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d&b and hue/saturation shifts

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  #21  
Old 07-26-2009, 02:29 PM
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snook305 snook305 is offline
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Re: d&b and hue/saturation shifts

Funny you guys are talking about this as I just went through Dan Margulis newer video tutorial and even he who got everyone on the LAB boat is starting to doubt all his initial test on lab. It is very interesting stuff.
You might want to check it out. You can find it on Scott Kelby's site. He really goes into lumonisoty mask quite in depth if you are interested.
Also I always put my sharpening layers on luminosity mode as that is supposedly the same as going to LAB.
Snook
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  #22  
Old 07-26-2009, 03:26 PM
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Re: d&b and hue/saturation shifts

Snook & Mark, I think Dan Margulis never believed that LAB was the best solution for everything and he was careful to point out in his book and in subsequent writings, all of the dangers and disadvantages.
I use LAB when it makes sense or when it would take considerably more effort or it is impossible to achieve the same result in another color space.
I still do most of my work in RGB where I find it as fast or faster to do things like Sharpen with Edit>Fade to Luminosity among other tricks.
However, for the issue raised by Mike in this thread, I will defend the use of a 50% overlay (in all of the 6 contrast modes) in LAB as a better solution to doing the same in RGB. And I believe it to be a faster / more efficient way than using darkening and lightening Curves with set to luminosity with layer masks in RGB.
Mark, yes, I saw Der_W's thread. FYI, in any of the 6 contrast modes in LAB, you can paint with Black and White brushes on the 50% gray layer and observe that only the L channel is modified; the Aand B channels are never changed. The 50% gray layer is the adj layer and the mask and the curve.
Regards, Murray
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  #23  
Old 07-28-2009, 12:01 PM
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Re: d&b and hue/saturation shifts

I'm in a hurry but...for the destructive part about RGB->LAB->RGB, do an action (8bit mode) run 100 times --> noise everywhere. Do it in 16 bit -> no noise.
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  #24  
Old 07-28-2009, 01:40 PM
rcc123 rcc123 is offline
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Re: d&b and hue/saturation shifts

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Originally Posted by ApWizard View Post
I'm in a hurry but...for the destructive part about RGB->LAB->RGB, do an action (8bit mode) run 100 times --> noise everywhere. Do it in 16 bit -> no noise.
Try turning off "Dither" if you're going to go back and forth 100 times for no reason. I think you'll see the results virtually match the 16 bit RGB to LAB conversions (that by design don't use dither). Dither adds a tiny bit of noise to prevent banding of 8 bit images. It's very effective when used in small amounts, but not meant to be applied 100's of times to a single image.

Ric
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  #25  
Old 07-28-2009, 02:20 PM
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Re: d&b and hue/saturation shifts

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Originally Posted by rcc123 View Post
Try turning off "Dither" if you're going to go back and forth 100 times for no reason. I think you'll see the results virtually match the 16 bit RGB to LAB conversions (that by design don't use dither). Dither adds a tiny bit of noise to prevent banding of 8 bit images. It's very effective when used in small amounts, but not meant to be applied 100's of times to a single image.

Ric
Turning off Dither really helps and improve image quality in respect of having it turned off. In a pure technical analysis (maybe in pixel peeping) the image is degraded indeed.

Then yes, converting 100 time back and forth is a little compulsive :°D
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  #26  
Old 07-30-2009, 01:15 AM
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Re: d&b and hue/saturation shifts

The straight dodge and burn does always cause some cross color artifacting...sometimes quite annoying.

Every skin imperfection is created because there is a differential between lightness and darkness over the surface of the zit, scar, wrinkle or pore. When you light across a pimple or a pore you get a lighter area and a darker area that alerts you to the presence of the imperfection.

Another way to approach D+B is to use the lighter skin color to paint the darker side of the imperfection so it approaches the lightness of the other side. Alternately if you darken down a highlight tone on one side of a blemish... then the contrast difference between the light and dark areas stops screaming at you to "look at me" there is a bump over here.

By using the color sampling tool it is possible to get a handle on what brightness and color the darker side of pores is...and what the light side of pores or blemishes are. Then you can use an adjustment layer levels or curves function to create that correction color for you. You paint the lighter correction color on the darker edges of the blemishes and the darker correction color to tone down the highlight side of the boundry.

You may have to sample somewhat often...but that is good... because then you retain the character of the area of skin you are working on...maybe that area is a highlight area or maybe that patch is part of the shadow area.

D+B is an insidiously long and frustrating process...and just like any other part of Photoshop...sometimes it takes a long time to master...and some good Artistry talents to get a good effect.

Not everybody has the patience, the small motor finger control, or the ability to stay on task for such long periods of time...let alone the exact methodology of how to get great results. Oh, I forgot to add...the ability to see the big overall picture while looking at individual pixels at 400% magnification. Add on top of all of this...the fact that the dodge and burn tools leave an ugly mis-color artifact if done too deeply...No wonder most of us give up and only wish we could do it well. D+B aint all of what its cranked up to be.
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  #27  
Old 07-30-2009, 09:03 AM
otisXmike otisXmike is offline
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Re: d&b and hue/saturation shifts

thanks for all the replies. There is some good info here and I will try all the different methods. I've found that a lot of the problems that I initially explained have a lot to do with the actual photo that you're using. I don't have the best quality photos to practice from, as I'm using photos provided in the forums here and at modelmeyhem; though I have had success with some that I've downloaded.

Thanks, Mike
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