Ramble: Masking with Equalize — OZONE Asylum, home of the Mad Scientists

Ramble: Masking with Equalize

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Your Text: Insert Slimies » Insert UBB Code » Close Last Tag \| All Tags UBB Help	blah blah blah Many moons ago, I was into deconstructing HSL and simliar spaces. Hell, I was into deconstructing several colour spaces to sort out anomolies. Eventually it led to me to various techniques for extracting raw hue and saturation. Both of these channels were usually very blocky, which is consistant with compressing colour information more than lightness information. Once again, our eyeballs. I believe it was Deke that popularized an aspect of this. If you super saturate a photograph with even mild compression, what happens? The compression blocks become very apparent. I believe Deke's method uses Median and Gauss to fix. But what led me in a circle about Deke's method was his use of the Colour blending mode. Since I had become adept at extracting Colour = Hue + Sat, I knew exactly what was going on. He was using Median + Gauss to smooth colour information, and then putting it back in before uber saturating. Right? Right. Good and all, but I see several potential problems. The major problem being one of lines. As my old art teacher used to say, "There are no lines in real life - only changes." (Interestingly enough, that is why he didn't consider caricature a form of art.) While Median does (largely) respect lines, Gaussian Blur doesn't. Few other things that I don't like, but I'll keep them to myself. So we have all that blocky information that we want to be smooth. But we want to control the smoothness. You know, smooth in the flatter areas, but we don't want areas of contrast to bleed together. Quite often not necessarily true for colour work such as saturation, but we are looking to expand on an idea. Need a bit of room to flex and adapt. Smoothifying is a grand idea that is just begging to be expounded upon. Enter, of course, Lens Blur. With Lens Blur, we can put the lines wherever we want. We can make areas play nice and not play nice as we see fit. How do we go about making those lines? Of course you can draw them by hand as you see fit. Or maybe there is a more automated way. In an automated way of finding lines, there are more questions. Ugh! What data do we use and how do we manipulate it to get the lines we want? Now, there are two main branches of this technique that I use. I'm only going to talk about one of them. We are looking to generate a surface mask for use with Lens Blur. The mask in it's final form has to be greyscale. That right there answers the question of what data to use: Lum, of course. It just plain has the best resolution, so to speak. Use the better data to make the not so good data a little better. How do we manipulate Lum to get edges? For that, I'll point you to [url=http://tech-slop.serveit.org/wiki/index.php?title=Surface_Mask]Surface Mask[/url]. In a nutshell, use Sobel and LaPlacian to compliment each other. They do a very fine job when working together. Of course, I do have a beef with the LaPlacian method. That being that not all frequencies are equal across a photograph. On occassion, when I feel the need, I'll use Lens Blur to get variable High Pass, and then use that to get variable LaPlacian edges. Not often, but the human touch is required sometimes. What can you do with a surface mask? All sorts of things. For example, Equalize can seriously bring out compression badness, but a decently crafted surface mask can help ease the pain. Can also help with uber saturation (Deke). And a few other things, but I'll leave it to you to find them and explore. [small](Edited by [url=http://www.ozoneasylum.com/user/351]warjournal[/url] on 10-01-2006 11:05)[/small] Loading...
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