how can i find the number of bits in an image for calculating compression ratio?

i have to calculate number of bytes in an image but on using size() i am getting CR=1 because size of compressed image and decompressed image is same.how can i calculate CR in this case?

[KALYAN ACHARJYA]

Have you checked, the number of rows and colms in both images (Input image and processed image), if equal you will get CR=1?

[Anu Sri]

they are same....

[Anu Sri]

how can i calculate CR in this case then?