Bit Depth

Submitted by Syv Ritch on 6. May 2009 - 23:00
  1. Bit depth is how many shades you can get between a solid color and no color at all.

An 8-bit image can have up to 256 shades of any color to no color. A 12-bit image can have up to 4096 shades of any color to no color [almost all DSLR support 12 bits data files]. A 14-bit image can have up to 16384 shades of any color to no color [the new batch of prosumers DSLR and the pro-DSLR support 14 bits data files]. A 16-bit image can have up to 32768 shades of any color to no color [the current batch of medium format cameras supports 16 bits data files].

The photo is made of the three primary colours (Red, Blue and Green) that are mixed together to at the number of bits.

There is no relationship between the bit depth and the number of megapixel:

  • The number of megapixel is: the number of cells that the sensor has.
  • The bit depth is: what each cell writes to the data file.

Maximum depth

Various devices allow different rendering of the image.

  1. LCD panel: maximum depth: 8 bit per color = 256 shades per color
  2. Boob-tube/glass monitor: maximum depth: 8 bit per color = 256 shades per color
  3. Ink jet printers: maximum depth: 8 bit per color = 256 shades per color
  4. Dye-sublimation thermal: maximum depth: 8 bit per color = 256 shades per color
  • Since I don't know of any output device that can reproduce more than 8 bit depth, either the output device or the program in front of the output device (such as Photoshop) must downgrade the 12 bit/14 bit or 16 bit to an 8 bit depth.