert. However since some  aspects  of  the
       convert   arguments  are  too  limited  (e.g.  even  now  we  have  two
       ditherizers to select from) or annoying (colorspace conversion is quite
       unintuitive  to control with Imagemagick and the data is often blown up
       to an more generic colorspace) the econvert syntax never  will  be  1:1
       compatible with convert. Also because those options only start with one
       dash (-) ... or are named density rather than resolution and so on.


           Background color used for operations.

           Scale image data with bi-cubic filter.

           Scale image data with bi-linear filter.

           Gaussian blur.

           (Down)scale image data with box filter.

           Change image brightness.

           Convert image colorspace (BW, BILEVEL, GRAY, GRAY1,  GRAY2,  GRAY4,
           RGB, YUV, CYMK).

           Compression  method  for  writing  images  (e.g.  G3, G4, Zip, ...)
           depending on the output format, a reasonable setting by default.

           Change image contrast.

           Convolution matrix.

           Crop an area out of an image: x,y,w,h.

           Scale image data with data dependant triangulation.

           Decompression method for reading images (e.g. thumb)  depending  on
           the input format, allowing to read partial data.

           Shuffleg every 2nd line.

           Deskew digitalized paper.

           Edge detect filter.

           Fast auto crop.

           Flip the image vertically.

           Flip the image horizontally.

           Floyd Steinberg dithering using n shades.

           Foreground color used for operations.

           Change image gamma.

           Change image hue.

       -i|--input INPUT
           Input  file or ’-’ for stdin, optionally prefixed with format: e.g:
           jpg:- or raw:rgb8-dump.

           Change image lightness.

           Draw a line: x1, y1, x2, y2.

           Scale image data to nearest neighbour.

           Negates the image.

           Transform the image to span the full color range.

       -o|--output OUTPUT
           Output file or ’-’ for stdout, optinally prefix with  format:  e.g.
           jpg:- or raw:rgb8-dump.

           Quality  setting  used  for writing compressed images integer range
           0-100, the default is 75.

           Set meta data resolution in dpi to x[xy] e.g. 200 or 200x400.

           Riemersma dithering using n shades.

           Rotation angle.

           Change image saturation.

           Scale image data using a method suitable for specified factor.

           Width and height of raw images whose dimensions are unknown.

           Filenames to save the images split in Y-direction into n parts.

           Draw text: x1, y1, height, text.

           Displays help text and exits.



       First image data must be read using -i or --input, processing  routines
       are  selected by their name with two leading dashes (e.g. --rotate) and
       at any point the data might be written into a file with -o or --output,
       for example:

       $ econvert  -i lenea.tiff --box-scale 0.5 -o medium.png --box-scale 0.5
       -o little.png

       Since version 0.3 the library tries to delay image decoding as much  as
       possible  and  provides  lossless and accelerated algorithms to work on
       compressed data (such as JPEGs) directly:

       $ econvert -i AV220-Scan.JPG --resolution 300x300 -o 1.jpg --rotate  90
       -o  2.jpg  --rotate  180 -o 3.jpg --rotate -90 -o 4.jpg --flip -o 5.jpg
       --flop -o 6.jpg --scale 0.25 -o thumb.jpg

       In this example 1.jpg will  be  created  from  the  original  JPEG  DCT
       coefficients,  those  coefficients will be rearranged and 2.jpg, 3.jpg,
       4.jpg, 5.jpg and 6.jpg will be written without any additional  loss  in
       precision  (no  new JPEG artefacts) and with outstanding speed. Only at
       the end, for image thumb.jpg, the DCT will actually be  decoded  -  but
       due  to the accelerated JPEG scaling only partially! The whole chain of
       operations applied to an 8 bit RGB JPEG only takes 0.99s on 2GHz  Intel

       Thumbnails of black and white (bi-level) images

       When  1  bit,  black and white, images are scaled down the output often
       might look pretty awful. The  box  scaling  algorithm  usually  does  a
       pretty  good  job  thumbnailing  b/w  images, however as the ExactImage
       algorithms always operate in the color-space the image data  is  stored
       in  the colorspace must be changed (e.g. to 8 bit gray) before applying
       the box scaler. At the end the result might be converted back to just a
       few shades of gray such as 2 or 4 bit:

       $ econvert  -i avision-bw-scan.pbm --colorspace gray8 --box-scale 0.125
       --colorspace gray2 -o thumb.png

       Slightly faster JPEG down-scaling

       As outlined in the lossless JPEG page, ExactImage  is  slightly  slower
       than  EPEG, though with noticeable higher output quality. If you do not
       care  about  quality,  only  about  bare  thruput  (maybe  in  an   web
       application?)  you can force nearest neighbor scaling by just specifing
       a scale factor the JPEG decoder can accellerate (1/2, 1/4, or 1/8)  and
       apply the remaining scalling manually. To archive a faster scaling with
       the effective factor 0.33:

       $ econvert -i big.jpg --scale .5 --nearest-scale 0.66 -o thumb.jpg

       Working with digital camera RAW data

       Digital still camera raw images differ from  model  to  model  and  are
       sometimes even obfuscated to prevent loading by third parties. However,
       ExactImage supports a wide range of RAW formats thanks to the  embedded
       dcraw  code  (we had to embed a copy of dcraw as the orignal project is
       only available as a command line program and not in form of a library -
       ExactImage  needs to have some more control about how the image data is
       passed around, e.g. in memory and not by pipes).

       Usually decoding of RAW  data  should  be  transparent  and  automatic,
       however  some  formats  also  are  valid  TIFF  files  and the embedded
       thumbnail might be picked by ExactImage’s TIFF support in favour of the
       actual  RAW  content.  This  this  cases  the dcraw backend decoder can
       explicitly be request with the decoder prefix of the input parameter:

       $ econvert -i dcraw:img_0123.cr2 ...

       As of version 0.6.5 ExactImage  also  allows  to  quickly  extract  the
       embedded  thumbnail  preview,  if  any,  by  specifing "thumb"(nail) as
       decompress argument before the image is loaded:

       $ econvert --decompress thumb -i dcraw:img_0123.cr2 ...

       This usually just takes parts of a second and  is  useful  to  generate
       previews, galleries, etc.

       Loading real raw data

       While  working  on  algorithms,  dumping  frame-buffer content or doing
       low-level driver development it often is handy to also  load  arbitrary
       RAW  pixel data. Via the "raw:" codec specification this is possible in
       econvert. As econvert does use the current color-depth (colorspace) and
       size  for  the  raw  data  they have to be specified before loading the
       image like this:

       $ econvert --size 1696x32 --colorspace rgb8 -i raw:data-file ...










       More information about econvert and the ExactImage project can be found
       at <>.


       ExactImage was written by ExactCODE GmbH <>.

       This manual page was written by Daniel Baumann <>, for
       the Debian project (but may be used by others).