[RESOLVED]possible bug -opaque none IM 6.8.7.0 Q16 Mac OSX

[fmw42]

Neither of the following seem to turn transparency to black (or to any other color). It goes back at least as far as 6.8.6.9 which is currently the farthest back I can test.

convert logo: -transparent white -fill black -opaque none show:
convert logo: -transparent white -fill "rgba(0,0,0,1)" -opaque none show:

[snibgo]

As far as I know, "-fill black -opaque none" never turned transparent-black into opaque-black (or any other colour). This ...

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convert xc:None -fill Black -opaque none txt:

... returns transparent black for a large number of versions, back to v6.5.8.

EDIT: "-fill red -opaque None" seems to turn all fully-transparent pixels into transparent red. Eg:

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D:\web\im>"%IM%convert" xc:None xc:rgba(100%,100%,100%,0) -append -fill red -opaque none txt:
# ImageMagick pixel enumeration: 1,2,65535,srgba
0,0: (100%,0%,0%,0)  #FFFF000000000000  srgba(255,0,0,0)
0,1: (100%,0%,0%,0)  #FFFF000000000000  srgba(255,0,0,0)

[fmw42]

My workaround was to use

-background black -alpha background -alpha off

I am reasonably sure however that it used to work as I have scripts that use the concept to turn everything not trasparent to one color and then everything that is transparent to some other color.


I would have thought that if it was an issue with just black, then my work around is fine, but it fails for other colors (red here below).

The fails:
convert logo: -transparent white -fill red -opaque none show:

Snibgo, I just saw your edit above. So it looks like I just need to turn off alpha at the end.

This works:
convert logo: -transparent white -fill red -opaque none -alpha off show:


So this is a new behavior, though I do not know when it changed.

[fmw42]

Looking back at my old scripts, I see it needs -channel rgba to work the way I expected.

So this works
convert logo: -channel rgba -transparent white -fill red -opaque none show:

as does this:
convert logo: -channel rgba -transparent white -fill white +opaque none -fill black -opaque none show:

[snibgo]

"-channel rgba" changes the behaviour of fill: when it replaces a pixel, it will also replace the alpha value from the alpha value of the fill colour.

[fmw42]

You are probably right in that it was a -fill issue and not an opaque issue. So the title was also in error.

[snibgo]

Well, it depends on the operation that is using a fill colour. For example, with "label:", "-channel rgba" doesn't make a difference; the alpha from fill is always used.

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D:\web\im>%IM%convert -size 400x600 {-channel rgba} -background green -fill rgba(100%,0,0,0.25) label:snibgo s.png