Legacy ImageMagick Discussions Archive

The guys at Mozilla noted that the max chunk size is configurable in libpng and fixed in it their code with a call to png_set_chunk_malloc_max(...):

https://hg.mozilla.org/integration/mozi ... 78699bdf7b

So, for all that it appears the generated PNG with 5 MB zTXt chunk is OK, no bug in that regard in ImageMagick. Except maybe the "truncated" warning. I guess there is no limit on the zTXt chunk size in RFC 2083? https://tools.ietf.org/html/rfc2083#page-27 https://tools.ietf.org/html/rfc20...

There's a 4'000'000 bytes limit in libpng on "not idat/fdat chunks" that Chrome currently avoids by patching libpng: https://bugzilla.mozilla.org/show_bug.cgi?id=1530222#c2 So, for all that it appears the generated PNG with 5 MB zTXt chunk is OK, no bug in that regard in ImageMagick. Remai...

I have been so free to create a bug report at mozilla, essentially asking for feedback or if there is an easy way to find out why Firefox considers the PNG not OK. (I also asked if this might be a security measure against attacks with images with very large non-image chunks): https://bugzilla.mozill...

Ghostscript 9.26: $ gs -version GPL Ghostscript 9.26 (2018-11-20) Copyright (C) 2018 Artifex Software, Inc. All rights reserved. magick moebius.pdf -density 300 -flatten -trim +repage -define png:exclude-chunk=zTXt PNG32:moebius.png => 5.3 MB, warning at identify afterwards, image has too low resolu...

This worked ( -define png:include-chunk=none ): convert -define png:include-chunk=none -density 300 -flatten -trim +repage moebius.pdf PNG32: moebius.png Lacks some metadata then like creation date tEXt chunk, but that is fine for my use case. I also tried just to exclude the zTXt chunk with -define...

I have run pngcheck (2.3.0, installed via macports): $ pngcheck -vt moebius.png File: moebius.png (7787908 bytes) chunk IHDR at offset 0x0000c, length 13 1012 x 13638 image, 32-bit RGB+alpha, non-interlaced chunk gAMA at offset 0x00025, length 4: 0.45455 chunk cHRM at offset 0x00035, length 32 White...

Correction: The large size of the PNG (moebius.png) and the warning are correlated, converting twice does not reduce the size of the other PNGs that I could convert from PDFs without warnings nor errors when opening then in Firefox. (I have not tried 100% all of them, but at least the ones most sim...

Overview I want to convert a PDF to a PNG while also trimming any white space and get a PNG that does not display everywhere (e.g. Firefox shows an error) and I also get a warning when I try to determine the image width with the "identify" command. Since this only happens with one of abou...