TIP: Changing DPI of many files at once (Windows needed)
I found great app for Windows, it's free and it can change DPI of many images at once - FastStone Photo Resizer.
http://www.faststone.org/FSResizerDownload.htm
Just choose your images folder and drag it to the upper right window, than choose output folder, output format and click on Advanced Options, there go to DPI tab, click on change DPI and choose 72 in X-DPI and Y-DPI, then click ok, and Convert. After few minutes (depending on graphics amount - for me (almost 1000 graphics) it took 2.30 min) you will get all your graphics with 72 dpi.
Great tool!
http://www.faststone.org/FSResizerDownload.htm
Just choose your images folder and drag it to the upper right window, than choose output folder, output format and click on Advanced Options, there go to DPI tab, click on change DPI and choose 72 in X-DPI and Y-DPI, then click ok, and Convert. After few minutes (depending on graphics amount - for me (almost 1000 graphics) it took 2.30 min) you will get all your graphics with 72 dpi.
Great tool!