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Re-validating KPT #13



It took me awhile to figure out, but I did manage to get it. I would have had it sooner if I had trusted my gut more and had more time to play with such things.

Posted at GN and I thought you folks might like a gander. With some editing and more graphics, this will eventually be added to Tech-Slop. Consider this a first rough draft. If I really dig into it, I might even have some more surprises to do with this technique.

So... what's the problem? One of the original KPTs has been totally rendered obsolete. Specifically KPT #13. What? Well, PS no longer supports HLS or HSB modes. Pretty nifty things can be done. Too bad it's gone. Talk about suck.

HLS = Hue Luminosity/Lightness Saturation
HSB/V = Hue Saturation Brightness/Value

HSB and HSV colour models are the same. There is technical difference between HSB and HLS, but most people use them interchangably. Bascially breaks down to context, but it is good to know that there is a difference. For the truly curious, hit Google.

Okay, so let's look at Biker Chic in RGB mode:
She's my hero.

There is a plugin that can pseudo-convert between the modes. "Digital Imaging Tools" or something. I believe it comes with PS in the Goodies or Extra folder or nearest equivalent. You can download it off the web. Check your local listings.

By pseudo-convert, I mean that it changes the channels, but not the mode. To see what I mean, let's take a peek at Biker Chic in HLS colour space, but rendered in RGB:

If you look at the RBG channels, you'll see that they are way different. The Red channel is now Hue; the Green channel is now Luminosity; and Blue is now Saturation. However, they are still rendered in RGB by PS. More suck.

In order to re-validate Kai's work, we have to know how to convert back to RGB once the channels are mangled. The plan of attack is to take the HLS (RGB) channels from the mangled picture, then reconstruct them in a new document in the Layers palette. Sounds kind of weird taking channels and putting them back together again in the Layers palette, eh?

Let's get to work reconstructing. Sounds good to me.

This is pretty much what the layers of the reconstructed document looks like:

At the very bottom, we have "hue base". This is the Hue/Red channel pasted in a new doc. Directly above it, there is a Gradient Map. The Grad-Map uses the "full spectrum" setting and it's Reversed to read ROYGBPR. That takes care of the Hue.

The next layer up in the Green/Lum channel pasted in. Blending mode is set to Luminosity. Makes sense to me.

Above that is the Blue/Sat channel pasted in. Blending mode is set to Saturation. Above that is a clipped Grad-Map. Now, this is a bit tricky. The left side of the Grad-Map is pure black. That is, a Saturation value of 0. At the other end of the Grad-Map, is a random colour with a Saturation value of 255. The Brightness value of the Sat: 255 does make a difference. However, the Brightness value of the Sat: 0 does not make a difference.

Did you catch that?

Notice that I reconstructed an HLS picture. It's not a perfect reconstruction as there are some differences when compared to the original, but it's a lot closer than trying to reconstruct an HSB picture. Although for fiddling for funky things, being pixel perfect isn't exactly required.

There is a way to deal with the Sat using one layer, but it's backwards. I'll deal with this little nugget later.

When I get some serious time, I'll go into more graphic detail with some Tech-Slop. You know, screen-caps of the Grad-Maps and all that. I might even record and Action to set things up for serious fiddling. Hopefully this weekend.

Speaking of fiddling, it's a lot of fun to get crazy once the layers are set up. Grab the gradient tool with various modes and get crazy with the Cheeze Whiz.


Thanks for this. I logically deduced (me be genius heheee) that there should be more KK tips and tricks over there and I found them.
Must say that I've always been very fond of KPT5 from the first time I saw the box, but it was rather expensive... But then KPT 6 was released, and in the early summer discount weeks (a tradition here in Absurdia), I saw... KPT5 box at half price. They must've been convinced that 6 was an upgrade. So I bought it, and found on the CD as a bonus KPT3 which are even more my liking despite their small interface (Terrazzo from Xaostools suffers from the same limitation).
To use KPT3 in PS7 is rather complex when saving (see Adobe forums for a solution), but there are other pixel based apps than PS! And Adobe is not going to dictathe the law of what can be used and what can't.

Yet, I haven't installed them (yet?) as PS itself offers so many possibilities...


Thanks for your contribution Stroker, very interesting :perfect: As soon as I can find some time, I have to play with it myself too.


Eric, this is about Kai's Power Tips -- not Kai's Power Tools (which are plug-ins). I am a bit baffled as to why this was moved to the filter section. But it doesn't really matter, I guess.

More specifically, this is about taking one of Kai's old works, and bringing it up to speed since HSB/HLS is out of PS. KPT #13 can not be done with modern versions of PS the way he presents it. I am providing a work-around.

I really hate it when people let silly little things inhibit their journey. Hopefully I can put some of the "play.fiddle.learn" back into Kai's out-dated work.


Finally did the write up.
KPT #13 Revisited

This is probably going to be my last Tech-Slop piece for some time. After this weekend, I'm a full-time dad for two daughters and that will seriously cut into my play time.

edit: Man, writing a vacuum does wonders. I've already spotted two glaring errors.