[SOLVED] Combining multiple masks/colors to generate image

[ivant]

Hi,

In a web-based app I'm developing, I need to recolor some images, using the customer specified colors. My take on this was, that the designers will create a series of masks and I'll paint them with the respective color and combine the results. The masks will be the same size, so I don't have to worry about how to combine them. I also wanted to do that without generating intermediate images on the disk, because I'll have to clean-up afterwards.

The problem is, that I can't understand how to combine the commands.

For single mask, I do this:

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convert -size {WxH} \
   \( xc:{color1} {mask1} +matte -compose Copy_Opacity -composite \) \
   {result}

For two masks, this:

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convert -size {WxH} \
   \( xc:{color1} {mask1} +matte -compose Copy_Opacity -composite \) \
   \( xc:{color2} {mask2} +matte -compose Copy_Opacity -composite \) \
   -compose Src_Over -composite \
   {result}

However, this doesn't work for three masks:

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convert -size {WxH} \
   \( xc:{color1} {mask1} +matte -compose Copy_Opacity -composite \) \
   \( xc:{color2} {mask2} +matte -compose Copy_Opacity -composite \) \
   \( xc:{color3} {mask3} +matte -compose Copy_Opacity -composite \) \
   -compose Src_Over -composite \
   {result}

Please, help me.

Cheers,
Ivan

P.S. The application is written in C++ and I'd rather have it call an external shell script to do the work, than to link it to IM.

[ivant]

While waiting for an an answer I decided to play a bit with the script using intermediate images. As I said I prefer not to, but it's better to have something working. So here is what I did:

• I prepared 3 image masks, each one containing an ellipse.
• Colored the masks in red, green and blue respectively, like this:

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  convert -size {size} xc:red mask1.png +matte -compose Copy_Opacity -composite r.png
  convert -size {size} xc:green mask2.png +matte -compose Copy_Opacity -composite g.png
  convert -size {size} xc:blue mask3.png +matte -compose Copy_Opacity -composite b.png

• Combined the results in one image:

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  convert r.png g.png b.png -composite res.png

The result was the same as with the single command line from the previous script! That is, red ellipse on top of green one, semi-transparent where they "collide". The blue ellipse is not present! Then I tried to combine just the red and the green:

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convert r.png g.png -composite rg.png

and it worked fine. But adding the blue one generated the same bad result:

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convert rg.png g.png -composite rgb.png

So, it looks like I understand IM even less than I thought (which wasn't much anyways).

Any ideas how to do that right?

P.S. Should I post the test images somewhere?

[Bonzo]

Is this the sort of thing you are trying to do?
http://www.imagemagick.org/Usage/compose/#bumpmap

Also a link to the images and an example of the final image you are looking to produce would help.

[ivant]

Is this the sort of thing you are trying to do?
http://www.imagemagick.org/Usage/compose/#bumpmap

Also a link to the images and an example of the final image you are looking to produce would help.

Actually, what I needed was like this: http://www.imagemagick.org/Usage/compose/#plus, but with "over" instead of "plus". And it worked fine! Thanks. And I've actually seen it before! I feel so stupid.

Also, looking at the top of the same page it's now clear that the command:

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convert 1.png 2.png 3.png -composite r.png

won't put 3 on top of 2 on top of 1 (as I was expecting), but will treat 3 as a mask and do something different with it. The correct command to do that is:

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convert \( 1.png 2.png -composite \) 3.png -composite r.png

Again, thank you very much!