Want to keep the same size (in terms of pixels) but change the DPI (resolution).
For example:
from 1000 x 500 pixels 72 DPI
to 1000 x 500 pixels 300 DPI
Saw some guides that suggested using the image “Resize” tool and the “By Print Size” option.
Never seems to work properly for us. The image just balloons out to something enormous going from 72 DPI to 300 DPI.
Solution
Easiest way for us is to create new image (File > New), using the same dimensions, e.g. 1000 x 500 px. Specify the DPI.
Then copy and paste the other image in. Save. Done.