Legacy ImageMagick Discussions Archive

Hi.
I'm not sure if it is a bug or Its me to try use incorrect that feature:

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -depth 8  txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (12336,12079,11565)  #302F2D  srgb(48,47,45)

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8  txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (12593,10537,10537)  #312929  srgb(49,41,41)

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8 -channel red -fx "r" txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (12593,10537,10537)  #312929  srgb(49,41,41)

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8 -channel red -fx "r<<1" txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,10537,10537)  #002929  srgb(0,41,41)

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8 -channel red -fx "r >> 1" txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,10537,10537)  #002929  srgb(0,41,41)

C:\devel\ImageMAgick>convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8 -channel red -fx "r>>1" txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (0,10537,10537)  #002929  srgb(0,41,41)

C:\devel\ImageMAgick>convert -version
Version: ImageMagick 7.0.3-9 Q16 x64 2016-12-05 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Visual C++: 180040629
Features: Cipher DPC HDRI
Delegates (built-in): bzlib cairo flif freetype jng jp2 jpeg lcms lqr openexr pangocairo png ps rsvg tiff webp xml zlib

C:\devel\ImageMAgick>ver

Microsoft Windows [Version 6.1.7601]

C:\devel\ImageMAgick>

Any attempt to use bitshift operator (<<, >> an dpossibly others) produces 0 or sometimes $ff

Best Regards
Willy.

I've found a workaround:

Code: Select all

$ convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8  txt:                    
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (12593,11565,10537)  #312D29  srgb(49,45,41)

$ convert rose: -crop 1x1+1+1 -ordered-dither threshold,32,64,32 -depth 8 -channel red -fx "((int(r*255)<<1)&254)/255" txt:
# ImageMagick pixel enumeration: 1,1,65535,srgb
0,0: (25186,11565,10537)  #622D29  srgb(98,45,41)

It seems that channel variables are real numbers not fx. byte as i can assume when i use -depth 8.
As I can remember it is not mentioned in the docs. So anyway, You can not use bitwise operators directly on channel data.

W.

Legacy ImageMagick Discussions Archive

Channel bitwise operations does not work.

Channel bitwise operations does not work.

Re: Channel bitwise operations does not work.