artifacts on extracted alpha channel, dds format

[Tosyk]

Hello everyone.
My ver. of convert.exe is 6.7.9-4 Q16 and i'm on Window 7 x64

My command string is:

Code: Select all

convert Tex_0807_4.dds -channel rgba -separate +channel -swap 1,3 +delete -combine -channel B -evaluate set 100% +channel -colorspace sRGB Tex_0807_4_swap.png

When i'm trying to do operations (-separate, -combine etc) with alpha channel where the input format is .dds i gets artifacts every single time like on this picture (it's a copy of alpha channel from Alpha to Green):



BUT, if i'm useing other input formats like .tga or .bmp it's working fine and without any issue.

Here is experimental image

Topic where i get this issue is here

[anthony]

This is a repeat of my post from the original topic


It looks like cell bit order was reversed. Perhaps the alpha channel is not being decoded in-correctly for .dds files

Alpha is hard to see, and it may have slipped under the radar, by the developer of that codec.


But as it seems to be different for different machines. The next thing to try is turning off any multi-threading (on both computers). That can cause weird randomizations when something goes wrong.

If that fails, then it either delegate library, or some OS/Processor specific fault, though that last is unlikely.

[Tosyk]

Thye look like cell bit order was reversed. Perhaps the alpha channel is not being decoded in-correctly for .dds files
Alpha is hard to see, and it may have slipped under the radar, by the developer of that codec.

thank for looking into my issue

turning off any multi-threading

how to do that? it's a grapphic card or windows?

[fmw42]

I do not know if this works on Windows, but the easiest way for a simple command line test to turn off threading can be found at

viewtopic.php?f=2&t=20756&p=83407&hilit=thread#p83407