When you place an image in Adobe InDesign, then scale the image, you are in effect altering the resolution of the file. Reducing the image increases the resolution, thus making the file size larger than it needs to be and possibly resulting in a blurry image when printed. Increasing the size of the placed image can result in jaggy images when printed. To quickly check the resolution of your placed, and subsequently scaled, images once they’re in Adobe InDesign, select your image and hit F8 (which will open the Info panel). From there InDesign will inform you of the actual resolution of the placed image, as well as the resulting resolution after you’ve scaled it. As you can see in the screenshot at the right, I placed a 300ppi image into my document and scaled it down by more than half. The resulting image will have an effective resolution of 787ppi when printed – much more resolution than is necessary for offset printing. Not a big deal in most cases, but if you’re placing many large images in your document and scaling them all down really small, your document size is going to be huge, thus making the program run slower and the printed result less than optimal.