DPI explained / vector question

Discussion in 'Design and Graphics' started by Hexiii, May 18, 2014.

  1. Hexiii macrumors 65816

    Hexiii

    Joined:
    Jun 30, 2011
    Location:
    Prague, Czech Republic
    #1
    So I think I know how DPI/PPI works, however I don't get how are vector pictures printed...

    People say you don't have to set PPI when you want to print straight from vector software, but how does it work? How big the image which is 16px in vector size going to be? (Well, I know now, because I tried it, but why?)

    It's about 0.6cm (0.236inch) wide on paper, compared to 16 pixels on screen which means about 68 pixels per inch. (Might be the 72 ppi, it was measured by ruler)

    So how does the scaling work?
     
  2. bit density macrumors 6502

    Joined:
    Mar 5, 2004
    Location:
    Seattle
    #2
    It's a two step process, first the vectors (which are generally output what looks like an interpreted computer program) are converted (The program is "run) to a display list (It becomes a series of trapezoids) in the print device. This process takes into account all of the magic of vectorization. Pixel positions, font hinting, dotted lines, all that good stuff. The display list is then rasterized into a pixel representation (bitmap) of the display list at printer resolution. Usually just enough to support the printing speed of the device. And the final image is printed. Usually this happens on the printer, but can happen on the computer as well (when this happens the computer sends a pre rendered bitmap to the printer). There is also additional information sent that includes things like overprinting, screening size and angles, and trapping information, useful stuff when your final results are going to press. The nice thing about the Adobe products is that they are using PostScript at most stages, so that the rendering on screen will tend to be exactly the same at all the stages, including PDF. This is a pretty simple explanation of a pretty complex process.
     
  3. Hexiii thread starter macrumors 65816

    Hexiii

    Joined:
    Jun 30, 2011
    Location:
    Prague, Czech Republic
    #3
    Oh, thank you, so I am not missing anything, it's just complicated process :) Thanks
     

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