Bith Depth

The ‘bit depth’ of an image is how many colours can be used. these can range from 1-bit to more than 24-bit “true colour” images. The bit depth of an image is measured in Pixels Per Inch (ppi). This measurement can vary depending on the resolution of the monitor on which it is displayed.

In our everyday life, we deal with numbers that can be broken down into standard form. fpr example, 65,231 can be broken into (6 x 10^4) + (5 x 10^3) + (2 x 10^2) + (3 x 10) + (1 x 10^1). To make it simple, 60000 + 5000 + 200 + 30 + 1. The 10 digits (0-9) we use are known as ‘base 10′ and on a computer are the ‘two fingers’. however, on a computer a base 2 system is used with only the numbers 1 and 0. Either 1 or 0 is always followed by a power of 2.

1001011 = (1 x 2^6) + (0 x 2^5) + (0 x 2^4) + (1 x 2^3) + (0 x 2^2) + (1 x 2^1) + (1 x 2^0)

1001011 = (1 x 64) + (0 x 32) + (0 x 16) + (1 x 8 ) + (0 x 4) + (1 x 2) + (1 x 1)

1001011 = 64 + 8 + 2 + 1

1001011 = 75

This system of base 2 makes it much easier to work with colour values. This is known as Binary. The Hexadecimal system uses a base 16. This means that a number is followed by a power of 16. As 16 is 2^4, one digit in Hexadecimal represents 4 Binary digits. However as there are only 10 digits, the letters A to F are used to represent other numbers; A = 10, F = 15. The base number is the bit depth of the image. Base 16 is 16-bit, base 32 is 32-bit, etc.

B2A1 = (11 x 16^3) + (2 x 16^2) + (10 x 16^1) + (1 x 16^0)

B2A1 = (11 x 4069) + (2 x 256) + (10 x 16) + (1 x 1)

B2A1 = 44759 + 512 + 160 + 1

B2A1 = 45432

These numbers are used as the Hexadecimal number when picking a colour, say for example, a website.

~ by Fizwidget on November 15, 2007.