Ppmtoyuv User Manual(1) General Commands Manual Ppmtoyuv User Manual(1)
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 con-
tains 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 num-
bered lines, but no bits at all for U and V.
Another YUV-based format is YUV4MPEG2, which is a movie format normally
used with ]8;;http://mjpeg.sourceforge.net\MJPEGTools]8;;\ . 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
]8;;index.html#commonoptions\ Common Options]8;;\ .)
SEE ALSO
yuvtoppm(1), ppmtoeyuv(1), ppmtoyuvsplit(1), ppm(1), ]8;;http://mjpeg.sourceforge.net\pnmtoy4m]8;;\ , ]8;;http://mjpeg.sourceforge.net\y4mtopnm]8;;\
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
netpbm documentation 06 June 2005 Ppmtoyuv User Manual(1)
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