How should I preform the feature extraction for a logo image?

I have 2 logo images, from them one logo is a fake logo and another is a real logo. The fake logo has a dark color backgroung but the real logo doesn't and now i need to do fearture extraction on these images but I do't know which mehod is best for this perpose. I need to extract a numberic value from these images.

Please someone guide me what should I do.

Real logos:

Fake logos:

[hamida]

Image Analyst, Sir do you have any idea about it?