# bits/pixel

Discussion in 'General Electronics Chat' started by tojeena, Jul 1, 2013.

1. ### tojeena Thread Starter Active Member

May 2, 2009
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In one paper i read giving values bits/pixel in the range 0.25-2.?what does it mean?will it affect the psnr?psnr is dependent upon B,dynamic range,does bits/pixel(rate) has any relation with dynamic range also?

2. ### donpetru AAC Fanatic!

Nov 14, 2008
185
27
The number of distinct colors that can be represented by a pixel depends on the number of bits per pixel. A 1 bpp image uses 1-bit for each pixel, so each pixel can be either on or off. Each additional bit doubles the number of colors available, so a 2 bpp image can have 4 colors, and a 3 bpp image can have 8 colors:

• 1 bpp, 2^1 = 2 colors
• 2 bpp, 2^2 = 4 colors
• 3 bpp, 2^3 = 8 colors....
Peak Signal to Noise Ratio (PSNR) is the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation.
For example,

PSNR = 10 * log10 (M^2/Ms);

where: M is the maximum possible pixel value of the image (if you using 8 bits per sample, M is 255); Ms is mean squared error (MSE).

3. ### tojeena Thread Starter Active Member

May 2, 2009
118
0
what about the gray scale image ?in the particular paper they have given bpp from 0.5 -2 range? so psnr doesnt depend on bpp?

4. ### donpetru AAC Fanatic!

Nov 14, 2008
185
27
Look at mathematical formula that defines PSNR. In the mathematical formula there is a term denoted by "M" which, according to its definition, is directly proportional to bpp. So, we can say that: PSNR depend on bpp.

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5. ### tojeena Thread Starter Active Member

May 2, 2009
118
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thank u for the reply.what does it mean to give manually bits/pixel or compression rate from 0.25 to 2