Search found 9 matches

by nand
2015-03-16T02:50:45-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

Re: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

In that case, I'm getting different results: $ convert -version Version: ImageMagick 6.9.0-10 Q32 x86_64 2015-03-14 http://www.imagemagick.org Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC License: http://www.imagemagick.org/script/license.php Features: DPC HDRI Modules OpenCL Delegates ...
by nand
2015-03-15T16:14:36-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

Re: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

EDIT3: A Q32 build produces the correct result when the output is png64:file.png but an all-black
image when the output file is just q32.png
Do you mean Q64?
by nand
2015-03-14T14:27:51-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

Re: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

I can confirm that the official Gentoo package works fine when set to q32 instead of q64, as well.
by nand
2015-03-14T14:06:10-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

Re: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

Updates: It seems to be due to the configuration flags Gentoo was using. I've built directly from the source and it works. Then I built a second time with this configure line: ./configure --prefix=/usr --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --mandir=/usr/share/man --infodir=/usr/shar...
by nand
2015-03-14T13:44:22-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

Re: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

I've reproduced the bug on the current version of imagemagick, with the same results. $ convert --version Version: ImageMagick 6.9.0-10 Q64 x86_64 2015-03-14 http://www.imagemagick.org Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC License: http://www.imagemagick.org/script/license.php Fe...
by nand
2015-03-14T08:11:51-07:00
Forum: Bugs
Topic: ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff
Replies: 12
Views: 7730

ImageMagick can't open some PNG files, mostly 1-bit grayscale stuff

Example image: https://i.imgur.com/WyBCPty.png Trying to read/convert this with imagemagick fails, eg. $ wget https://i.imgur.com/WyBCPty.png ... $ convert WyBCPty.png test.ppm $ hexdump -C test.ppm 00000000 50 36 0a 38 37 20 38 37 0a 32 35 35 0a 00 00 00 |P6.87 87.255....| 00000010 00 00 00 00 00 0...
by nand
2015-02-24T16:20:57-07:00
Forum: Digital Image Processing
Topic: Scaling of EWA Lanczos function with non-standard window
Replies: 2
Views: 7543

Re: Scaling of EWA Lanczos function with non-standard window

How odd; I found that by blurring it *very* slightly (blur factor = 1.01), I got the hash pattern to go away entirely: radius≈3.238 blur=1.01: https://i.imgur.com/YzLMdfk.png ImageMagick seems to replicate this result. It gets even closer with blur=1.015, too. I wonder what the significance of this,...
by nand
2015-02-23T15:31:21-07:00
Forum: Digital Image Processing
Topic: Scaling of EWA Lanczos function with non-standard window
Replies: 2
Views: 7543

Re: Scaling of EWA Lanczos function with non-standard window

Update: I've modified my algorithm to support a fractional radius in an efficient way, so I can actually plug in the true radius of 3.2383154841662362 and see the results. Curiously enough, this still does not remove a hash pattern completely, even when using the “true” formula: jinc(x) * jinc(x * j...
by nand
2015-02-23T13:34:59-07:00
Forum: Digital Image Processing
Topic: Scaling of EWA Lanczos function with non-standard window
Replies: 2
Views: 7543

Scaling of EWA Lanczos function with non-standard window

EDIT: Never mind, I figured it out. Annotations in bold. Hey, I'm trying to implement EWA Lanczos rescaling in my application, and I'm trying to figure out what the best way to do this is. For starters, the underlying problem is that the true radius of the function (at 3 taps) is something like 3.2...