montage seems to be broken with -colorspace YCbCr

[abuisine]

Problem:
Image computed by montage is messy (chrominance)

Command line which cause the problem:

Code: Select all

montage -background black -tile 10x `for FRAME in 33 100 167 234 301 367 434 501 568 635 701 768 835 902 969 1035 1102 1169 1236 1303 1369 1436 1503 1570 1637 1703 1770 1837 1904 1971 2037 2104 2171 2238 2305 2371 2438 2505 2572 2639; do echo thumb_$FRAME.png; done` -geometry 160x90+0+0 -quality 100 -sampling-factor 4:2:0 -colorspace YCbCr pivot.jpg

OS:

Code: Select all

macOS Sierra 10.12.4 (16E195)

Version from homebrew:

Code: Select all

Version: ImageMagick 7.0.5-4 Q16 x86_64 2017-03-25 http://www.imagemagick.org
Copyright: © 1999-2017 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC HDRI Modules 
Delegates (built-in): bzlib freetype jng jpeg ltdl lzma png tiff xml zlib

How to mitigate:
output png from montage and then

Code: Select all

convert pivot.png -quality 100 -sampling-factor 4:2:0 -colorspace YCbCr pivot.jpg