I want to extract/mark/show all blue colors of the image because there are color blinds who see them as black/wrongly. I need to estimate all blue-bluish colors there and be able to change the color group to some other colors if necessary. I cannot change all bluish colors to something else but need to find some compromise. I heard that you can do it by Photoshop (any edition) but I cannot find a way to do it. Map of Paris

enter image description here


1 Answer 1


I have a solution you should try ..

1 - make a layer mask over your photo

2 - double click on the mask

3 - choose color range

4 - pick the first eye dropper ( you also should choose the " image " checkbox )

5 - start to click on the blue spaces which you want to hide or change

6 - you also can choose the second eyedropper ( with + sign ) to add a new color category to the selection

7 - if you accidentally choose a wrong color remove it with the third eyedropper

8 - once you selected all the parts you need just finish the mask and all this parts will be masked

9 - to change the color of this parts you may make a trick to make a new layer below this layer and fill color it whit any color you want ..

i tested it but the image is so blurry :D

i changed the blue parts with white

enter image description here

  • Great! I think this can work. I am going to experiment the quality of your mask in Matlab by the method described here stackoverflow.com/q/29800089/54964 Yes, I agree it is rather blurry. I think the pick is too much. Is there any way about how you can tell me which exact colors you removed. This would help me to see why your work did that and that. - - Another way would be to be able to form a color group based on your image and original image. I think it is possible. graphicdesign.stackexchange.com/q/74252/18754 Jul 3, 2016 at 15:17
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    @Masi actually had you reversed this mask you would have gotten the answer of your other questions.
    – joojaa
    Jul 3, 2016 at 20:22
  • @joojaa You are right. I think output is blue colors then. I think you can do it with ImageMagick. Any proposal? Jul 3, 2016 at 20:42

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