Runlength-encoded Gray or Color Images

[cristy]

For your toolbox. This procedure displays a grayscale or color
runlength-encoded image as specified by the grayscale parameter. This is my
first postscript program so be gentle. Note that all user definable
parameters is read as data at the end of the postscript program.

%!
%
% Display a runlength-encoded image.
%
/buffer 512 string def
/byte 1 string def
/color_packet 3 string def
/gray_packet 1 string def
/expanded_packet 768 string def

/ReadColorPacket
{
%
% read one runlength-encoded color packet (length red green blue).
%
currentfile byte readhexstring pop 0 get
/count exch 1 add def
/count count 3 mul def
currentfile color_packet readhexstring pop
0 3 count 1 sub
{
expanded_packet exch color_packet putinterval
} for pop
expanded_packet 0 count getinterval
} def

/DisplayColorImage
{
columns rows 8
[
columns 0 0
rows neg 0 rows
]
{ ReadColorPacket } false 3 colorimage
} def

/ReadGrayPacket
{
%
% read one runlength-encoded grayscale packet (length gray).
%
currentfile byte readhexstring pop 0 get
/count exch 1 add def
currentfile gray_packet readhexstring pop
0 1 count 1 sub
{
expanded_packet exch gray_packet putinterval
} for pop
expanded_packet 0 count getinterval
} def

/DisplayGrayImage
{
columns rows 8
[
columns 0 0
rows neg 0 rows
]
{ ReadGrayPacket } image
} def

/DisplayImage
{
%
% display runlength-encoded image.
%
initgraphics
gsave
currentfile buffer readline pop
token { /degrees exch def } { } ifelse
degrees rotate
currentfile buffer readline pop
token { /x exch def } { } ifelse
token { /y exch def } { } ifelse
x y translate
currentfile buffer readline pop
token { /x exch def } { } ifelse
token { /y exch def } { } ifelse
x y scale
currentfile buffer readline pop
currentfile buffer readline pop
token { /columns exch def } { } ifelse
token { /rows exch def } { } ifelse
currentfile buffer readline pop
token { /grayscale exch def } { } ifelse
grayscale 0 gt { DisplayGrayImage } { DisplayColorImage } ifelse
} def

%
% DisplayImage parameters:
% degrees rotation.
% x & y translation.
% x & y scale.
% image name.
% image columns & rows.
% grayscale.
% hex runlength encoded packets.
%
DisplayImage
0.000000
274.000000 364.000000
64.000000 64.000000
image name
64 64
0
3daaaacd00a3a3c5009796b83daaaacd00a6a5c8008c8db43daaaacd00a6a5c8009999bc
< lots more data >
0015394a0713384a0413394c0015394a00323e4c
grestore
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