Trying to combine two images

Are there any good examples of using a mask to highlight portions of an image?  I have an onion-skin effect in mind, but could live with almost anything that is easy to see and does not obliterate the underlying image.  The goal is to paint a mask that will select irregular regions of an image.

If I have a black and white mask, I can use #eraseShape: and #reverse to get two separate images, and I appear to be able to make the masked portion of one of them transpaent and can (not terribly well) highlight the masked portion of the other.  Things quickly sprial down hill when I try to combine the two pieces.  Any pointers would be appreciatiated.

Bill


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Andreas,

The effect from your examples was very subtle on my display, but it looked promising so I started hacking it into my code.  The results were initially very strange, but I had been badly mangling the bitblt on my end.  Things went from weird to simply ugly and I started comparing the types of forms.  I was using ColorForm, so I switched that to Form (interestingly I had only recently started using ColorForm) and the results are now really nice.

I am curious what you meant about simplifying things if my mask were alpha.  AFAIK, I am perfectly willing to use it.  What would stop me?

Thanks!!

Bill



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