Topic awaiting preservation: HSB junk (Page 1 of 1)

Too much stuff, so I'm going to leave some loose ends for now. Just don't have the strength right now for some of the little things.

KPT 13 Revisited
In particular, the Gradient Map trick for Saturation.

Exploring HSB in a Photo

Raw Hue
New Layer
Fill with 50% grey
Set to Luminosity
Ad-Layer > HSB and use Sat = 100

Should be looking at a beautiful rainbow of colours.
Recommend copy merge, paste, trash some layers.

Raw Lum
New Layer
Fill with 50% grey
Set to Saturation

Copy merged, paste, trash as prefered.

Raw Saturation
This is the one that has been giving me problems. Some weeks ago I was on the right track, but a stupid little mistake sent me into a tizzy. Silly me.
Adjustment Layer > Selective Colour
For all major hues, RYGCBM, set Black = -100%.
For whites, neutrals, black, set Black = 100%.
Good idea to save ASV file.

Copy merged, paste, trash as prefered.

Now have all 3 components separated. Go ahead and put them back together using blending modes - don't forget the G-Map trick for Sat. Should be damn near pixel perfect. I estimate error at around 3%.

Good for?

More channels for ChOps. So far I've had pretty good success with these tossed into the ChOps mix as needed.

Or an exploratory into some colour things. You know, just dinking around and making observations. Never hurts.

Also good for matching fleshtones visually in separate parts. No real need to eyeball numbers when you can eyeball some grey or raw hue. Man, *so* much easier to see the needed tweaks.

Recommend recording your own Actions.

One thing I'm really digging is raw hue + Selective Colour. This is proving to be a damn fine combo. In all of the time that I've been around, I can't recall any real mention of using Selective Colour. Once you start getting the hang of it, Select > Colour Range is more bleh than usual. Why, you can even soft selection based on hue with all of the usual tweaks. I would call that a good deal.

Try this over a photo:
Ad-Layer > Selective Colour
Yellow: Black = -100%
Everything else: Black = 100%
Between photo and SC, Ad-Layer > HSB
Mess with sliders and even the drop-down.

For ChOps, I like to use Layer Sets and let blending modes do most of the work.
Let's say that I want to intersect a range of R with a range of G.
Well, cut-n-paste both of them into a layer set and set the top one to Multiply.
Then clip Ad-Layers as needed and tweak away.

Of course, other blending modes come in handy as well.
For example, tweak the grey point of a layer and then Linear Light it with itself.

Um...
I'm about to fall asleep right on my keyboard.

Gradient Maps

A G-Map can be used to do exactly what Level3 does.
black - grey - grey white
Silly me.

Another G-Map that I find very useful is:
black - white - white - black

A G-Map can also be used as a mix between Levels and Curves. Levels can't do some of the tricks that Curves can do. However, as much as I adore Curves, sometimes the b-spline gets crazy with the Cheese Whiz then things are a little tight.
Answer? Use a G-Map.

Back when I was playing with the PS CS trial, the first thing I tried was Colour Match. While it is cool, I find it lacking. I does it's job just fine, but things can get messy when the Cheese Whiz comes walking in.

If you were paying attention, you can use seperate channels, intersections, and smart adjustment layers, to do what Colour Match does - but better.

Okay, so I don't have PS CS's Colour Match handy to seriously back that up.
But it is nice to have the same functionality in a manual form with visual tweaks. Hard to beat visual tweaks when they are on several levels.

Why, I almost want CS again just to see if I can mix my ideas with Colour Match.

Back to laundry.

Manually Pumping Up Saturation Contrast for ChOps and Things w/out the Jaggies

Ad-Layer > Curves
Manually tweak contrast in each channel.
Give Comp RGB one final tug after R, G, and B.

Ad-Layer > HSB
Sat = 100%

Ad-Layer > Selective Colour to greyscale the sat.

It's a thing of beauty.

Very very very very interesting.
I think I'll play with this a little later tomorrow.

Go, TP.

