I have images that I made 1:1 in one Photoshop document. I then am dragging and dropping them (either as the whole image or cropped regions) into another Photoshop document (both documents are 1000 ppi), but Photoshop is doubling the size of the image on transfer (i.e. the image goes from 1'x1' to 2'x2' in the new document). How do I stop this? This is only happening with some of my images. Images that I scanned and then opened in Photoshop, seem to be fine, but images that I exported from another program and then saved as Photoshop documents are affected. I'm using CS 5.
It really look like a resolution issue but if the resolution is really the same...
Some things you can verify:
1) Do your images have the same numbers of bits (8-16-32)? Verify this in "mode" in the "image" menu.
2) Have a look at the "View" menu for any "pixel ratio correction" and reset it to "square" if you want the default one.
3) Have a look at the "variables" in "image" menu; you should uncheck "pixel replacement" if it's checked.
4) I don't think this option was available back in CS5, but you can look in your preferences panel for any "resizing" when you place images. Maybe you'll find another option in the preferences that creates the resizing you're describing.
5) When you say you "transfer" the images in the new document... you should open them first in Photoshop, verify the points above, and resave these images, eg. don't place directly the other image from another software directly in your main document.