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Problem with Brightness/Contrast

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Old 07-16-2006, 07:18 AM
hpycmpr hpycmpr is offline
Join Date: Feb 2005
Posts: 36
Good examples to support my question

My following post got only a single response, so I'll use the corrections here to illustrate my points.

I often use Flora's method of Screen (or Multiply) blending and painting over the layer mask for tonal correction. But as pointed out, the floor color becomes distorted. To correct that color would need another adjustment step.

I find Kraellin's first correction losing a lot of contrast that is in the original. To recover that contrast would also need another adjustment step.

My list of tonal adjustment methods all seem to have one or both ot these problems. For each image, I have to cycle through different methods until I find one that works the best for that image. Hence, my question remains:

"Is this a case of "you can't have it both ways", or is there a better method?"

I do not mean to be critical about the posted corrections here. I can't do it any better and my comments are just for illustration purposes.
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Old 07-17-2006, 11:04 AM
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Flora Flora is offline
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Join Date: Mar 2002
Location: Milan, Italy
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Hi hpycmpr,

...hope I've understood your question:

you wish to know if there is a method to adjust exposure without losing definition and correcting colours in one go .... right?

The only option (in PS) I know of, that gets close to that, is the Shadow/Highlight Adjustment .... (available only from PS CS upwards) ...

The Shadow/Highlight Adjustment gives you control of:

* Amount,
* Tonal Width,
* Radius
for correcting shadows and highlights...

* Color Correction (you can only increase or decrease the overall Saturation, though)
* Midtone Contrast.

It's really a great Tool, but, sometimes, the colours have still to be corrected by means of other Adjustments...

Originally Posted by hpycmpr
But as pointed out, the floor color becomes distorted. To correct that color would need another adjustment step.
... As for this point, however, I don't think that the brightening manipulation was the cause of the colour distortion ... I think that the discoloration was already there, hidden by the shadows, and it simply became visible when the shadows were lifted ....

The method I used for this restoration, was limited to the shadows which I had previously selected ... (the reason behind this selection was exactly to not lose definition in the lighter parts of the image) ....

It gave me good results for the definition (particularly after refining the mask) and I've tried to correct the colours as well by tweaking the individual channels. Wasn't happy with the results I was getting, so I opted for a completely different colour correction Tool ... thus adding a second step to the procedure...

Originally Posted by hpycmpr
is there a better method?
... I have been working, on and off, on an alternative method which gives better control over the colours ... but it is also limited to either shadows or highlights separately and it also consists of two steps ...

Last edited by Flora; 07-17-2006 at 11:09 AM.
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Old 08-01-2006, 08:03 AM
hpycmpr hpycmpr is offline
Join Date: Feb 2005
Posts: 36
Can't have your cake and eat it too

Flora, thanks for the response.

I stand corrected about the color cast. It is indeed hidden in the shadow in the original.

The S&H tool works well, but I find the default b/w points too drastic. For example, if b/w points are set prior to running S&H, these points will have to be reset again.

After much researching, I found the following excellent article about the pros and cons of each tool for shadow and highlight correction. It addresses exactly what I was looking for, namely, how each tool can correct something at the expense of losing something else. The author refers to these as "expansion" and "contraction". Most books and tutorials only talk about how each tool can achieve a desired correction, but fail to mention the negative side effects.

As I suspected, you can't have your cake and eat it too. Or maybe you can, if you have two cakes, i.e. merging two images as described by the author.
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