Re: photoshop and dpi



When you raster up (or res-up) an image that was originally scanned at a low resolution, the new pixels or dots that make up the new, higher resolution image are invented by the program that you are using to raster up, still leaving the image with an appearance of jagged edges. Always, before sending a desktop publishing document such as QuarkXpress, Pagemaker, etc., out for film and print, be sure that you check with the printer to find out what dpi their imagesetter outputs film. Most imagesetters output at 2400dpi. To get the best possible quality of your scans, always scan at the optical resolution of your scanner, then in your image editing program resize the image down to 300dpi with whatever height and width it will appear in the final document. Do this before imorting the image to another program for page layout. Notice I said resize the image down, that's because most scanners have an optical resolution of no less than 600 to 1200dpi to start with. If your 300dpi image is larger than the imagesetter can use, it will not be by much and the final output will be as crisp as it can be within the printers limitations. You can also ask your printer what resolution your final image sizes should be saved for optimum results on their equipment. -Steve Morris