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Author Topic: Basic Panel vs. Adjustment Brush differences?  (Read 1154 times)

Redcrown

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Basic Panel vs. Adjustment Brush differences?
« on: May 13, 2016, 01:38:29 PM »

Something I just noticed... the "Blacks" and "Whites" in the Adjustment Brush are much stronger (and slightly different) than the same adjustments in the Basic panel. All others are virtually identical (Exposure, Contrast, Hightlights, Shadows).

Sometimes I want to make an adjustment on all but a small portion of an image. So I make a global adjustment in the Basic panel, and then use the Adjustment brush to "back off" the adjustment in small areas. I dial in a value the exact opposite of the Basic panel adjustment. Much easier to paint out 10% of an image than paint in 90%.

That works well on all but Blacks and Whites. A Basic Panel +50 is not the same as an Adjustment Brush +50, so an Adjustment Brush -50 does not offset a Basic Panel +50. In one quick test, a Blacks -80 in the Adjustment Brush equals a Blacks -100 in the Basic Panel.

Just a curious discovery.
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Slobodan Blagojevic

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Re: Basic Panel vs. Adjustment Brush differences?
« Reply #1 on: May 13, 2016, 01:51:23 PM »

Since version 2012, adjustments are relative, i.e., interdependent on any other adjustments. It also stands to reason that a local adjustment may not be the same as a global one, given the differences in overall tonality distribution (histogram).

Redcrown

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Re: Basic Panel vs. Adjustment Brush differences?
« Reply #2 on: May 13, 2016, 04:00:38 PM »

Slobodan,

I understand that V2012 introduced some "image dependent" logic in some adjustments. But I believe that logic is only in Highlight and Shadow recovery. (Learned about Laplacian filters in a past LuLa thread).

Simple testing seems to confirm that. Equal adjustment values in the Exposure, Contrast, Whites, and Blacks adjustment will move a pixel from "X" to "Y", regardless of the tones that surround that pixel and regardless of the overall tonal range of the image.

The same is not true for Highlights and Shadows. For the same adjustment values (-100 to +100) , these two adjustments will move the same pixel starting value a different amount, depending on other tones in the image.

But on the same image, the same adjustment value for Highlights or Shadows will produce the same result, regardless of whether the adjustment is made in the Basic panel or with an Adjustment Brush. That is true for Exposure and Contrast as well and "stands to reason." But it's not true for Blacks and Whites, which does not seem to stand to reason. 
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