How to resize an image on the computer?

I have an idea as how to measure inches and pixels but I don't know about the printer, sorry... I'm only writing all this just in case it helps. (Probably no, but who knows)

Try this:

- Open an image editor (photoshop, paint shop pro, gimp, whatever)

- Press File > New (new image)

- Select the dimensions of the new image. Select them based on inches. Make sure to write the original inches you actually want (3x2.5)

- Press "Ok"

- A new canvas will appear

- We don't care about this canvas. Ignore it. We just wanted to point out, to be sure, that the next time that you will press "New image" the "New" menu will appear with the dimensions you already wrote before, as the default dimensions for the next new image, since the program keeps the last record as an option for the next new image

- Now, open again the "New image" menu and instead of "inches" choose "pixels" WITHOUT changing the the "3x2.5" you wrote before

- Press "ok". This new canvas has EXACTLY the same pixels as inches and viceversa.

Hope that helped :)

PS: If I'm right, printers have some options called:

- Actual size

- Scale 100%. And a check box near by, with the "Shrink to fit page width" option

This "Shrink to fit page width" is a very useful option if you know the dimensions -inches or pixels doesn't matter since you can calculate them with them above trick - of a A4 page ...

Try to use this picture resizing tool

http://www.softorbits.com/batch_picture_resize/

It works well!