UGC NET CSE | June 2012 | Part 3 | Question: 10

Question

In an image compression system 16384 bits are used to represent 256 $\times$ 256 image with 256 gray levels. What is the compression ratio for this system?

• A. 1
• B. 2
• C. 4
• D. 8

Comments

compression ratio = (256 * 256 * 8) / (16384) = 32

Answer 1

$\frac{256 \times 256 \times 8}{16384} = 32.$

Comments

will 256(8 bits) gray levels has no effect

should it not been 256x256x8 /16384 =32

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yes, it should be 32..

Answer 2

For gray levels, a pixel can be represented by 8 bits. Total bits for this image is 256*256*8. so the compression ratio will be 256*256*8/16384 =32. 32 option is not here. For photographic images, Compression Ratio is usually below 2 for lossless, but can reach over 10 for lossy compression. 

The option (b) may be the right option. I am not sure.