How come imagemagick output has nasty glitchy squares instead of smooth gradients?

Question

I'm trying to create filters like instagraph (https://github.com/webarto/instagraph), but the output images have nasty square-shaped transitions instead of smooth gradients. Why and how do I fix this?

The command I'm running is this: convert \( /home/trusktr/Pictures/hawaii_aug-2013/test/DSC05767.JPG -auto-gamma -modulate 120,50,100 \) \( -size 4240x2832 -fill rgba\(255,153,0,0.5\) -draw 'rectangle 0,0 4240,2832' \) -compose multiply /home/trusktr/Pictures/hawaii_aug-2013/test/DSC05767.JPG.kelvin.jpg

Here's the input image: http://ghz.me/oY

And here's the output (notice the sky isn't a gradient any more): http://ghz.me/oZ

Here's another example.

input image: http://ghz.me/p0

output image: http://ghz.me/p1

You can see in the arms some nast discolorization. Why? How do we defeat this evil magic?

score 0 · Answer 1 · answered Dec 01 '13 at 22:43

0

Your version of ImageMagick probably contains a bug. I just tried it with the latest version (6.8.7-8) and it created an image without the strange artifacts.

answered Dec 01 '13 at 22:43

dlemstra

7,813
2
27
43

How come imagemagick output has nasty glitchy squares instead of smooth gradients?

1 Answers1