Mouse dpi
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[edit] DPI and its use
DPI stands for Dots Per Inch and is most commonly used in measuring the resolution of a printer or scanner. DPI in mice is somewhat different.
To understand DPI in mice, the following calculation can be applied: Vertical lines multiplied by the Horizontal lines divided by the screen size and finally divided by the DPI of the mouse. If given a screen size of 20" in a resolution of 800 x 600 and a mouse with a high DPI of 2000 is used, this would give us the calculation 800 x 600 / 20 / 2000 which spread out with answers is this 800 x 600 = 480000. 480000 / 20 = 24000. This means that on screen there are 24000 pixels per every square inch and because DPI is another name for PPI (pixels per inch) its fair to make this calculation. 24000 / 2000 = 12. The final answer is the number of pixels you have to physically move your mouse to move the cursor 1 pixel on the screen. With another calculation, it is simply to see the effect of DPI, resolution and screen size have on how the cursor reacts to movement of mouse. For example, changing a screen size to 18" 800 x 600 / 18 / 2000 = 13 (rounded up). The factor of size is not normally deemed a problem as the difference is very minimal, but it still affects it. However, DPI has a much greater effect on the outcome 800 x 600 / 20 / 1000 = 24 which is as you would expect twice the movement needed due to being only half of the DPI which in turn means that you need to move the mouse twice as far for the same effect. Changing resolution to a higher one requires that you have a higher DPI to still only move 1 pixel per every 12 actual movements 2000 x 1500 / 20 / 2000 = 75 actual movement which means you would have to have an insanely high DPI of 12500 compared to if you was in 800 x 600. This is where mouse sensitivity comes into it because at such high resolutions people don't want to move the mouse 2000 x 75 = 150000 actual pixel movement so they have higher sensitivity which is all that it is that it no longer requires that amount of pixel movement but considerably less. Also there is Mouse acceleration which automatically speed up the cursor movement depending on how far it has to go this is also a great help and provides a much needed service in the operation of real movement to movement.
