Imagemagick: generate raw image data for embedding PDF fleets?

Question

I am trying to find a command line example, a PDF source code example (see also How to create plain text PDF examples that work in viewing a document? ), But with an image attachment. This is how far I got - I have a hello.pdf template:

 %PDF-1.4 1 0 obj << /Type /Catalog /Outlines 2 0 R /Pages 3 0 R >> endobj 2 0 obj << /Type /Outlines /Count 0 >> endobj 3 0 obj << /Type /Pages /Kids [ 4 0 R ] /Count 1 >> endobj 4 0 obj << /Type /Page /Parent 3 0 R /MediaBox [ 0 0 612 792 ] /Contents 5 0 R /Resources << /ProcSet 6 0 R /Font << /F1 7 0 R >> /ProcSet [ /PDF /Text /ImageC ] /XObject << /Im1 8 0 R >> >> >> endobj 5 0 obj << /Length 173 >> stream BT /F1 24 Tf 100 100 Td ( Hello World ) Tj 200 200 Td ( Hello Again ) Tj % width skew-right-up skew-top-right height xy 150 0 0 150 340 130 cm % 150 150 Td - irrelevant for image /Im1 Do ET endstream endobj 6 0 obj [ /PDF /Text ] endobj 7 0 obj << /Type /Font /Subtype /Type1 /Name /F1 /BaseFont /Helvetica /Encoding /MacRomanEncoding >> endobj 8 0 obj << /BitsPerComponent 8 /ColorSpace /DeviceRGB /DecodeParms << /BitsPerComponent 8 /Colors 3 /Columns 150 /Predictor 10 >> /Filter [ /FlateDecode ] /Height 150 /Length 1418 /Subtype /Image /Type /XObject /Width 150 >> stream ###endstream endobj 9 0 obj [ /PDF ] endobj xref 0 10 0000000000 65535 f 0000000009 00000 n 0000000074 00000 n 0000000120 00000 n 0000000179 00000 n 0000000364 00000 n 0000000466 00000 n 0000000496 00000 n 0000001000 00000 n 0000001100 00000 n trailer << /Size 10 /Root 1 0 R >> startxref 625 %%EOF 

Then I generate the image data using convert , and apply the flate compression with zlib :

 convert -size 150x150 gradient:\#4b4-\#bfb test.ppm du -b test.ppm # 135017 bytes python -c "import zlib,sys;sys.stdout.write(zlib.compress(sys.stdin.read()))" < test.ppm > test.flate du -b test.flate # 1418 bytes 

Then I replace /Length 1418 in the file and finally replace the ### token using:

 perl -ne 's/^###/`cat test.flate`/e;print' hello.pdf > hello2.pdf 

This file obviously has the wrong xref table, but opening in evince just fine:

... however, it is obvious that the bitmap is not in the correct format.

I also tried to generate, say,

 convert -size 150x150 gradient:\#4b4-\#bfb -endian LSB rgb:test.raw 

... but they are not green at all (as the original image should be).

Does anyone know the correct image format - and the convert command line - to create a raw image that you can "go down" and include in pdf?

Thanks a lot in advance for any answers,
Hurrah!

Answer 1

Ok, fixed it; the problem was that you need to specify an 8-bit depth on the convert command line; thus the correct call:

 convert -depth 8 -size 150x150 gradient:\#4b4-\#bfb rgb:test.raw 

Then we have:

 du -b test.raw # 67500 bytes python -c "import zlib,sys;sys.stdout.write(zlib.compress(sys.stdin.read()))" < test.raw > test.flate du -b test.flate # 664 bytes # replace /Length 664, and then: perl -ne 's/^###/`cat test.flate`/e;print' hello.pdf > hello2.pdf 

Finally, hello2.pdf opens in evince and displays the bitmap correctly:

Btw, I found this because I'm actually trying to debug an image in another document; so I basically did the following:

 # extract and save the stream of this image object qpdf --show-object=23 --raw-stream-data mybadfile.pdf > myraw.file # get raw binary data - deflate the saved object stream python -c "import zlib,sys;sys.stdout.write(zlib.decompress(sys.stdin.read()))" < myraw.file > myraw.deflate identify myraw.deflate # identify: no decode delegate for this image format `myraw.deflate' @ constitute.c/ReadImage/530. identify rgb:myraw.deflate # identify: Must specify image size `myraw.deflate' @ rgb.c/ReadRGBImage/155. identify -size 588x508 rgb:myraw.deflate # rgb:myraw.deflate=>myraw.deflate RGB 588x508 588x508+0+0 16-bit TrueColor DirectClass 875KiB 0.020u 0:00.030 # identify: Unexpected end-of-file `myraw.deflate': No such file or directory @ rgb.c/ReadRGBImage/261. display -size 588x508 rgb:myraw.deflate # display: Unexpected end-of-file `myraw.deflate': No such file or directory @ rgb.c/ReadRGBImage/261. ### but it shows correctly, except for size? identify -depth 8 -size 588x508 rgb:myraw.deflate # rgb:myraw.deflate=>myraw.deflate RGB 588x508 588x508+0+0 8-bit TrueColor DirectClass 875KiB 0.020u 0:00 ## OK display -depth 8 -size 588x508 rgb:myraw.deflate # OK; choosing rgba: is already bad - so confirmed 8-bit rgb 

Hope this helps someone
Hurrah!