what is common between objects of nearly same colour?

sir, suppose a common man observes a object and predicts about the color of the object as it is near to true color(say red) . i am eager to know what is the thing that make him able to decide that it is near to red. so , what is common between the objects of nearly same color but some different .....as i know that the rgb values will be different ...then on what color scheme we can predict the common properties about the color of the object.....please reply soon..

[satnam singh]

ANY ONE THERE HAVING THE ANSWER.....PLEASE REPLY SOON...

[Walter Roberson]

That does not appear to be a MATLAB question; it appears to be a question about the properties of the human visual system.

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colper.html

[satnam singh]

sorry sir for making the question in wrong direction,,,what i am asking is ,while writing the program,,,suppose an object is red looking but not true red...then what logic we can implement to say that it looks like red????

Answer 1

[Image Analyst]

Delta E is the "color difference" and is basically the distance between two colors plotted in CIE LAB color space. I have a demo in my File Exchange where you can outline a colored region and then specify a Delta E, and it will find all colors in the image that are closer than your specified Delta E to the mean color of the region you drew. Please download it and run it.

http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

[Image Analyst]

satnam, what's the latest update?

Answer 2

[Jan]

As long as you cannot define "true read" exactly, it is not meaningful to ask for the distance between a color and "true red".

Usually "similar" colors are processed in e.g. the HSV parameterization instead of RGB. Then the first component Hue is separated from the Saturation and the Lightness. But to apply this, you have to define at first that the similarity of colors means the distance in the Hue component. But this might be a question of taste and it might be helpful for astro physicists for the determination of colors of starts, but a horrible idea for designers, who never would combine light red socks with a dark red pair of trousers.

Therefore I agree with Walter: The actual problem is, that you have to define, how you would measure if colors are "near" to each other. There cannot be a general answer and this is not a problem of Matlab.