Old newspapers were printed at 300dpi remember how dotty they were. the average screen has a resolution of 75dpi while quality magazines are printed at 2400 dpi photographs are 2000-4800 or dye sub. So 300dpi will show up as grainy.
When we change the output size of a digital image (without "resembling" or adding pixels) we are only spreading out (or squeezing together) existing pixels. For example: If we have an image that is 3000x2000 pixels and we change its resolution to 1 dpi it will print out at 3000x2000 inches. If we change its resolution to 100 dpi it will be 30x20 inches and at 1000 dpi it will be 3x2 inches. Each image has the exact same number or pixels they are just pushed closer together in some images.
Resembling enables the print to be printed bigger it adds dots to the image “interpolating”
so when printing larger pictures resample them in Photoshop.
Do not confuse DPI with PPI PPI is pixels per inch and usually refers to screen or ccd resolution
hope this helps a little
|