Topic awaiting preservation: Local Contrast - one of those days (Page 1 of 1)

Been thinking about 'local contrast' for a bit. Much along the lines of Adaptive Equalization, but softer.

So I started experimenting with Median, Gaussian, and Smart Blur.
From there, I manually chopped out the lighter parts and darker parts.
Then I slapped them together appropriately.
Result?
If a given pixel was high compared to it's neighbors, then it was made even lighter.
If a given pixel was darker compared to it's neighbors, then it was made even darker.

Lots of work, but so far so good.

Then I got to thinking about frequency. What I was effectively doing was taking the high frequency details and amplifying them. Which, in turn, got me to thinking about a particular High Pass tutorial.

See: The Power of the High Pass Filter.

Okay, time to try High Pass instead of all of the ChOps that I was doing.

Copy photo.
Filter > Other > High Pass
Set blending mode to Hard Light or Linear Light or some other 50% mode
Tweak Opacity

Bingo.
Slap forehead.
Sigh and wipe brow.
Jump up-n-down and kiss the neighbor (the cute one).

Out of curiosity, I hit Google.
The first hit: http://www.luminous-landscape.com/tutorials/high-pass-sharpening.shtml

All of that work and the answer was simple... almost too simple.
dun dun dun duuun

Long way? Short way?
Hell, I don't know.
But it sure is fun.

Yeah, one of those days.

play.fiddle.learn

High pass seems to be good to use when it comes to masking one's unruly hair . Whatever tools to use, it is bound to lose many strands of hair that makes the picture unnatural after blending.

A venue for sites with cool logo
http://www.pretty-logos.com

(Edited by whl626 on 11-21-2004 02:47)

No! I don't want any more tricks for unruly hair!
Aahhh!
Must... focus... on... other things...!

Did a little more playing with High Pass and I'm very pleased. Not hair related, but fixing interpolation related things. One of my favorite things is to tear things apart - including photos into various channels. However, when you do that and start operationg, you can get nasty stair-stepping. The data just isn't always there, and PS does what it's told.

Gaussian Blur out the window.
I couldn't even get Median and/or Smart Blur to play nice.

New plan:
Protect the edges from blurring.

I remember reading a quick thing about protecting the edges using Smart Blur. Basicall, Smart Blur is used to find the edges, then that is used as a mask. I tried it and didn't really care much for it because of the lines themselves. Or maybe I just need more practice with this route.

Stylize > Find Edges just plain sucks.

Although, one variation that I haven't tried is Filter > Other > Custom with a good kernel.

Then it occurred to me about frequency again.
I don't want to just take out the high detail frequencies, but also kind of use amplitude as well. The higher the amplitude in the high frequencies, the more protection.

Something like:
Copy original photo.
Filter > Other > High Pass. I like to use around 3, but feel free to experiment.

This will be in RGB and needs to be greyscalified with intent.

Image > Adjust > Channel Mixer
Use Monochrome and make R, G, and B 33%.

Go ahead and Auto Level it.

Now for Curves.
Why?
Because right now, the greys are the parts that need to be blurred, while the black and white parts need to be protected.

Image > Adjust > Curves
Bring upper-right all the way down to zero.
Add an anchor dead center and bring it all the way up to 255.
Should like a hill or a mountain or something.

Or, if you don't want to use Curves, use a Grandient Map that goes black - white - black.

You should be left with a mask for blurring.

Man, it's a thing of beauty and I'm *very* happy.
Kind of makes me wish I had PS CS just so I could try this with Lens Blur. Just might have to hijack a machine for a few minutes...

Quick example of High Pass mask blurring.

Took Biker Chic and extracted hue just in case I felt like making a selection based on hue.
High Pass = 4
Gauss = 9

left side = bad
right side = *much* better