Let us say that I have a 600x600 pixels picture and I want to create a .png file with it that is 6x6 cm in size. What I do is to set the following in "Image->Scale image":
I can check in "Image->Print Size" that my settings seem to be correct, since it tells that the image is 6x6 cm big:
If I export the image as a .pdf file, my pdf viewer (Evince) or other programs (like Inkscape) show it with the appropriate dimensions, namely 6x6 cm. However, if I export it as a .png file, the dimensions change to approximately 17x17 cm. Why does this happen and how can I solve it?
EDIT: the "Export As" options that I use are the default ones, where the "Save resolution" box is checked.