Using the above material, here is an example.
Not the greatest example in that Pen would work great for this.
However, imagine if those similiar shades of brown were whispies.



Grabbed Sat + Lum.
Tweaked both with a clipped G-Map (black - white - white - black).
Set the top one to Multiply to intersect.
Other tweaks as needed.

With another tweak or two, could also grab the shadow.

Even though I used Sat + Lum, I did check Lab to see if any of those channels would be good. Not in this case, but it's good to check.

Man, I gotta get some sleep.
This stuff has kept me up for about a week now.

(Edited by warjournal on 11-01-2004 20:34)

For the selective color, you use absolute, or relative?

So selective color was the answer to get SAT. I always wondered. How the heck did you find that?

(Edited by sPECtre on 11-03-2004 21:55)

D'oh, I get the correct image, just with the hue and luminosity layers, sat greyscales it... what Am I doing wrong.
food for thought, definitively...

Pierre Courtejoie

Selective Colour > Absolute. I think that's right. Whatever the default is.

How did I figure it out?
Well, when I failed miserably with my usual Bag o' Tricks, I took a romp through Image > Adjustment and took a closer look at the tools I wasn't familiar with.
Selective Colour just happened to have what it takes.
All major hues and some extra things just right for the job.

Unfortunately, when I first looked at SC, I did something terribly wrong. Wasted a lot of time trying to figure things out. In a fit of desperation, I went back to SC and found my original mistake. Really simple mistake, too. Yeah, I'm an idiot sometimes.

Spec, try loading this file into SC:
extractsat.asv

If that doesn't work, I'll need you to get very explicit with your steps to get raw Sat.
Or you could just get explicit.
And dance.

Ah, ok, from your explanation, I had only the black at -100, not all the composites.
Now, with just the BG and the selective color adj layer, I create a blank layer, and CTRL+ALT+SHIFT+E to get a copy merged. I created the hue and lum layers as explained.
I then give the appropriate blending mode to each channel. hue for hue, etc...

However, when they are all showing, they whould recreate the image, which they do not. Even with the BG image (a photo)under+h, s,l, sat greyscales the image. And having hue and lum only gives the proper image...

here is the psd:

http://home.scarlet.be/~pc980170/IMAG0005.psd

Pierre Courtejoie

The problem is with the Sat layer.
You see, it's grey and all shades of grey are sat=0.
You have to use the Gradient Map hack to fix it.

Clip a G-Map to the Sat layer.
Make one end of the map any shade of grey.
Make the other end of the map a pure hue. For example, RGB=255,0,0.


Just past half-way down I talk about this:
http://disk919.com/tech-slop/kpt13revisited/index.shtml

Ah, ok! so the way to "get" the S values are as explained, but they need to be "converted" to the proper sat values using the G-map...

Still, it is strange that the image "works" without it...

Now, you've got ME rambling...

Pierre Courtejoie

quote:

---

Still, it is strange that the image "works" without it...

---

In your PSD, there is a reason that it "works" without it.
It's because you have the hue layer set to Hue and the lum layer set to Lum.
The saturation is coming from the original photo at the bottom.

When doing this stuff, I prefer to have the hue layer at the bottom and set to Normal.
Then layer the lum and sat on top of that.

Here's kind of a neat trick for tweaking Sat.
Sat in photo is too high, but using HSB to bring sat down washes too much of the photo out.
Sat is too high in the general highs, but just fine in the general lows.
So, extract the sat and set up the G-Map.
Between the sat layer and G-Map, clip a Curves or Levels Ad-Layer - but use luminosity as a mask.
Now you can adjust sat based on lum highs.
Or you can invert the lum mask and tweak the lows.
Or you can...

blah blah blah

I know you are smart enough to figure out such things.

I suppose you could load the lum as a mask for an HSB Ad-Layer and slide the S around.
But the long way is so much fun to play with.
Your Bag o' Trick can never be too big.

(Edited by warjournal on 11-04-2004 14:12)