Converting/writing a BufferedImage to postscript

Question

I know how to draw some simple shapes using postcript

I'm now looking how to draw the content BufferedImage(width*height) to a postscript page (x,y,width,height) without any external library (FOP,PDFBox...).

Do you have any hint/code/algorithm ?

Thanks ! :-)

Answer 1

One has to use the image or colorimage operators. Unlike the simple linedrawing and showtext operator, these are complex operators that take several parameters.

I am putting a sample postscript snippet which renders an 8 x 8 image using the 7 parameter colorimage operator. Take notice that the 5th parameter is actually a callback procedure, that may be called several times by the colorimage operator, each time returning some of the image data in a string. In this example, I return the whole image data at once. In this example, this data is ASCII encoded with each byte being represented as 2-digit hexadecimal number. More efficient encodings are possible, as Postscript can decode base64, base85 and RLE encoding in runtime.

This parameter might be a single string instead of a callback procedure, but in this case, binary data would have to be escaped in octal, with a preceding slash (like \377) for decimal 255. Using inline data that is read with the currentfile operator is rather usual for representing Postscript images.

Note that the image is usually mapped to the (0,0,1,1) square on the renderign space, and one has to set the global transformation matrix (with the translate, scale, rotate operators) prior to rendering the image.

The complete image and colorimage reference can be found on the Postscript Language Refrence by Adobe available at http://www.adobe.com/products/postscript/pdfs/PLRM.pdf

For another example, try running the GIMP program and saving an image as Postscript from within it.

%!PS-Adobe-3.0

% builds string to hold all image data at once:
/imgdata 8 8 3 mul mul string def

% set context to scale image to 256 X 256 pt (from 1 x1 pt)

256 256 scale

% Dimensions of image (width * height * bpp)

8 8 8

% Image transformation Matrix - [width 0 0 -height 0 height]: flips 
% vertical axis so we have top to bottom data:
[8 0 0 -8 0 8] 

% Procedure to read the image data and return it as a string:
{ currentfile % read inline data
  imgdata  % put read data into this variable
  readhexstring % performs the reading
  pop % discards read operation status
}

%indicates single data source:
false

%number of colors per pixel:
3
% Image operator: consumes previous parameters and renders the image
% followed by Image hexadecimal data in ASCII
colorimage 
0000000000200000400000600000800000a00000c00000e0200000200020
2000402000602000802000a02000c02000e0400000400020400040400060
4000804000a04000c04000e06000006000206000406000606000806000a0
6000c06000e08000008000208000408000608000808000a08000c08000e0
a00000a00020a00040a00060a00080a000a0a000c0a000e0c00000c00020
c00040c00060c00080c000a0c000c0c000e0e00000e00020e00040e00060
e00080e000a0e000c0e000e0

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