Image Arithmetic
Add - Example 2

The examples on this page use the same images as the previous page. All adds are clipped with divisor 2, and illustrate varying bias values. Remember that an add with divisor 2 is equivalent to "average".

Add — divisor 2 bias 40

Add divisor=2 bias=40
Original #1
Original #2
Add — d=2, bias 0
Add — d=2, bias 40

Here we've lightened up the divisor=2 result by using a little positive bias. Since we add 40 to all values and clip them at 255, all values will be in the range 40-255. The darkest colors cannot appear in the result.

Add — divisor 2 bias 80

Add divisor=2 bias=80
Original #1
Original #2
Add — d=2, bias 0
Add — d=2, bias 40
Add — d=2, bias 80

Here we've lightened up the result a little more. All values are now squeezed into the range 80-255.

Add — divisor 2 bias 120

Add divisor=2 bias=80
Original #1
Original #2
Add — d=2, bias 0
Add — d=2, bias 40
Add — d=2, bias 80
Add — d=2, bias 120

At bias=120, All values are now 120-255. Notice how using bias with clip gives you fewer possible colors that can appear in the image. A lot of pixels have reached white (255,255,255).