Lab Sat - ChOps like this — OZONE Asylum, home of the Mad Scientists

Lab Sat - ChOps like this

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Your Text: Insert Slimies » Insert UBB Code » Close Last Tag \| All Tags UBB Help	Lab is a sphere, but Photoshop insists on using a cube. This means that saturation can't exactly be rho for whatever reasons and things. So, the sphere has to be cubed. Eh? What was that? No, we won't be using a straight-edge and a compass. Rather, let's take a trip with Mr. Peabody and visit with Kai the Krause of ChOps. Using the range -128 to 127, sat in lab as PS uses it: Sat = Max ( abs(a), abs(b) ) (Don't ask because I don't even want to begin to explain how I know that. Maybe later if you whisper nicely in my ear.) Since will be using ChOps in the Channels palette, the range in 0 to 255. This means offsetting by -128. We now have Sat = Max ( abs(a-128), abs(b-128) ) You know your ChOPs, right? Just by looking at that you know the ChOps needed, right? [i]Right?[/i] [i][b]Right?[/b][/i] - grab some photograph and go into Lab mode - copy it to a new layer Now, because of the 128 thing, we will need a channel with 128 to work with in a few of the steps. Since we want the colour information and Lab seperates colour and Lightness, might as well use L* channel. - channels palette > Lightness channel - Edit > Fill -- Use: 50% grey -- Mode: Normal Now, going to use that L @ 50% for the abs() part. - channels > a channel - Image > Apply Image -- Channel: Lightness -- Blending: Difference Cool beans. Now to abs() the b channel. - channels > b channel - Image > Apply Image -- Channel: Lightness -- Blending: Difference Cool beans x2. Now, how do we get the Max of those those two? Lighten! - channels > a channel - Image > Apply Image -- Channel: b -- Blending: Lighten Uber cool beans. Now all we have to do is clean it up so that it's all in one channel for easy tweaking. - channels > b channel - Edit > Fill -- Use: 50% Grey -- Mode: Normal Uber cool beans x2. Go back to Layers and set to Saturation. Turn it on/off and be amazed at the differences that you don't see. Oh... Ah... To tweak, of course, you tweak the a channel. And, because of the 128 thing, you only tweak half. Yeah, kind of sucks that sat in Lab is limited to such a small range, but still a good technique for global saturation. Even if you think it sucks as a technique, it is still fun and a good exercise. Still shaking pillars. play.fiddle.learn [small](Edited by [url=http://www.ozoneasylum.com/user/351]warjournal[/url] on 03-14-2006 20:14)[/small] Loading...
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