NAME

       ppmtoyuv - convert a PPM image to an Abekas YUV file

SYNOPSIS

       ppmtoyuv [ppmfile]

DESCRIPTION

       This program is part of Netpbm(1).

       ppmtoyuv reads a PPM image as input and produces an Abekas YUV file as output.

       The  output  file  contains a raster of four byte YUV codes, each uniquely associated with
       two side-by-side pixels in the image.  The raster contains  rows  in  order  from  top  to
       bottom,  and within each row columns from left to right.  So the output file size in bytes
       is twice the number of pixels in the image.

       Each YUV code is associated with two pixels from the input image that  we  will  call  the
       left  pixel  and  the  right  pixel.   The 2nd byte of the code is the Y value of the left
       pixel.  The 4th byte of the code is the Y value of the right pixel.  The 1st byte  of  the
       code  is  an  average  of the U value of the pixel to the left of the left pixel, the left
       pixel, and the right pixel.  The 3rd byte of the code is analogous for  V  values.   These
       averages  are  weighted  arithmetic means where the left pixel is weighted double what the
       other two pixels are weighted.

       This format is reminiscent of but rather different from the common YUV 4:2:0  format  (aka
       YUV  420)  and the similar YUV 4:4:4, YUV 4:2:2, YUV 4:1:1, YUV 4:1:1s, and YUV 4:1:0.  In
       YUV 4:2:0, the raster is different for even numbered lines and  odd  numbered  lines.   On
       even  numbered  lines, there are twice as many bits for Y of each pixel as for U or V.  On
       odd numbered lines, there are the same number of bits for Y as on even numbered lines, but
       no bits at all for U and V.

       Another  YUV-based  format  is  YUV4MPEG2,  which  is  a  movie  format normally used with
       MJPEGTools ⟨http://mjpeg.sourceforge.net⟩ .  Netpbm does  not  have  converters  for  this
       format, but MJPEGTools does.

OPTIONS

       There are no command line options defined specifically for ppmtoyuv, but it recognizes the
       options common to all programs based on libnetpbm (See
        Common Options ⟨index.html#commonoptions⟩ .)

SEE ALSO

       yuvtoppm(1),        ppmtoeyuv(1),        ppmtoyuvsplit(1),        ppm(1),         pnmtoy4m
       ⟨http://mjpeg.sourceforge.net⟩ , y4mtopnm ⟨http://mjpeg.sourceforge.net⟩

AUTHOR

       Marc  Boucher  marc@PostImage.COM,  based  on  Example Conversion Program, A60/A64 Digital
       Video Interface Manual, page 69.

       Copyright (C) 1991 by DHD PostImage Inc.

       Copyright (C) 1987 by Abekas Video Systems Inc.

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master
       documentation is at

              http://netpbm.sourceforge.net/doc/ppmtoyuv.html