Blu-ray versus DVD - Why do we never see a comparison?
The problem with any comparisons between resolution from Blu-ray and regular DVD is that people look at many different aspects of the image to decide if it is clear or sharp. We see light intensity and patterns much more accurately than color. I think that TV manufactures are reluctant to publish comparisons because selling HD TV's happens best when the customer comes in and looks at the product, not by math and charts.
Many people dismiss blu-ray as not that much of an upgrade. This comparison will show that they are wrong!
Blu-ray versus HDTV
Blu-ray compared to broadcast HDTV cable, satellite or over the air (OTA) broadcast is another issue. Blu-ray is still better than all Broadcast HD which compresses the image more than blu-ray. Blu-ray comparisons to cable HD and OTA is not covered in this study.
Basis of this study
This study is based on principles of acceptable focus in still photography. Photographic and cinemagraphic lenses are made with depth of field values (what is sharp). If you hold a photograph 10 inches away most people with 20/20 vision can see points that are 1/1500 of an inch, 20 inches away 1/750th of an inch, 40 inches away 1/325th of an inch, etc. So, it is an accepted photographic standard that the average person sees anything below that level as sharp.
At what viewing distance do different sized TV's reach that sharpness level where, if the image were any sharper, we couldn't see the difference?
It depends on the TV size and whether it is playing standard DVD's or blu-ray. The results in this study are based on the highest quality full res 1080P TV monitors and ideal playback conditions.
DVD sharpness only test:
A 40" diagonal widescreen TV reaches the limit where a viewer sitting closer than 13 feet away begins to see individual pixels and the overall images becomes less sharp, the closer they get. Sitting further away, the 40 inch TV individual pixel size for DVD playback is so small that most all people cannot see sharpness improve.
Blu-ray sharpness only test:
How does blu-ray help? It improves the image quality inside the normal viewing distance. You can get much closer, without the image starting to fall apart. However, at some distance, far enough back, the average user with 20/ 20 vision will cease to see too much difference in the blu-ray vs. DVD, because they are too far away to see the resolution bump.
Plan your home theater space?
Okay, you can stop puzzling over the charts, here are the numbers based on a home theater space. Unfortunately with DVD, you can never approach 30 degree viewing, let alone 45 degree which some people claim as ideal. For all blu-ray sets, 30 degree viewing angle is fine. There will be no degradation of image for getting this close. For standard DVD's to seem to match that sharpness, the viewer needs to be much further away where the monitor appears to be 14 degrees left to right. In other words blu-ray will always make a difference unless you watch TV from very far away.