: I think it is customary practice for printers to "demand" image files at 300 dpi (whatever : that is) at final printed size of a reproduction. I guess this is to reproduce images so : they have a high quality and don't look pixelated or something. (I think I have : oversimplified things). : : In any case, I was pondering whether one can get a fair idea of whether an image file has : sufficient digital "resolution" so that when printed it will look "good" by looking at the : image at a larger size than what it will be reproduced at. So if I have a 5x5 cm image : file at 300 dpi but I look at it on my CRT or LCD screen at 200% or 300% or 600% or more : magnification and at 300% the image on my screen looks OK ... but at 600% it starts to : fall apart ... is that an indication of anything? : : Hope I have not been to obfuscating in this question ... drinking a Snapple only. : : cheers, : andy he means he wants the image to have an allocated 300 pixels per inch ..ppi, not dpi (a common mistake) so - if *you* want a 10 inch x X inch image then there must be (300x10) 3000 pixels x Y pixels As to how this will look on your screen, that depends on your screen resolution and as has been said, the program you look at it with. If you were to drop the image into your browser and it'll appear at your screen resolution An example: say you have something like my setup - a screen that is 17 1/4 inches wide x X high your screen resolution set to 1600 x 1200 (forget the 1200) I have a TOTAL of 1600 pixels across the 17 1/4 inch width of the screen, so that is 1600 divided by 17.25 = 92.75 my monitor resolution is 92.75 Back to the example - my image for printing is 3000 pixels wide, my monitor is diplaying this image at 92.75 pixels per inch, so the image will be 32.3 inches wide on my monitor - or roughly 1.8 times wider than my screen. let's say I had my monitor set differently, say a lowly 800 x 600 now I have a total of only 800 pixels spread across the whole width of my 17.25 inch wide screen - my screen resolution is a very lowly 46 pixels per inch! Now this 3000 pixel image wide image will be roughly 64 inches wide - or almost FOUR times as wide as my monitor no surprise, at 1600 pixels (twice the lower 800 pixel res) the image is only half as big ;) As to how big (filesize) this will be depends on the format and compression it's saved with AND what detail the image has . An example I take a randomly selected 754x834 cluttered image and save it as a BMP, TIF and JPG they are respectively in size: BMP - 1,844 kb TIF - 1,770 kb (LZW compression) JPG - 220 kb (100% quality) Next I take a pure black image, same size and save it exactly the same as above, the file sizes are now: BMP - 1,844 kb TIF - 39 kb (LZW compression) JPG - 5kb Obviously some compression is advantageous when trying to minimize wasted space when there's redundant data in the imes (ie, lots of blocks of the same colour! ;)
