Image DPI and Scaling, and Resultant File Sizes: Difference between revisions
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Here we see why you get that warning when image resolution | Here we see why you get that warning when image resolution is below 150 DPI, but recall that this is a high magnification in Adobe Reader, so this pixelization could be quite acceptable for a PDF made for the web. |
Revision as of 03:05, 20 October 2010
This article will show the results of some experimentation with modifying the scaling of images, and how this will affect PDF file size. The results are likely to surprise you, since first of all, this is not simply a matter of adjusting the scaling of the image in Properties > Image, since you can also set limits on the DPI and image quality at the moment you export to PDF.
Adjusting the Image File
Here is the simple Scribus document we will work with, a single US letter page with one image frame, and the entire image adjusted to frame size.
But What's the Cost?
Now we'll load these 3 PDFs into Adobe Reader, view at 400% magnification, then capture a detail where we can see some sharp contours and big color changes.
553.5 DPI | 276.7 DPI | 138.4 DPI |
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Here we see why you get that warning when image resolution is below 150 DPI, but recall that this is a high magnification in Adobe Reader, so this pixelization could be quite acceptable for a PDF made for the web.