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How to achieve Photoshop CS3+ style brightness?

Nov 17, 2011, 15:25 (This post was last modified: Nov 17, 2011 16:08 by Hendu71.)
Post: #1
How to achieve Photoshop CS3+ style brightness?
So, I'm a Photoshop convert to Gimp (though hardly a photoshop guru), and I have a question.

Okay, if you know CS3 or newer, you know that the brightness slider has a different effect than Gimp 2.6. In Gimp, adjusting the brightness to brighter essentially has the effect of putting a white transparent overlay over the picture that gets more opaque the "brighter" it gets. It basically looks like a grayish film is over the whole picture.

This is the same effect as the "Legacy" brightness you can select in Photoshop, which is still available but not default. The default brightness slider in newer versions of Photoshop, is not necessarily better, but is definitely different, and very handy for beginners for certain things.

Basically, as you adjust the brightness higher, it appears like the exposure is cranking up. Like a persons face will become washed out (as if they were shot with a flash nearer their face), but the shadows stay just as dark.

See more here if I'm not clear:

http://www.photoshopessentials.com/photo...-contrast/

Now, I know in Gimp, you can adjust the Levels to achieve a similar effect. However, this requires a lot of tweaking and more complicated than just sliding a bar back and forth. And I'm not very good at that. Plus, you don't know if you got it exactly the same as Photoshop's results.

So, is there a simple way to do the same thing? A plugin perhaps? This is perhaps one of the biggest functional gaps I've run into so far between Gimp and Photoshop. Any help will be appreciated.
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Nov 17, 2011, 18:14 (This post was last modified: Nov 17, 2011 18:15 by ofnuts.)
Post: #2
RE: How to achieve Photoshop CS3+ style brightness?
(Nov 17, 2011 15:25)Hendu71 Wrote:  So, I'm a Photoshop convert to Gimp (though hardly a photoshop guru), and I have a question.

Okay, if you know CS3 or newer, you know that the brightness slider has a different effect than Gimp 2.6. In Gimp, adjusting the brightness to brighter essentially has the effect of putting a white transparent overlay over the picture that gets more opaque the "brighter" it gets. It basically looks like a grayish film is over the whole picture.

This is the same effect as the "Legacy" brightness you can select in Photoshop, which is still available but not default. The default brightness slider in newer versions of Photoshop, is not necessarily better, but is definitely different, and very handy for beginners for certain things.

Basically, as you adjust the brightness higher, it appears like the exposure is cranking up. Like a persons face will become washed out (as if they were shot with a flash nearer their face), but the shadows stay just as dark.

See more here if I'm not clear:

http://www.photoshopessentials.com/photo...-contrast/

Now, I know in Gimp, you can adjust the Levels to achieve a similar effect. However, this requires a lot of tweaking and more complicated than just sliding a bar back and forth. And I'm not very good at that. Plus, you don't know if you got it exactly the same as Photoshop's results.

So, is there a simple way to do the same thing? A plugin perhaps? This is perhaps one of the biggest functional gaps I've run into so far between Gimp and Photoshop. Any help will be appreciated.
For this kind of things I start the Levels dialog and play with the middle handle just below the histogram. Period. (this is nothing more than adjusting the "gamma").

As to getting exactly the PS results... well, use PS Smile But IMHO, when one gets really picky about the image exposure, this requires more than a single one-size-fits-all slider.

However... doing this on a JPEG image has side effects because with 8 bits per channel you quickly generate "banding". If you are serious about the general rendering of your images, do the general brightness/color/contrast stuff on "raw "files, that have more bits/channel (10 to 14).

Now answering your questions on
https://Gimp-Forum.net
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Nov 21, 2011, 11:36
Post: #3
RE: How to achieve Photoshop CS3+ style brightness?
Well,

if there is no such plugin, somebody can programm it.

I see no technical obstacle to achieve such functionality in gimp, only that a programmer would need formulas.

Some shortcoming of current brightness is given by gamma - or rather the brightness function ignoring gamma. Obviously if you move pixels in range 0-80 to 150 - 230 (= increasing brightness), the visual difference between the two values will be much smaller while mathematically it is still 80 points.

Also I noticed that contrast in that new behavior working like this: stretch the curve untill (let us say) 0.5 % of dark pixels and 0.5 % of bright pixels will get out of range - but no more, than manipulate the curve...

Do you really believe that such functionality is badly wanted by gimp users?
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Nov 21, 2011, 13:36
Post: #4
RE: How to achieve Photoshop CS3+ style brightness?
(Nov 21, 2011 11:36)TiborB Wrote:  Well,

if there is no such plugin, somebody can programm it.

I see no technical obstacle to achieve such functionality in gimp, only that a programmer would need formulas.

Some shortcoming of current brightness is given by gamma - or rather the brightness function ignoring gamma. Obviously if you move pixels in range 0-80 to 150 - 230 (= increasing brightness), the visual difference between the two values will be much smaller while mathematically it is still 80 points.

Also I noticed that contrast in that new behavior working like this: stretch the curve untill (let us say) 0.5 % of dark pixels and 0.5 % of bright pixels will get out of range - but no more, than manipulate the curve...

Do you really believe that such functionality is badly wanted by gimp users?
The functionality is there, in the middle handle of the "Levels" dialog. IMHO, given the 8-bit limitation, all these adjustments should be done in one go, so it's either the Levels dialog or the Curves dialog. They can both be used to adjust gamma and contrast, with more freedom than the Brightness/Contrast dialog.

Now answering your questions on
https://Gimp-Forum.net
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Nov 23, 2011, 15:36
Post: #5
RE: How to achieve Photoshop CS3+ style brightness?
Hendu71,

I just started development of more-less such plugin, if you are interested to test it go to
http://code.google.com/p/safe-brightness...loads/list
there is only one file to download. Installation instructions are in README.txt in the pack
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