MPC render video differently while in different DPI?

[Chengbin]

I have a HTPC, and I hooked it up to a 1080p TV. For months I'm thinking why does cable HD look better (detailed) than Blu ray. Then today I found the answer.

I turned up the DPI for text in Windows 7 to 150% bigger than before. This somehow affects video rendering. Here are 2 comparison pictures.

High DPI (enlarged text size)

http://img683.imageshack.us/img683/1334/highdpi.png

Low DPI (normal text size)

http://img148.imageshack.us/img148/4792/lowdpi.png

Look at the fine details on the person's face. Notice there is a lot more detail on the Low DPI screenshot. There is one part that troubles me. Look at the hair of the person on the right. The color is different as well. Why does this happen? Is there any way to have large text and correct video output?

Thanks.