Merge two opaque images to get a transparent one

Question

I need to extract an image from a PDF.

But since its background is transparent it's saved with a soft mask to create transparency.

While I'm able to extract the two opaque images below, I have no idea if there's a way to recreate the original image in Java. Could I use JAI?

Below there's the "main" image:

and here there's the corresponding soft mask:

I tried with ImageMagick with the command:

convert mask.jpg -background Black -alpha shape copy.png

and I almost got what I need but the foreground color is only black while the original one has also blue as foreground color.

Maybe show us how it is supposed to look when it is finished. — Mark Setchell, Feb 18 '15 at 09:06

score 3 · Answer 1 · answered Feb 18 '15 at 09:23

3

I think you probably want something like this, but it is hard to tell as you do not show us your expected result:

convert -fuzz 20% main.jpg -transparent black   \
     mask.jpg -compose copy-opacity -composite  \
     result.png

enter image description here

The -fuzz allows nearly black pixels in main.jpg to become transparent. The mask image is then loaded and its opacity copied to the main image.

answered Feb 18 '15 at 09:23

Mark Setchell

1

Wonderful! It's exactly what I need, but is there a Java equivalent? – alessmar Feb 18 '15 at 09:52
1

Sorry, I don't speak Java - I assumed you were happy with the command-line interface too, since you showed what you had been trying there. Maybe you could `shell exec` the ImageMagick command I gave, or have a look here http://stackoverflow.com/questions/19296075/how-would-i-use-the-imagemagick-library-with-processing – Mark Setchell Feb 18 '15 at 10:43

1 Answers1