Legacy ImageMagick Discussions Archive

What is the nature of your 50mb PNG files? Are they drawings, aero photos, maps, or what? Are they RGB, RGBA, indexed? All of these would be useful for figuring out how to proceed here. They are exported from Photoshop files (which are themselves large, from 1-2GB), created by artists drawing high-...

I'm looking at the libpng manual , and I'm wondering if that change will only work for interlaced images. With non-interlaced images, would ImageMagick be able to read in only a sample of the rows? I assume that this part about reading in one row at a time suggests it's possible: If you don't want t...

I've posted a feature request to the libpng mailing list, here: https://sourceforge.net/p/png-mng/mailman/png-mng-misc/thread/1159291813.1125196.1484857317904%40mail.yahoo.com/#msg35614399 glennrp , would you be interested in posting your patch to that thread, or should I? I'm hesitant to do it, bec...

I'm thumbnailing large (100MB-2GB) PSD files from within a Python application. Appending "[0]" to the input filename when using "convert" from the command line gives me a 4-6x speedup, with reduced disk and memory footprint. From what I've read, this is because it's only reading ...

Thanks. I'll check in with the libpng folks to see if it's something they're open to adding. What's the function in the JPEG library that's being used, if you happen to know? With JPEGs, it produces pretty good results if you follow the advice here: http://www.imagemagick.org/Usage/formats/#jpg_read...

I just discovered "-define jpeg:size={size}". It has led to a massive speedup in thumbnailing our very large (~50MB) JPEG files. Yay! In theory, the same thing should be possible with our very large PNG files, shouldn't it, since PNGs also support progressive loading? Is this already possi...