detecting objects

I have to detect the door,the door is of different colours,please help how to proceed,can we apply colour detection algorithm,if so please tell how to process,struck here dont know how to proceed

Answer 1

[Image Analyst]

See my color segmentation demos: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

I demonstrate 3 different methods.