Please explain DPI

Discussion in 'Beyond the Basics' started by Pirate, Dec 26, 2006.

  1. Pirate

    Pirate TPF Noob!

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    In looking for a new photo dedicated printer I'm getting confused with the dpi thing. I mean I'm not stupid, and I know that the better the dpi on the camera means more vivid, more detailed, well just plain a better photo. However (and here is my confusion) the printer that I am looking at is 9600x2400dpi. Ok so that's good, and I realize that photos with film is printed just around 300dpi. But the better and more expensive Epsons the dpi varies, but is significantly lower than the 9600x2400. I guess that my question is simply how do lower dpi printers print better photos. And I consider Epson the standard.
     
  2. markc

    markc TPF Noob!

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    This is a pretty good article on the subject: http://www.rideau-info.com/genealogy/digital/dpi.html

    It should also be noted that some labs have printers that require 300dpi prints because of they way they are set up. That's only certain kinds, but so many shops have still taken up this mantra before understanding it. Most modern inkjets don't, and I haven't seen a modern consumer printer that does.
     
  3. Alex_B

    Alex_B No longer a newbie, moving up!

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    all three wrong ;)

    dpi on the camera means nothing, what counts is the number of pixels (pixels x pixels). (There are ppi though, which refers to pixels per inch on a sensor or on a scanner, but that again does not tell you anything unless we also talk about the format of the film scanned or the size of the sensor.).

    and even this does not give more vivid images, it does mean higher (pixel-)resolution, which together with good lenses means higher overall resolution.

    as for "plain better photos" .. those require much more than resolution as most in here won't argue ;) .. but that is a different story alltogether ;)

    [EDIT: Removed some untrue statement here!]

    That is a very antique and outdated consideration to my knowledge ...
     
  4. Alex_B

    Alex_B No longer a newbie, moving up!

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    or maybe i missed recent adavantages in printing ... but then still that resolution is useless ;)
     
  5. markc

    markc TPF Noob!

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    I haven't noticed them that high yet, but the Epson 2400 is 5760 x 1440dpi. DPI, not total. Another aspect to consider with printer DPI (as opposed to image PPI), is color blending. A DPI higher than the image resolution may not give more actual detail, but it will allow more dots to be printed to assist with smooth color blending. It allows the printer to hide any halftone or dither pattern it may have to use to make the color of the pixel given it's limit of 6 inks, which is one reason why the modern inkjet is so great at making photo prints compare to older ones.
     
  6. Alex_B

    Alex_B No longer a newbie, moving up!

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    hmm, ok , so i take back my statement ... I have to admit I had not an eye on the printer market for a couple of years.

    colour blending is certainly an issue where the dpi help
     
  7. markc

    markc TPF Noob!

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    I guess I skipped this part. Having a high DPI is important, but not everything. Once you get to a certain point, it becomes a marketing tool. The number of inks and their quality have a big impact. 6-inks certainly beat 4 for realistic color. Some of the new color combinations are interesting, and having one or more greys in the the inkset help a lot with B&W prints. Some of the new ones have green or red. The construction of the print head will also matter. The archivability of the inks is something else to consider. I seem to remember that when Canon first started with their inkjets, the prints would have noticeable fade after only a month. They've certainly improved things by this time, but it's something to look at when choosing a printer. The longer lasting inks tend to be pigment based instead of dyes.
     

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