convert pixels to centimeters

[xinyiman]

How do I calculate the ratio between pixels and inches? I managed to create a program that works with pixels, but now my client says I have work to centimeters. How can I do?!

[KpjComp]

There is a screen.pixelsperinch.

But been asked to work in inches for a program your creating sounds like and odd request.

[Blestan]

pixels  / pixels_per_inches  (72 or 96 ) * 2.54 = cm

[marcov]

Pixels what? Pixels on screens, camera images, scanners ?

Note that not all sources (specially cameras!) don't have the same DPI in the X and Y direction.

[ToBr]

Pixels/inch mostly depends on the hardware used.
For a  TV screen you can divide the number of the horizontal lines (e.g. 1080 for HD) by the vertical dimension of the screen in inches.
For a inkyet printer: see the documentation. (up to 1200 dpi).
For a .jpg file to print are required 300 dpi.
The dpi of a .jpg file determines the quality.
Terms Dots and pixels are misused.
Both total number of pixels and pixels per inch are used for quality.
Ask what is required. ppi or total pixels hor and vert
TB

[ToBr]

Pixels what? Pixels on screens, camera images, scanners ?

Note that not all sources (specially cameras!) don't have the same DPI in the X and Y direction.

As far as I know each digital camera has the same dpi in each direction.
The total number of pixels differ, mostly in a ratio of 2:3 or 3:4.
This relates to the dimensions of the printing paper / monitor dimension / old TV screen.
AB