I recently read [jrista's][jr] **marvellous [q&a][1]** from [photo.stackexchange](http://photo.stackexchange.com/).

While the question is titled [***"How do I generate high quality prints with an ink jet printer?"***][1] it covers DPI & PPI relationship to quite an extent and has real-world print examples.

Current Q&A contents:

- [Summary][2]
- [Detailed Explanation][3]
- Empirical Studies: 
    - [Does PPI really matter?][4]
    - [Extreme digital upscaling][5]

[1]: http://photo.stackexchange.com/q/1715/1913 (How do I generate high quality prints with an ink jet printer?)
[2]: http://photo.stackexchange.com/questions/1715/how-do-i-generate-high-quality-prints-with-an-ink-jet-printer/1723#1723
[3]: http://photo.stackexchange.com/questions/1715/how-do-i-generate-high-quality-prints-with-an-ink-jet-printer/1716#1716
[4]: http://photo.stackexchange.com/questions/1715/how-do-i-generate-high-quality-prints-with-an-ink-jet-printer/2737#2737
[5]: http://photo.stackexchange.com/questions/1715/how-do-i-generate-high-quality-prints-with-an-ink-jet-printer/3985#3985
[jr]: http://photo.stackexchange.com/users/124/jrista