Legacy ImageMagick Discussions Archive

I did few tests with a raised-cosine filter :

http://i.imgur.com/UCppRpv.png

A0 = 1.0;
f0L = 0.02; f0H = 0.05;
A1 = 0.5;
f1L = 0.1; f1H = 0.2;
A2 = 1.0;
http://i.imgur.com/kzZxgSf.jpg

A0 = 1.0;
f0L = 0.00; f0H = 0.05;
A1 = 2.0;
f1L = 0.1; f1H = 1.0;
A2 = 0.1;
http://i.imgur.com/EqzcfYS.jpg ...

Here is my qtable generator:
/*
Written in 2014 by Jukka Ripatti
To the extent possible under law, the author have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.
See http ...

It seems to me that ITU-T.81 Annex K.1 is often misunderstood. Many software (including libjpeg) and hardware using the tables, despite the fact that the standart says "These tables are provided as examples only and are not necessarily suitable for any particular application."

xooyoozoo wrote:Edit: Well, I guess I missed the obvious fact that Photoshop automatically uses different quality factors for luma and chroma, and structural similarity completely focuses on luma.

Have you tried to convert images to monochrome before compression?

To that end, I whipped up a small comparison using a state-of-the-art perceptual metric, IW-SSIM What program you used for this comparison? This interest me, because it could help in the development of better quantization tables.

I tried previously to develop a SSIM optimized quantization table ...

Have you tried these in Windows with 32-bit binaries?

Tested on another PC (Windows 7) with http://www.imagemagick.org/download/bin ... indows.zip and the same error appears.
works without any errors.

rose: is too small for testing.

Sorry. I tested above commands again and corruption does not happened. Maybe this bug is difficult to repeat.

This is a easier repeatable example:

stream -map rgb -storage-type short images\logo.png - | echo abc

abc
stream.exe: IDAT: CRC error `images\logo.png' @ error/png.c ...

It seems that the stream does not properly handle situations where it can not write to a file.

stream -map rgb -storage-type char *.sgi - | x264 - -o testi.mkv --demuxer raw --input-csp rgb --input-res 1280x720 --fps 50 --quiet --frames 10

raw [info]: 1280x720p 0:0 @ 50/1 fps (cfr)
resize ...

stream images\logo.png - | dir > file.txt

stream: IDAT: CRC error `images\logo.png' @ error/png.c/MagickPNGErrorHandler/1282.
stream: Corrupt image `images\logo.png' @ error/png.c/ReadPNGImage/3252.
stream: missing an image filename `images\logo.png' @ error/stream.c/StreamImageCommand/762 ...

sphere.png:
http://img233.imageshack.us/img233/4008/sphereu.png

convert sphere.png -colors 50 spherecolors50.png
http://img691.imageshack.us/img691/610/spherecolors50.png

convert sphere.png PNG8:spherepng8.png
http://img833.imageshack.us/img833/6731/spherepng8.png

This works:
convert ...