how to check if detected color is in yellow range?

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The following steps will do this exactly for you

1. Transform your image to a space where color is more easily seperable. I would suggest HSV color space or the YUV color space since you need the yellow range regions.
2. Apply some thresholding on the color channels of the new color space.
3. On the retrieved binary mask you can see which regions are in the desired color band!