I found this from Russellbrown's site about this command
which could solve this local contrast thing.
Great tutorial Flora! I think, had you been here when I read it, you would probably have seen the veil lifted or the buzzer ding or the lightbulb above my head go off, for I had never ever EVER even thought about using shadow/highlight to help in the fixing of an old faded picture. Maybe I need to leave this box a bit more often, huh?
Thank You for a great tutorial!!
(...and for giving me my latest DUH! moment! lol)
Did quite a bit more detective work.
A great deal of basic insight into S/H comes from a basic gradient. Russell did this in this video, and I highly recommend that you do it, too. If you do this, and I hope you do, I suggest setting the gradient's Smoothness to 0%. Don't want that extra B-Spline messing with your eyes.
When Flora says "bring them closer to get more contrast", what exactly does this mean?
Contrast: to set in opposition in order to show or emphasize differences.
However, the "bring closer" part is confusing. If you use Levels to bring the high and low points closer, say 64 to 193, you don't get more contrast. Rather, you get a wishy washy mess.
Now, bringing closer doesn't mean the high and low points in S/H. Rather, it's the points between the high/mid and the low/mid.
Let's say High = 255.
And Mid High = 193.
What will happen is that Mid High will be lowered while High is staying the same (or mostly the same). Since the difference between the two is now greater, more contrast. This is in line with numbers I posted earlier.
So, bringing them closer means to take the medium highs and medium lows, and bring them closer to the middle. Beer in mind that is for when you have highs next to medium highs, and lows next to medium lows.
What happens if you have medium high next to medium low? They both get closer, less difference, less contrast. Part of the fix for this is the Radius slider, which is a High Pass operation as shown by Russell. This is why you get halo when really high highs are next to really low lows. The other part of the fix is the Midtone Contrast slider. If the medium highs and medium lows get too close together, you have to "pull them back apart" to bring back contrast.
When dealing with the Midtone Contrast slider, there is something very interesting going on. If you know your orders of operations, you should be able to figure it out.
One of the major problems in all of this is how to communicate certain ideas and things. One thing I'm fond of Squish Factor, but I never really know if +Squish is expanding while -Squish is contracting, or if it's the other way around.
Lay down a black to white gradient.
Shadow/Highlight in basic mode.
Use 50% for both sliders.
When you look at the resulting gradient, what are you seeing? It looks as if the high and low ends "attracted" the grey to their respective ends, doesn't it? But what is actually happening is the grey is "attracting" the high and low to give the grey more space in the gradient, so to speak. So, do you speak in terms of algorithm or in terms of eyeballs? (This is a fight I've had many times when it comes to explaining Displace. There is what appears to be happening and there is what is actually happening.)
Can be confusing, but extreme clarification can be a good thing. I feel that this is particularly important when people take your word as bond. Yes?
I also took a very close look at the Colour Correction slider. It's a fascinating trick that I thought only I knew about. Back when I was researching colour cast, I discovered a very fascinating offset wave. Apparently someone at Adobe discovered it as well. Did I mention that it's fascinating? Completely and absolutely.
Speaking of offset, it is possible to "double-back" with Shadow/Highlight. I don't know what this particular foible is called. If you get crazy with the sliders, don't be surpised if you end up with an extra hump or two.
A great deal of what S/H does can be done with Curves, especially if you know your ChOps and custom define a few things. If you know the powerful, yet mysterious, offset wave, you can even colour correct the same way (and do a few other cool corrections).
And there you have it.
In a nutshell or something.
Last edited by Stroker; 08-03-2005 at 02:08 AM.
thank you for the great link!
I had already watched this great Tutorial by Russel Brown (I'm a big fan) ... and it was one of the things that got me 'experimenting' with PS Shadow/Highlight ....
thanks for your feedback!!! So glad you found some use for this tutorial!!!
What I'm interested in is the consequence/result of 'moving sliders' on a regular picture to see if/how moving that particular slider can help me with the problem at hand...period.
Highs=255 (difference = 255)
If I tweak and get (for example):
Highs=200 (difference = 170)
What's so confusing about that???
Not having a full knowledge of what happens 'behind the sliders', in my previous post I had already said that:
I have repeated many times in my various posts that I jus 'eyeball' ... that I don't work by numbers and (beside some basic 'numbers' corrections), I don't even try since I don't have the necessary knowledge ... I might be one of the very few here who doesn't know how to 'consciously' use algorithms ... but, usually, I am satisfied with the results I get .... and that's that.
Great tutorial Flora!
After reading all of the replies, it seems people look at photoshop in different ways.
There is the "how photoshop works" approach, and the "how to use photoshop " approach.
Personaly, I only care about how to use the program, and not so much the A+B=C meathod.
I trust Flora's word because she can back up anything she says by posting the images she works on. Unless someone can put out amazing results like she can, I don't think they have a leg to stand on.
I really don't think your family, friends, and clients are going to really give a crap that the image you restored/retouched looks great, but you can't explain to them the mathmatics of how you restored the image.
I have been using Paint Shop Pro and Corel Photo paint and a lot of plugins for years now.
Last week I purchased Photo Shop CS 2. Because of yours and others work
and tutorals. It's a foreign Program for me. I like the way you explain things
in a clear and easy to follow way. I have a lot of things to learn about PS.
Thank you for shareing your knowledge with a stranger you have never met.
Thanks for pointing out H/S. At first I was skeptical, because it simply does what curves command does - so why learn yet another tool - which often brings its own set of foibles.
The second thing I was skeptical of was that S/H works on an image layer and not as a separate layer. I always use curves adjustment as the top layer and leave its final adjustment till the end - because of banding of the histogram values. [Banding is those gaps and peaks created in the histogram, which is due to rounding of values into integers between 0-255. Information is lost and if the gaps are big enough they cause sharp transition bands in places where transitions are smooth - such as faces. Repeated use use of levels and curves on a image layer, increases banding.]
Well, a miracle happened - Highlights/Shadows does a remarkable job of smoothing out the banding in the histogram. So it does offer more than Curves. So I'll be adding it to my repertoire!
PS. For those who have nothing better to do - try the following experiment.
Open a new image and lay a black to white gradient. Then repeatedly apply level or curve adjustments on it. Watch in horror as bands show up in the smooth image.... Just imagine it happening to those lovely faces in your pictures that you keep spending hours smoothing out... Beware of the histogram chompers!!!
Last edited by lincolnF; 10-05-2005 at 04:37 PM.
Thanks for the Info.
I have a question. At which stage should one correct S/H.
I have aoften been confued by this. Also How do you know the limits with out over doing it.. For print that is..
I have sent some stuff out that I thought would be a little blown out but actually printed better?
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