Separating and stacking RGB images

I have a body of 3 images contained within 1 file. In descending order they are Blue > Green > Red channels, so that when combined they will produce a full RGB image. I require a method of splitting the images into 3 seperate files using an automated method. I have managed to manually select the x,y co-ordinates to succesfully remove them from each other but were this to be applied to more than 1 image it would be a time consuming process and as such require a method that will automatically find the edges (using Sobel or prewitt preferably).

Any help greatly appreciated

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers