with media-gfx/imagemagick 188.8.131.52-r1 ..
$ display -size 160x160 -depth 8 test.gray
Gives no error, but shows an image that is completely black. Converting the same image to tiff format with 'convert' works fine, and the picture is then viewable by 'display'. Curious.
I compiled imagemagick 6.2.6-0 from upstream, and the problem does not appear with that. For a test image I used some noise:
$ dd if=/dev/urandom of=test.gray bs=160 count=160
Could you try with imagemagick-184.108.40.206?
(In reply to comment #1)
> Could you try with imagemagick-220.127.116.11?
Yes, I just did.
It appears to fix the bug.
Fixed by upstream.