Search found 6 matches

by clawsoon
2017-01-23T11:05:11-07:00
Forum: Users
Topic: -define png:size={size}?
Replies: 11
Views: 10739

Re: -define png:size={size}?

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-...
by clawsoon
2017-01-20T08:19:04-07:00
Forum: Users
Topic: -define png:size={size}?
Replies: 11
Views: 10739

Re: -define png:size={size}?

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...
by clawsoon
2017-01-20T08:05:43-07:00
Forum: Users
Topic: -define png:size={size}?
Replies: 11
Views: 10739

Re: -define png:size={size}?

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...
by clawsoon
2017-01-19T13:36:55-07:00
Forum: Users
Topic: filename.psd[0] fast with convert but slow with PythonMagick
Replies: 0
Views: 8398

filename.psd[0] fast with convert but slow with PythonMagick

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 the first layer of t...
by clawsoon
2017-01-19T11:53:47-07:00
Forum: Users
Topic: -define png:size={size}?
Replies: 11
Views: 10739

Re: -define png:size={size}?

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...
by clawsoon
2017-01-12T10:45:14-07:00
Forum: Users
Topic: -define png:size={size}?
Replies: 11
Views: 10739

-define png:size={size}?

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 possible with I...