Here is a fellow AVS-er that has done numurous tests between his standard DVD player vs a properly configured HTPC. In his site he has a capture of the same media in a DVD player vs his HTPC.
http://www.myhometheater.homestead.com/HTPC.html
There are many more AVS-er that have done this comparison...including me and we got a better picture using a properly configure HTPC vs a standard DVD using the same projector. A lot of this comparisons can be clearly seen on projectors because we blow up the image to 80-120 inches. You won't see it in standard 20-43 inch TV. In this case size does matter.
HTPC
matching output resolution to projector giving a 1:1 mapping so no scaling occurs. This then uses the technology inherent in software DVD players where hardware technology (chips) and current algorithyms can present the best picture possible. The software is the scaler in this case. Software such as DSCALER, FFDShow and NVDVD are some names that produce these.
DVD player
today there are DVD players that are top notch with built in scalers such as Faroudja or Pixelworks. Players such as the Bravo D2 or the Panasonic RP82. Alas not all DVD players are created equal. Chances are that $50 DVD player you bought mother-inlaw does not have as great as a picture as a properly configured HTPC player or any of the DVD players above.
In reply to:
This really sounds like a Slashdot (oops, /. ) type project. As for HD quality - what is HD quality? You will be sending a 1600x1200 signal to a monitor and beaming a light source through it. Yes, the signal will be a high resolution, but if even professional manufacturers can't get a good contrast ratio on their projectors, I'm not so sure yours will fair very well. You can put a checkmark beside "high res" on your list of cool features, but I'm not so sure how great the final product will be.
Here is a primer on HTDV
http://www.physics.udel.edu/wwwusers/watson/student_projects/scen167/ateam/HDTV/
A few of us actually are ISF calibrate our sets. If not the Avia or Home Theater Essensial DVD can help calibrate your set or projector.
In reply to:
I can scale an NTSC source up to 4,000,000x3,000,000 square pixels, at Sooper-Dooper HD res
So you didn't notice a difference of quality of the same source coming out of your Sooper-Pooper than your mother-in-laws DVD player?
