Version 15 (modified by 16 years ago) (diff) | ,
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Placeholder for thoughts about Rubik’s Cube colourspace reduction for an art project.
Basics
I use a very simple palette: #fff #f00 #0f0 #00f #f80 #ff0
I have seen #FFFFFF, #000E98, #FF0000, #25C200, #F6FF00 #FF9C00 being used, too.
What’s difficult in this specific colour reduction exercise is that the convex hull of all available colours does not fill the entire RGB cube. The most important missing colour is black, but also cyan and magenta are missing. And yet we have orange, which is totally useless since we already have red and yellow: what did the Rubik’s Cube creators have in mind? Do they despise art so much?
Tests with existing software
Original image (left) and gamma-corrected image (linear intensity, will output correctly if a gamma = 2.2 correction is applied):
libpipi
Photoshop CS2
Results using Photoshop’s Floyd-Steinberg dithering:
Photoshop’s Floyd-Steinberg with 75% error distribution:
ImageMagick
This is ImageMagick’s Floyd-Steinberg algorithm. However, the results are so blurry that I suspect it to actually be their ridiculous Hilbert curve dithering implementation.
The Gimp
The Gimp fails pathetically. Results using its Floyd-Steinberg dithering algorithm:
Gimp’s Floyd-Steinberg with "reduced color bleeding" (probably a F-S variant that propagates less than 100% of the error):
Links
Attachments (18)
- lena.png (116.3 KB) - added by 17 years ago.
- lena-gimpfs.png (16.0 KB) - added by 17 years ago.
- lena-gimpfs2.png (11.9 KB) - added by 17 years ago.
- lena-gimpord.png (8.3 KB) - added by 17 years ago.
- rubik.png (261 bytes) - added by 17 years ago.
- lena-gimpgfs.png (14.8 KB) - added by 17 years ago.
- lena-gimpgfs2.png (11.7 KB) - added by 17 years ago.
- cube.png (53.6 KB) - added by 17 years ago.
- lena-im.png (32.0 KB) - added by 17 years ago.
- lena-gim.png (32.0 KB) - added by 17 years ago.
- lena-g.png (164.3 KB) - added by 17 years ago.
- lena-gimpgord.png (7.9 KB) - added by 17 years ago.
- lena-cs2fs.png (22.9 KB) - added by 17 years ago.
- lena-cs2fs2.png (23.6 KB) - added by 17 years ago.
- lena-gcs2fs2.png (21.2 KB) - added by 17 years ago.
- lena-gcs2fs.png (24.8 KB) - added by 17 years ago.
- lena-pipi.png (40.0 KB) - added by 16 years ago.
- lena-gpipi.png (76.0 KB) - added by 16 years ago.
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