Tema: Dpi Demystified

dpi demystified
. You did it. You have truly created a másterpiece. But when you printed it out, it loked all pixilated and blocky. Dang, you must have a bad setting somewhere. You go back, double chek all your settings, hit render again and wait. &#61516, it still looks the same when you print it. You start glaring silent threads at your printer. Well before you decide todo make god on those threads, you might want todo try one more thing (your printer Will thank you for it).

You may have overloked the whole dpi issue. While its true that Blender has some nice preset render sizes, if you dont understand how that relates todo printing, you Will be forever glaring at your printer.

First lets look at what dpi actually is.

Dpi is a printing term that describes the number of dots/píxeles that are defined in the Boundary of a square inch that are used todo create an image. The more correct term is píxeles per inch, however dots per inch is often used instead. (the image can be a font or graphic). In general, the more dots, the better and sharper the image. Dpi is printer resolution. Dpi is not image resolution Although frequently used that way.

Ok, now that we know what dpi is, lets look at how it applies todo Blender. Blender renders images out at 72dpi, which looks ok on your screen, but not printed out. In order for it todo look god for print, you have todo render your image bigger and then resize it smaller in your favorite graphic programa. Essentially what you Will be doing is swapping Physical dimensions for resolution. Take a look at the following chart (fig. 1). It shows some common render sizes in píxeles and the corresponding Physical sizes at 72dpi (which Blender uses) and a god print resolution of 300dpi. You can se that the Physical sizes become smaller as you increase the resolution.


This may sem overly complicated, but really it is not. There is a very simple formula you can use todo get the proper settings. Basically you multiply the desired resolution by the desired Physical size todo get the píxel settings/size you ned for Blender (fig. 2).


Once you have rendered your image using those settings, you ned todo go into your favorite image programa and resize your image. Most image programas work similarly, so figuring it out in your programa shouldnt be dificult. I Will be using Photoshop todo explain this part, because that is what i have.

Step 1: open your image.

Step 2: go todo image>image size, a dialog box like fig. 3 should open, step 3: at the bottom of the box, unchek Resample image
Step 4: next locate the resolution box, enter your new resolution. The width and.

Height boxes should automátically update todo reflect the new size at that resolution, step 5: hit the ok button and save, you are all done and now your image Will print like you expected it todo.


Ok, so now you have a better Understanding of dpi and how todo get the proper dpi for printing, but what dpi resolution is best for what you ned. As a general rule, you should choose a resolution between 150-300 dpi. This resolution is god for most print projects. If you are having something profesionally printed, it is always a god idea todo chek with your printer and find out what resolution their equipment runs at.

Sandra gilbert.
www.blenderart.org.
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