Calculating Montiors DPI

bobert50 · 13 Apr 2007 at 15:12

I feel a bit daft for asking! but how do you work this out?

I've come across a program with a quick search and found

http://www.raydreams.com/prog/dpi.aspx

But when i put something in as an example it reads such as:

DPI = 64

rather than say..0.303 or whatever.

Where am i going wrong?

drak3 · 13 Apr 2007 at 15:34

64 dots per inch.

.xxx is the distance from dot to dot

Vertigo · 13 Apr 2007 at 15:47

Fairly basic maths tbh.

First find the aspect ratio of the screen by dividing the horizontal res by the vertical. This gives 1.6 for widescreen units, 1.333 for most non-widescreens and 1.25 for the oddball 1280x1024 resolution 17" and 19" units.

Now take the inverse tangent of this value to find the angle of the diagonal from the vertical, so 1.6 gives 58 degrees, 1.333 gives 53.1 deg and 1.25 gives 51.3 deg.

Now take the sine of this angle to give the ratio of the horizontal width to the diagonal length, so for a widescreen unit this is 0.848. Multiplying this by the diagonal length, such as 22 inches, gives the width in inches of 18.66. Divide this into the horizontal res, such as 1680, to give the DPI which is 90.

The other figure is the dot pitch, usually expressed in mm. To get this, divide the DPI into 25.4, which with 90 gives .282mm pitch

HTH

bobert50 · 13 Apr 2007 at 18:06

Thanks!

all sorted!