3 ms·

DPI is very different though, a screen sub pixel can vary in luminescence (typically index in most displays with 6bits of accuracy, minus crappy colour gamut on

DPI is very different though, a screen sub pixel can vary in luminescence (typically index in most displays with 6bits of accuracy, minus crappy colour gamut on the display) whereas a printed dot is limited to the ink colours used. Some printers overlap dots, print thicker dots, and have other tricks to work around this aspect. I don't know as much about this area, I've worked mostly in graphics, but my understanding is that because the colour gamut for each printed 'pixel' is less expressive, you need more dots in the same area to get a similar result. Furthermore, dpi expresses printed 'dots' whereas a pixel on most displays can be considered three fixed 'dots', one for each display channel. Although lately, some LCD substrates are cheating a little and displaying only 2 subchannels per pixel. Anyways, that's everything I know about dpi, as I said, I'm more versed in video rather than printing. So take this with a grain of salt: I think you need to multiply PPI by 3 to get DPI, ignoring cleverness on the part of either display or printer manufacturers.

bane 14y ago
That's basically right in some cases. For example in full-color (4 color) printing you essentially need 4 dots (halftones) to make any color. However, they aren't all necessarily lined up in a grid like pixels (it's an analogue medium). But simply dividing 1200 dpi by 4 doesn't really provide a correct calculation for the resolution at the end. http://blog.savvydog.com/?p=106 http://blog.savvydog.com/?p=106 And then you actually get into measuring with LPI (lines per inch) which can easily go above 300 for things like good magazines (though around 130-150 is more typical). 130-150 is actually around the retina display's 300dpi (a good conversion estimate is that 1LPI=2DPI but some will go as high as 3DPI). Black and white (non-process) printing can be very different and uses solid colors. Higher quality artwork is necessary for this. That's where the 1200dpi comes into play. Fine books, black and white artwork, etc. need artwork at 1200dpi and the LPI can easily go above 500.

bane 14y ago

That's basically right in some cases. For example in full-color (4 color) printing you essentially need 4 dots (halftones) to make any color. However, they aren't all necessarily lined up in a grid like pixels (it's an analogue medium). But simply dividing 1200 dpi by 4 doesn't really provide a correct calculation for the resolution at the end. http://blog.savvydog.com/?p=106 http://blog.savvydog.com/?p=106 And then you actually get into measuring with LPI (lines per inch) which can easily go above 300 for things like good magazines (though around 130-150 is more typical). 130-150 is actually around the retina display's 300dpi (a good conversion estimate is that 1LPI=2DPI but some will go as high as 3DPI). Black and white (non-process) printing can be very different and uses solid colors. Higher quality artwork is necessary for this. That's where the 1200dpi comes into play. Fine books, black and white artwork, etc. need artwork at 1200dpi and the LPI can easily go above 500.