Some help/advices with background

Hi, I have a question regarding dealing with image background. I created a algorithm which counts amount of fat in meat. It works like that: - Color image - Convert to binary image - Getting H and W values - Getting numbers of black and white pixels in binary image - Then if number of white pixel extends 10% of all pixels in image then print information too much fat else meat is ok. Algorithm works good, but the image has white (or any light) background color which after binarization process is getting white. This distort all the results I got. My question is: what type of image analysis in Matlab I need to perform in order to get rid of white background in color image. The original image http://www.mamopedia.pl/userfiles/A/zdjecia%20dzieciaczkow%20i%20innych%20opcji/wieprzowina-1.jpg Thanks for any kind of help or suggestions.