Wrong selection size when pasting to another picture

[ZenPierre]

Hi,

 

I have two pictures and I try to copy a small part of one picture to the other.

 

I did a rectangular selection of 2 cm square of the first picture and copied it but when I pasted it in the other picture the selection was now 4.68 cm square. 

 

I suspect that's because the two pictures have not the same resolution. 

 

How can I keep the size of the selection from two pictures of different resolution?

 

thanks

 

[pdnnoob]

For this reason, I prefer to work in pixels rather than in centimeters or inches, but I understand there are circumstances where it is necessary to do things another way.

I recommend simply changing the resolution of the second image to match the first. Press ctrl+r and make the appropriate adjustment(s).

The reason I make this suggestion is that raster image editors work in pixels and not centimeters because the image itself is made up of pixels. Changing the resolution while keeping the physical dimensions would change the number of pixels, thereby changing the amount of data contained in the image which can be bad if you are going to a lower resolution, as you would be losing image data that way.