I have been able to do this in Photoshop Touch, by adding "fades". You can get more precise with Photoshop on your computer, but PS Touch may work for you.
Thanks for the input. Unfortunately there isn't any android app that is a true stitching program. Stitching isn't collage or panorama or using fading or blending. I've found one Windows program called i2k Quickage that stitches photo's. Unfortunately they don't have an app....
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