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I would like to create an android app that would combine two photographs together to create something similar to what you would see in a double exposure photograph. Can you give me any ideas on how to do this?

yowza
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To get a true double-exposure, all you should need to do is add together the R/G/B values for each pixel with straight addition, with an upper limit of 255 for each component(for 24bpp at least). If it's too bright, you can always reduce it down some afterward.

Geobits
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  • Thanks so much for this answer. I am new to computer graphics. Can you point me to any books, tutorials, etc. that I could use to educate myslef to help me write some android photo apps. From reading the android graphics stuff on the google site I am finding I am missing some very basic concepts. – yowza Jun 05 '11 at 13:16
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    I haven't used the built-in Bitmap functions much, since my main project is mostly openGL primitives. From what I understand, the simplest way to do this is call getPixels() on your two Bitmap objects. This returns an array of color values for each pixel. Then you could add the color values in each, and call setPixels() into the 'new' Bitmap. The pixels are set up as ints, in ARGB order, so you might want to skip the alpha, though that shouldn't matter for photos specifically. This might nt be the fastest or most efficient way to do it, but it should work. – Geobits Jun 05 '11 at 15:22