MATLAB: Red object detection picking up yellow color.

color detectionimage processingMATLABred color

Part of my program isolates the red objects in an image and displays them in a binary image. It works well but has been including yellow objects which is an issue. I've tried adjusting the values in my code with no luck.
img = imread(imname);
gimg = rgb2gray(img);
red = imsubtract(img(:,:,1), gimg);
red = medfilt2(red, [4 4]);
red = im2bw(red, 0.15);
redObjects = bwareaopen(red, 200);
The red objects in my image are all exactly [1 0 0]. Is there a way to do this with hsv that might be more accurate or am I missing something simple here?

Best Answer

You extracted ONLY the red channel. Then you looked for red colors. But there are other colors which have the red channel maxxed out, yet are not red. Color is THREE dimensional. If you ignore the other two channels, expect to fail at your task. Your methodology would have found the [1 1 0] color too, calling it "red".
If your goal is to find ONLY colors which are explicitly and exactly [1 0 0], then use tools that can do so.
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