Pixel Color from Camera Feed [closed]

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When using a camera in gazebo is there a good way to process pixel data from the feed seen with image_view?

rosrun image_view image_view image:=/camera/image_raw

I'm trying to implement color detection from the camera feed to find objects, or blobs of a solid color. I haven't seen where this would actually give pixel data from the feed though... any information would be much appreciated.