Color Separatoin | High Contrast B&W

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mikeincousa
Posts: 4
Joined: Mon Mar 04, 2019 1:53 am

Color Separatoin | High Contrast B&W

Post by mikeincousa » Sat Mar 16, 2019 12:27 am

:D
Hello again,

I am starting to learn the app. Great fun. Great code. Thanks for all the work behind it.

I managed to rotate the attached test image from landscape to portrait. Ultimately I will want to rotate such images in a batch mode.

I am seeking something like a eye dropper (like in Gimp I think?) that I can use to identify a color, then with that HEX value change that color to another one. Maybe I am ahead of myself?

More specifically for the attached test example, I am seeking to turn it into a high contrast B&W image like one would get from a commercial copy machine.

I am seeing three colors: the gray background; the blue URL links; and the lettering. Maybe there are more? Is there a way to get a frequency distribution type mapping of the colors? I could post a *.pdf of the original if that would help: let me know. note parts of the image may not be in the sharpest focus, but that does not matter for this question.

BTW. The contrast is set by the lighting and camera. This is a color rendering. I have not seriously tried the B&W mode yet: it would likely improve the contrast on this image somewhat but I do not think it will directly bring the deep white and deep black very high contrast that I seek. Again ultimately I would like to do this in a batch if possible.

FYI: I am using LED desk lamps for the illumination. This is a first for me. They seem to have a strong blue cast and I am wondering if that is part or all of graying of the image? Maybe there is a way making a global color correction for all such images?

Thanks for any thoughts and your ongoing support.

Michael
Attachments
Reading.chart.2.IMG_6880.jpg

cday
XnThusiast
Posts: 1959
Joined: Sun Apr 29, 2012 9:45 am
Location: Cheltenham, U.K.

Re: Color Separatoin | High Contrast B&W

Post by cday » Sat Mar 16, 2019 8:31 pm

mikeincousa wrote:
Sat Mar 16, 2019 12:27 am
I am seeking something like a eye dropper (like in Gimp I think?) that I can use to identify a color, then with that HEX value change that color to another one. Maybe I am ahead of myself?
There is likely a way to see the value of particular pixels, but I don't think there is a way to globally change values using that value; someone please correct me if I'm wrong...

More specifically for the attached test example, I am seeking to turn it into a high contrast B&W image like one would get from a commercial copy machine.
I would normally suggest using a levels adjustment, possibly after converting the image to grayscale. If your images have similar properties, you can then use the optimum settings you determine to batch convert other images. The recently added curves adjustment could also be used if you are familiar with it, but probably isn't needed.

The ultimate result that can be obtained using levels is limited by the evenness of the illumination of the page, but your posted image seems unusually evenly illuminated considering the setup you described. I'm attaching an enhanced copy of your image to give an indication of the results that might be possible.

I am seeing three colors: the gray background; the blue URL links; and the lettering. Maybe there are more? Is there a way to get a frequency distribution type mapping of the colors? I could post a *.pdf of the original if that would help: let me know. note parts of the image may not be in the sharpest focus, but that does not matter for this question.
There should be somewhere, but if levels works well enough that would be the easiest method I think.

FYI: I am using LED desk lamps for the illumination. This is a first for me. They seem to have a strong blue cast and I am wondering if that is part or all of graying of the image? Maybe there is a way making a global color correction for all such images?
I can't advise on that but support should be readily available if you post that question on the dedicated scanning forum I mentioned above, and in general I think you are likely to get more support there than on this forum other than for issues directly related to this software, where few members provide general support.
Attachments
Reading.chart.2.IMG_6880_Levels.jpg

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