how to get number of pixels of red color in an image??

i am taking an image through web cam, how to recognize how many pixels are there for specific colour such as red

Answer 1

[Walter Roberson]

The first step is to rigorously define "red". By the time you have finished doing that, you will be due to retire.

Answer 2

[Image Analyst]

swapna, please check out my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862. I show several ways to segment out pixels of certain colors. You can adapt the code to select as narrow or as wide a range of colors as you want. Also check out the general File Exchange. It seems that tracking colored objects (balls, lasers, etc.) must be one of the most common student projects.

[Medical Imaging]

Dear sir I have one ground truth image(image 1) and other segmented image(image 2). I want to compute the number of pixel for white area for image 1 and number of pixel for red area in image 2. and then want to compute the difference of pixels.

[Walter Roberson]

In this situation, for each of the images, you can just calculate

nnz(TheImage(:,:,1))