Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
Recent versions of ImageMagick account for the alpha channel when trimming. Perhaps you are using an older version of ImageMagick or perhaps you need to increase the fuzziness (e.g. -fuzz 40%).
Chances are your image does not have a uniform background color which stops the trimming from working as you had hoped. You might be able to eliminate some noise with a median filter first and see if that makes a difference.
ggambett wrote:
The alpha channel is correctly empty in the left zone. The color channels do have color data in some of the transparent areas, as shown with -separate.
There are a few pixels in column 0 whose alpha value differs, as you can see with:
