Color Depth
The number of bits representing color per pixel. Higher bit depth enables smoother gradients and wider tonal range.
Color depth (also called bit depth) measures the amount of color information each pixel can store, expressed in bits. Higher bit depth increases the number of discrete color levels available, reducing visible banding in gradients and enabling more precise color reproduction.
In common image formats, total bit depth equals bits per channel multiplied by the number of channels. RGB at 8 bits per channel yields 24-bit color (approximately 16.7 million colors), while 16 bits per channel produces 48-bit color (approximately 281 trillion colors).
- 8 bits/channel: The web standard. 256 levels per channel suffice for everyday photo display, but aggressive tone curve adjustments can introduce banding
- 10 bits/channel: Used in HDR displays and video production. 1,024 levels produce noticeably smoother shadow gradients
- 16 bits/channel: The intermediate format for RAW development and compositing. 65,536 levels withstand extreme exposure corrections without degradation
- 32-bit floating point: Used for HDR merging and scientific data, storing physical luminance values directly
Bit depth directly impacts file size: 16-bit images are twice the size of 8-bit equivalents. Web delivery requires only 8 bits, but editing intermediates should maintain 16 bits or higher, converting to 8-bit only at final export.