Manual: ppmtoyuv

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 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 .	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 pro‐
       grams based on libnetpbm (See  Common Options .)

SEE ALSO
       yuvtoppm(1), ppmtoeyuv(1), ppmtoyuvsplit(1), ppm(1), pnmtoy4m , y4mtopnm

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)