-channel

[GreenKoopa]

-channel applies to -fx, but not -poly or -average. Is there reason?

Code: Select all

convert -size 500x500 xc:#F00 xc:#0FF -channel B -average ave.png
convert -size 500x500 xc:#F00 xc:#0FF -channel B -poly "0.5,1 0.5,1" poly.png
convert -size 500x500 xc:#F00 xc:#0FF -channel B -fx "(u+v)/2" fx.png

[fmw42]

use -channel b -separate for those other cases

[GreenKoopa]

Sure, I could do this:

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convert -size 500x500 xc:#F00 xc:#0FF   ( -clone 0-1 -average ) -delete 1 -compose Copy_Blue -composite x.png

So -fx and -level supporting -channel is unnecessary. But it sure is convenient, so why the difference?

[fmw42]

As far a I know only some functions support the channel flag. Most were retrofit at needed. I don't think the channel flag was a part of IM 6 originally except in connection with -separate.

But the IM developers can explain further or correct me if needed.

[magick]

Many of the image filters support -channel in ImageMagick version 6. Channels are fully integrated into version 7, meaning any image filter, where it makes sense, supports a channel mask.

[GreenKoopa]

Thank you for the past history and future roadmap. All of your efforts are much appreciated!