in Images and Color
InDesign: image scaling issues
InDesign has a lot of features, but a few of them really shouldn't be used when preparing files for commercial printing. Here are two examples:
1. Enlarging images: If your image resolution is 300 PPI, and you place it in InDesign and then use InDesign to scale it up 600%, you've reduced the effective resolution of your original to 50 PPI. It will look jaggy and low-res when output. Don't do that!
2. Reducing line art: If your original has fine lines, like 1/2 point rules or thin lines, if you place an original in InDesign and reduce it to a fraction of its original size (10%-40%), the lines become so fine so as to become unprintable. Don't do that!
For a more thorough discussion of resolution requirements for print, please see our Resource Center article, Understanding image resolution requirements for printing.
The version on the left is high-res and was placed at 100%. The version on the right is high-res, but scaled to 600% in InDesign. It effectively becomes low-res.