IM 6.7.8.10beta Q16 Mac OSX SnowLeopard
I am finding that saving an output, the results look different if one adds -write xxx before the output image.
It depends upon the format of the xxx image, but especially with gif. This is happening when using -selective blur with or without -mask.
The results appear to be affected by the gif quantization even in the actual output.
Is this a bug or correct behavior?
Look carefully at the top of the image in the gray area to the left of her hair.
Input:
No Write added -- correct result:
imb convert 1tmp12.png -selective-blur 0x2+10% +mask 1tmp21_no_write.png
You may need to flicker the results to see the differences.
Write to gif added -- corrupted, noisy result:
imb convert 1tmp12.png -selective-blur 0x2+10% +mask -write 1tmp_sb.gif 1tmp21_gif_write.png
If I use -mask, it is even worse.
Mask (binary):
No Write added -- correct result:
imb convert 1tmp12.png -mask 1tmp3.png -selective-blur 0x2+10% +mask 1tmp20_no_write.png
Write to gif added -- corrupted, noisy result:
imb convert 1tmp12.png -mask 1tmp3.png -selective-blur 0x2+10% +mask -write 1tmp_sb.gif 1tmp20_gif_write.png
possible bug on save when using -write IM 6.7.8.10beta
Re: possible bug on save when using -write IM 6.7.8.10beta
Some image formats have particular requirements and the image is modified accordingly before it is written. GIF, for example, requires an image colormap. If the image does not have a colormap, one is created before it is written in the GIF format. This change persists after the image is written. If you want to eliminate side-effects, use the +write option.