CODEWITHSUNDEEP
imageimage-processing
Mubeen Javed
Mubeen Javed

Reputation: 43

What does bit per color channel means?

Determine the number of bytes necessary to store an uncompressed RGB color image of size 640 × 480 pixels using 8, 10, 12, and 14 bits per color channel? I know how to calculate the size of image by using Size = (rows * columns * bpp) but i cannot understand what bit per color channel means in this question

Upvotes: 3

Views: 5592

Answers (1)

Rotem
Rotem

Reputation: 32084

Bits per color channel, is the number of bits that are used for storing a color component of a single pixel.

RGB color space has 3 channels: Red, Green and Blue.
The "bits per color channel" (bpc) is the number of bits that are used for storing each component (e.g 8 bits for red, 8 bits for green, 8 bits for blue).

The dynamic range of 8 bits is [0, 255] (255 = 2^8-1).
8 bpc applies 24 bits per pixel (bpp).
The number of bits per pixel defines the Color Depth of the image.
24 bpp can represent 2^24 = 16,777,216 different colors.

More bits applies larger range: 12 bits range is [0, 4095] (4095 = 2^12-1), and much larger colors variety can be coded in each pixel.
12 bpc applies 36 bpp, and can represent 2^36 = 68,719,476,736 different colors.

For more information refer to BIT DEPTH TUTORIAL

Remark: The bits per channel is not directly related to memory storage (e.g. it's common to store 12 bit in 2 bytes [16 bits] in memory).

As you probably know, an image is built as a matrix of pixels.
Following figure illustrates the structure of an RGB image:
RGB image

Following figure illustrates a pixel with 8 bits per color channel:
8 bits per color channel

Following figure illustrates a pixel with 10 bits per color channel:
10 bits per color channel

Following figure illustrates a pixel with 12 bits per color channel:
10 bits per color channel

There subject is much wider than that, but I think that's enough...

Upvotes: 6

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