Compression Ratio???????

Question

How many bits would be needed for one image if a JPEG (700 x 250 pixels) applies a compression ratio of 35:1?

Answer 1

The initial math says the effective pixel number would be 700 * 250 / 35 = 5000. To figure the number of bits you need to know how many bits per pixel are used for the color attribute. Apparently jpg files always allocate 24 bits for color (see ref.) So you get 120,000 bits or 15,000 bytes for the image. Add a little more for the jpg header, which is pretty small.