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Question by jones
Submitted on 8/18/2003
Related FAQ: colorspace-faq -- FAQ about Color and Gamma
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How to achieve "AutoLevels" and "Auto contrast" features of photoshop by VC++.
I need to enhance imgages applying "AutoLevels" and "Auto contrast".
I want to do programmtically by c++.

any help apprecite.


Answer by CCs
Submitted on 3/10/2006
Rating: Not yet rated Rate this answer: Vote
Description from Photoshop:

"Comparing Auto Contrast and Auto Levels may further clarify how Auto Contrast affects your images. Auto Levels corrects images with an overall color cast. To do this, it analyzes each channel individually and maps the pixels with the lowest values to 0 and the highest values to 255. The new Auto Contrast command, on the other hand, adjusts poor image contrast based on pixel luminosity, which it calculates based on a weighted average of the RGB values (remember, you asked!). It disregards the first 0.5 percent of the range of white and black pixels to ensure that it's getting representative image areas, and maps the lightest pixels in the clipped range to white and the darkest pixels to black. Highlights then look lighter and shadows darker, for finer overall image contrast."


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