I am just in the planning stage for publishing an e-book. I read this recommendation: "Try to keep the resolution on your images between 96 - 150 DPI. You will also want to keep your image size around 500 x 500 pixels or less." I have several RGB images that I want to include that are much larger than this. I experimented with reducing the size in Photoshop Elements. These are all in landscape mode. All of them could be reduced to about 325 X 500 pixels, but the PPI would be 200. Do I need to find a way to reduce that 200 number closer to 150?