Technical Slop

KPT #13 Revisited

It all starts right here: KPT #13: Colonization II: and Hue and Eye (See also: Kai's Power Tips).

As Kai says in the very beginning, it's obsolete because PhotoShop no longer supports HSB and HSL modes. Suck! So, let's do a little CPR on it and see if we can breath some new life into it.

But first, we have to get a few things out of the way. There are two basic colour models and there is a lot of intermingling between them. For the most part, a lot these things are interchangeable, but there are some differences when you get into the nitty gritty.

H = Hue
S = Saturation
B = Brightness
V = Value
L = Lightness, Lumen, Luminescence

That means that:
HSB = Hue, Saturation, Brightness

Value is basically the same as Lightness and it's kin. So, HSV, HSB, and HSL are all the same thing... sort of.

HSB and HSV are one colour model. HSL, sometimes HLS, is another colour model. They are very similar, but there are some very technical differences. Generally, people that don't know of the difference use them to mean the same thing, so it usually boils down to context.

In the all of the research I've done concerning HSB and HLS, the above about mixing terms is spot on.

In what we are about to do, I suspect that it's more of an HLS model instead of HSB. I still have yet to sort this out to my satisfaction. Believe me, it gets confusing sometimes.

Let's start reconstructing, shall we?

Here we are with a new document. So far 3 Layers have been added.

At the very bottom we have Background. This is to act as our base for Hue. I laid a really simple gradient to it just for kicks.

Above that is a Adjustment Layer > Gradient Map. The Grad-Map using the "Spectrum" gradient from the default gradient library.

The "Spectrum" gradient in the Ad-Layer Grad-Map looks something like this.

In this graphic, the gradient is actually backwards. In order for it to be correct, click the Reverse button.

And then, above that, is another Layer set to Luminosity. This acts as our Brightness in HSB. Again, I tossed a simple gradient in there.

This is what it looks like so far.

I really should have checked the Reverse button. So much for that now.

Pretty easy so far, but things are about to get a little hairy. Not much - just a little.

Now, doing the Saturation in HSB is a little tricky. I had some problems with this for quite some time. Then I got to looking at the formulas and it made sense.

Here are the formulas for Value and Saturation. Bugger! Not math! Yeap, rather profound math for our edification.

What does it mean? Why does it affect us? What gives, man?

If you stare at it long enough, you'll realize that S is very dependent on V and Min(RGB). If you stare at it even longer, you will realize that black, white, and shades of gray have Sat: 0. If you stare at it yet longer, you'll realize that Max(RGB) - Min(RGB) = 255 will give Sat: 255.

Oh, bugger!

What? Still don't get it? Okay, let's move on and clear this up.

Okay, time for two more Layers.

The next one is set to Saturation. Again, another quick gradient tossed in.

Now clip a Gradient Map Adjustment Layer to it. Let's take a closer at this Grad-Map Ad-Layer.

This is where that lovely math comes into play.

Colour #1 can be black, white, or any shade of gray that you choose.

Colour #2 can be almost any colour that you choose. You just have to make sure that at least one RGB value is 0 and that another RGB has a value of 255. You can mess around all you want with colour #2 as long as Max(RGB) - Min(RGB) = 255.

In my case, I chose RGB: 255 0 0. Copacetic.

This is what my final example looks like. Pretty boring, eh?

But don't be fooled by this example's stinkiness. KPT #13 has been resurrected. This method might be unwieldy, but it works and all of those things that Kai did can now be done again.

Okay, I got off my lazy ass and did a prettier graphic. A bit too colourful for my tastes, but it is prettier.

I started with some text in an Alpha channel, then did some Gauss and Plastic Wrap in a few places. Then I tossed it all into my Layered HSB rig. All in all, not too bad. Got a bit of a neon sign feel to it, eh?

Okay, so the whole workaround is a bit unwieldy. If you know your way around the Layers palette and how things work, then it shouldn't give too much trouble. I'll be the first one to tell you that it does take some getting used to.

There are some ways to optimize it a bit. You can cut down at least one Layer, in partictular the Saturation Layers.

1) One Layer for Sat, and set to Saturation. These means black, white, and shades of gray will have Sat: 0. Then, to have higher levels of Sat, you will have to keep the above forumala stuff in mind.

2) Add an Adjustment Layer > HSB. Bring the Saturation all the way down in this Ad-Layer. The weird thing about this route is the the Sat layer is backwards. That is, black is Sat: 255 and white is Sat: 0. Backwards, but certainly functional.

Okay, so it's only getting rid of one Layer, but it's something.

If you want to be real spartan with your Layers, try adding a Hard Light Layer above the Hue rig. That's it. You do lose some functionality, but it's still fun to play with. If you add another Hard Light Layer, the lost functionality is restored in a funky manner. I'll leave it to you to figure it out.

Kai has got a lot of fun things to try in his tutorial. I recommend playing with those ideas. I also recommend tossing in a photograph or two. Mix it up and make it interesting.

play.fiddle.learn