Photoshop Histogram

Apr 25
2011

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photoshop histogram
What do color histograms measure?

I am doing a science fair project on dyes and what natural dye makes the most intense color. On Adobe Photoshop Elements I got a histogram that gave me a number for the color of the fabric that I had dyed. What do color histograms measure? What can I use to measure the intensity of the fabrics color?

Over on the right side of the Histogram is "More". Click on it and then click on Histogram Info.

Here's a search of Norman Koren's website with some information re histograms. Since you'll probably need the URL's for your bibliography, I thought this was the way to go. You can also just google Histogram for more information.

http://www.google.com/custom?q=histogram&sa=Google+Search&cof=LW%3A200%3BL%3Ahttp%3A%2F%2Fwww.normankoren.com%2FNLKphotologo.gif%3BLH%3A61%3BAH%3Acenter%3BS%3Ahttp%3A%2F%2Fwww.normankoren.com%3BAWFID%3Acab4085a354f656f%3B&domains=www.normankoren.com&sitesearch=www.normankoren.com

Now, measuring the intensity might be a tad bit more difficult. There are instruments, spectophotometers, that might be useful but your school probably doesn't have any and won't buy you one. Here's some information from a previous answer. Read all three answers. The last one has some information on getting a hand-held or used model.

http://answers.yahoo.com/question/index?qid=20080614030504AAMMhhs

I think you can use the Histogram if you set the Channel to Luminosity. I just did a little experiment myself to see how it would work. I made 5 little rectangles and, using purple on the Color Picker, selected the color in the upper right corner (the middle box), took 2 samples going down the right side toward Dark and 2 samples going across the top toward white. There's only one line for each sample in the Histogram so the mean is the luminosity. (On my example below, you'll see two lines in the Histogram and a mean that's different than the one I typed in the darkest box because the black of the type is represented.) Luminosity measures reflected light. Darker colors will absorb more light and reflect less light than lighter colors will. A more intense color may absorb more light. You'll have to do an "assay", a little pre-experiment, to see if this works for you. Don't forget to include the assay in your write up.

http://www.flickr.com/photos/22020217@N05/4148130479/

Try it with some of your fabric samples. Don't forget that in order to compare them using Elements, you're going to have to photograph them in the same lighting conditions.

Good Luck! This sounds like a wonderful project.

Adjusting Levels and Using the Histogram in Photoshop

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Welcome fellow Photoshop artist! I hope you find the Photoshop Histogram information that you are looking for. Below are some other Photoshop Histogram products at a "steal" which you might want to check out.