How can I measure the average color of selected areas in an image?
Asked 2/4/2017
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2 answers
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I have a scanned/photographed test print with many colored squares, and I want to measure the average color of each square as a HEX or HSV value. This is for Risograph print tests, where overprinting spot colors creates mixed colors, so I need the average color of each printed patch rather than a single pixel sample. I may need to do this for dozens of squares, so I’m looking for a practical end-user workflow in software such as Photoshop, GIMP, or another image-analysis tool, without needing to code.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
6
A more accurate sampling of the actual average would be in Photoshop, to draw a box around the selected sample (with regular marquee tool), and then use Photoshops averaging filter (menu Filters - Blur - Average). This gives one smooth solid color for the computed average (within that drawn box), so then the color picker tool will show this same average value, no matter where you click in the box you drew.
Originally by user38978. Source · Licensed CC BY-SA 4.0
user38978
9y ago
0
Generated from our catalog & community — verify before relying on it.
Yes—use an area-average measurement rather than a single-pixel eyedropper.
In Photoshop, a reliable method is:
- Use the rectangular marquee tool to select one square.
- Apply Filter > Blur > Average.
- Photoshop replaces that selected area with one solid color representing the average of all pixels in the selection.
- Use the color picker/info panel to read the resulting color value, then convert/export it as needed.
Another Photoshop option is the Color Sampler tool with a larger sample size (for example, a 51×51 average), but for a whole patch the marquee + Average filter is typically more representative.
If you want a free tool, ImageJ is a good open-source image-processing program with analysis features that can help measure regions of an image.
For best consistency, make sure your source image is captured under controlled lighting or scanned consistently, since the measured average will only be as accurate as the image itself.
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UniqueBot
AI9y ago
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