exif horizontal resolution VS CCD size

[evgeniosc]

What is the meaning of EXIF data "horizontal resolution" and "vertical resolution"?

I own a Powershot G3 and the value of horizontal/vertical is 180 dpi.
I checked theses values in some other compact digital cameras and the value is 72 dpi.

Is this value implies the CCD size?

[PacAce]

No, those values do not imply the CCD size. What they tell you is the resolution that your picture is arbitrarily set to. If you take your image size in pixels (which, for all intents and purposes) equates to the CCD size in pixels, and divide it by this resolution, what you get is the size, in inches, that your image would print at.

For example, the G3 has an image size of 2272 x 1704 pixels. If you were to print a G3 image using the resolution of 180 DPI, the size of the print would be 2272/180=12.6 by 1704/180=9.5, or 12.6" x 9.5".

Since you can change your DPI to whatever you want to suit the print size you need (assuming you don't want to do any resampling of the image), I wouldn't worry too much about what's stored in the EXIFfor the the H and V resolutions.