paper size? How is this worked out?

[rustyriley]

can someone please clarify for me how "paper size" is worked out for an image?, like a photograph?
IrfanView suggests the size for one of mine is approx 50"x38" -- kinda big. the image is a jpg taken by a DSLR, approx 1.7Mb in overall fize size (can't remember the resolution) -- I don't think it would look much good at this magnification, but am curious.

Regards all,
Rusty,
New Zealand

[Bhikkhu Pesala]

Print size is based on resolution, or DPI so 50" @ 96 dpi would mean the image is 4800 pixels on the long side. However, if the camera is saving the imagse @ 72 dpi, then there are 3600 pixels on the long side.

The size on disk in Mbytes means very little, as it depends on how much data is compressed.

[MItaly]

A photo taken by a digital camera can't really have a "real" DPI value, since there's no real size-pixels correlation (that instead exists in scanned images). However you can set the DPI settings to the DPI you want to print your image at, so, selecting the "paper size" printing option you will print the image with that quality.