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what happens to the histogram

Posted: Wed Feb 19, 2003 11:32 am
by gina
HI,

I just installed the colorwasher demo and so far the results are really great! In a flash it even got a picture better I had been trying to corect for hours in seconds! I wonder though what happens to the histogram when I bring the image back in photoshop. WHen I have been using levels and tweaking the histogram, it is stretced and you can see empty lines in the histogram where you have lost a part of the information(or so I read somewhere). Is this the same with colorwasher or are you using different algorithms?


gina

Posted: Wed Feb 19, 2003 7:38 pm
by HaraldHeim
Basically such a "chopped" histogram isn't something to worry about. Only if the effect you applied with the Levels tool was quite extreme, it can mean that some essential image information was lost. But that is only seldom necessary or the case. The number of colors that are used in the image decreases, but usually not dramatically and it isn't recognizable with the bare eye.

ColorWasher has a check box called Histo Fix. Activating it makes ColorWasher fill the gaps in the histogram. This has the effect that the number of color that are used in the image is increased (instead of decreased), e.g. from 200,000 to 300,000 different colors. But you won't be able to tell the difference with the bare eye.

I can only recommend to use ColorWasher's Histo Fix if you don't want to save the image as a JPG, because it increases the JPG file size. Processing the image further with other tools, can mean even more histogram gaps or loss of color. So the Histo Fix option lets you prevent that or soothe it.

thanks

Posted: Thu Feb 20, 2003 1:17 pm
by gina
thanks for the info harald!


gina