The image goes darker after mogrify

[yllan]

Dear,

I try to mogrify a image: http://cl.ly/image/152R243R1G1N
with the following commands: mogrify -flatten -scale x700 test.png

What I expect is: http://cl.ly/image/3p171l3l1F00
And the actual result is: http://cl.ly/image/0N1b143Z0Y1F

Version: ImageMagick 6.7.8-1 2012-07-06 Q16 http://www.imagemagick.org
OS: ArchLinux 3.4.4-3-ARCH #1 SMP PREEMPT Tue Jul 3 14:36:44 UTC 2012 x86_64 GNU/Linux

Any insight on how to get the thumbnail correct? Thanks!

[EDIT]
I use ImageMagick 6.7.7-6 2012-06-21 Q16 on Mac OS X 10.7.4 doesn't have this problem. It works as expected.

[glennrp]

Please try ImageMagick-6.7.8-3 or later. I verified that 6.7.8-0 and -2 produce
a darkened image while 6.7.8-3 and 6.7.8-6 produce the lighter image that
you expected. The problem was that your image was being converted to
the linear grayscale colorspace.

Also I noticed that the input image has an Apple "generic RGB" profile
which does not get written to the output file by IM-6.7.8-6, while
IM-6.7.8-0 writes a small corrupt iCCP chunk. This was a bug but
apparently not the cause of the colorspace change. IM-6.7.8-6
does not write an iCCP chunk but writes sRGB, cHRM, and gAMA
chunks instead. That's a mistake; the iCCP chunk should have
been copied from the input PNG to the output PNG.

[yllan]

I think there is a regression.

I am using 6.8.0-3 2012-10-27 Q16 (on 3.5.3-1-ARCH #1 SMP PREEMPT Sun Aug 26 09:14:51 CEST 2012 x86_64 GNU/Linux) .
The color profile is not correct.