What is Bit Depth? How does bit depth and file size relate?
A bit is a binary digit, which can only have a value of 0 or 1. The colour of each pixel is stored in just 1 bit of space in the computer. Bit depth is the number of bits in each pixel. Color depth is the maximum number of colors in an image and is based on the bit depth of the image and of the displaying monitor.
Color Resolution (color depth) is the number of bits of data used to store information about the color of each pixel in an image. This is also known as bit depth or color depth. The higher the color resolution, the greater range of possible colors in the image, and the larger the file size. Typical color resolutions are 8-bit, 16-bit, or 32-bit, although others are possible.
Bit depth defines the number of colours available to each pixel within an image:
BitDepth Colours Available 1-bit black and white 2-bit 4 colours 4-bit 16 colours 8-bit 256 colours 8-bit greyscale 256 shades of grey 16-bit 32768 colours 24-bit 16.7 million colours 32-bit 16.7 million + 256 Levels of transparency
8-bit image = 256 colours With an 8-bit image, each pixel can be one of 256 colours.
24-bit image = 16 million colours With a 24 bit image, you have 16 million colours, made up from 256 shades of red, 256 shades of green and 256 shades of blue.
All the colours are made up from varying amounts of these primary colours, so for example, 0,0,0 would be black and 255,255,255 would be white. 255,0,0 is red. 0,255,0 is green and 0,0,255 is blue, 255,255,0 is yellow, 255,0,255 is magenta and 0,255,255 is cyan.
Each value of 0 - 255 takes up 8 bits, so the total amount of space to define the colour of each pixel is 24 bits.