Histogram Correction Question.

[jw2004]

In PS, the Output Levels can set 0 to 0 or so, the lowest and highest level can be same, but In PL, the output levels highest and lowest can't be same. Highest - Lowest must >=3.
Why?

For example, If I want to cutout something, I create a mask, I use histogram to adjust the mask to only two color, black(0) and white(255), but I can't finish it with histogram correction, because It always generate the intermediate colors between black(0) and white(255)。

Untitled.jpg

[ellhel]

Hi,

you could attach a threshold layer to the histogramm corrction.

ThresholdCut.jpg

Regards
Helmut

[jw2004]

in PS, the lowest output even can greater than the highest output, let the image invert color.

[bkh]

In PS, the Output Levels can set 0 to 0 or so, the lowest and highest level can be same, but In PL, the output levels highest and lowest can't be same. Highest - Lowest must >=3.

Same doesn't really make sense – you're asking to map the same input value to two different output values (but of course one can give a different meaning to it). Anyway, you can set input levels to 90 and 91, say. But the minimum is limited to at most 252, and the maximum value to at least 3, for some reason I don't understand, either.

For example, If I want to cutout something, I create a mask, I use histogram to adjust the mask to only two color, black(0) and white(255), but I can't finish it with histogram correction, because It always generate the intermediate colors between black(0) and white(255)。

That's what it's supposed to do (at least if you are working in 16 or 32 bit mode, anyway). Just use the right tool (threshold adjustment layer instead of histogram adjustment) and you'll be fine (works even better because you only have to set one value).

in PS, the lowest output even can greater than the highest output, let the image invert color.

Might be an interesting option, but not a strict necessity: in PL you can achieve this using a Curves adjustment layer.

Cheers

Burkhard.

[jw2004]

Same doesn't really make sense – you're asking to map the same input value to two different output values (but of course one can give a different meaning to it). Anyway, you can set input levels to 90 and 91, say. But the minimum is limited to at most 252, and the maximum value to at least 3, for some reason I don't understand, either.

You can't set input levels to 90 and 91, because the highest - lowest >= 3 too, In photoshop, highest - lowest can be 1;

histogram is a handy tool, and it seems that more people use it than curve tool.

[bkh]

You can't set input levels to 90 and 91, because the highest - lowest >= 3 too, In photoshop, highest - lowest can be 1;

Of course I can (PL 18.53 64 bit on OS X 10.10.3). Either you have a different version, or your theory is wrong. Maybe you should be a litte more careful with what you claim.

Cheers

Burkhard.

[jw2004]

Oh, maybe I should test carefully.
I test again:

In Photoshop:
----Input levels: max - min >=2
----Output levels: max - min = -255 ~ 255 ( max can less than min)

In PhotoLine:
----Input levels: max - min >= 1 and min <= 252 and max >= 3
----Output levels: max - min >= 1 and min <=252 and max >= 3