As noted in my sketchbook, I had a lot of issues with my photographs: they were taken at 72DPI. So I had to try to bring them up to 300DPI, but this was proving confusing and difficult as I knew not to resample the images when trying to change the resolution, but the dimensions and DPI would change when you changed the other.
See sketchbook for my notes on how I remedied this:
I did try to make the process less time-consuming, and I looked up how to create a batch on photoshop. However, it then saved the images in jpg format rather than tiff which is what was preferred, so I did them individually. I couldn’t find an option to change their file-types on the batch screen.