When printing pictures via an online service such as Boots or Jessops, is there a particular dpi that I should be aiming for? I recall reading somewhere that 75 dpi was a "magic number", but then I also recall seeing 300 dpi being mentioned as well. I guess my questions are: What kind of printing technology do these online printers use, are we talking dye sub or something else? What dpi do these printers operate at? A related question to this (I guess) is what resolutions would be good for a given print size (eg 6 x 4, 7 x 5, 10 x 8). Please feel free to point me at an appropriate FAQ if there is one. Thanks.