imaging_util

Imaging lingo utility From: "James Newton" <jnewton@cqm.co.uk> To: <lingo-l@penworks.com> Subject: Re: <lingo-l> Imaging lingo utility > I've written a utility that will import the screen grabs, compare > them against a key image, and crop each so that only the changed > pixels remain. Now I'm looking to optimize it. Hi Kurt, Thanks to Macromedia's Werner Sharp, here is a handler that will calculate the difference between two images. It takes roughly 750 ms to treat an 800x600 pixel image on a Pentium II at 400 MHz. Hats off to Werner! James ---------------------------------------------------------------------- on isolateDifferences(image1, image2) -------------------------------- -- Returns an image which represents the differences between -- <image1> and <image2>. -- -- PARAMETERS: <image1> and <image2> are expected to be images of -- identical size, shape and color depth -- -- This handler was generously sponsored by Werner Sharp. -------------------------------------------------------------------- -- Determine dimensions imageRect = image1.rect -- 1. create copy of image1 delta = image1.duplicate() -- 2. isolate different pixels as non-white delta.copyPixels(image2, imageRect, imageRect, [#ink: #reverse]) -- 3. create 1-bit mask image and fill with solid black theMask = image(imageRect.width, imageRect.height, 1) theMask.fill(imageRect, rgb(0, 0, 0)) -- 4. copy only non-white pixels over to destination but at the -- same time make them white so we're left with only white and -- black pixels. The white ones are the different pixels, the -- black pixels are the same. options = [ \ #ink: #backgroundTransparent, \ #color: rgb(255, 255, 255), \ #bgcolor: rgb(255, 255, 255) \ ] theMask.copypixels(delta, imageRect, imageRect, options) -- 5. invert the 1-bit mask theMask.copypixels(theMask, imageRect, imageRect, [#ink: #notCopy]) -- 6. use theMask to copy only the different pixels over from image2 delta.fill(imageRect, rgb(255, 255, 255)) -- recyle delta delta.copyPixels(image2, imageRect, imageRect, [#maskImage:theMask]) return delta end isolateDifferences