Python: Image processing create wrinkled paper effect
Instead of using transparency, assuming you have two images of the same dimensions, one bright with the wrinkled paper and one with a dark text on a white background, you could try to take for every pixel the minimum of the values of the corresponding pixels in the two images.
In this way you should succeed in merging the text (darker than the wrinkled paper) and the wrinkled paper (darker than the original text background).
Maybe it is a little bit hard to describe my problem. I am searching for an algorithm in Python, to create wrinkled paper effect on a white image with some text. 
My first try was adding some real wrinkled paper image (with transparency) to the image with text. This looks nice, but hast the side effect, that the text is not really wrinkled.
So I am looking for a better solution, any ideas? Thanks