Color correction modes 2  

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AlexandreJ
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Color correction modes 2

by AlexandreJ » Thu Feb 23, 2006 5:26 pm

Here's a full page on this sample :
Advanced color correction

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GURL
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Location: Grenoble

by GURL » Fri Feb 24, 2006 9:06 pm

In this tutorial, just under the "HDR color correction" sub-title ,there is a Macromedia movie, but it don't play.

To see it I can can left click the image and select "Play" (...ou plutôt "Lire".) Another solution is to scroll down to this image quickly when the web page is opened...

About Macromedia Flash Player , my situation (XP + IE 6.0 or FireFox) is: "You have version 8,0,22,0 installed".
________________

Alexandre wrote:BTW : the histogram is working like photoshop level in two pass : first pass applied on each individual channel (red, green, blue) and a common final pass for every color. This isn’t well known and is in fact the cause of many misunderstanding of the level tool. It’s not a single operation on pixel, it’s a double operation on pixel.

The reason why those two pass are useful to avoid color clipping and the difference between RGB histogram and luminance histogram are explained in this short and well illustrated tutorial: http://www.cambridgeincolour.com/tutorials/histograms2.htm (Sean T. McHugh's Cambridge in colour web-site.)

The same and not well known problem occurs when the Photoshop Curves command is used : as an example, changing the green curve while leaving the RGB curve unchanged is either impossible (a drastic change like G = 0 is impossible to recover!) or necessitates small changes to the red and blue values of most image pixels...

This suggest that using Lab mode and restricting user access to L could result in an easist interface (easiest for the user, that is) ...but I have only a keyhole view of the involved problems!
Last edited by GURL on Sun Feb 26, 2006 11:32 am, edited 1 time in total.
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