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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 resolution - sharpness

    Blu-ray resolution - sharpness



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.

ON a 80 inch TV playing back DVD , anyone sitting closer than 24 feet will begin to see DVD individual pixels. However, viewing beyond 24 feet, the viewer cannot see individual pixels anymore, so the image has little or no improvement in sharpness.



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.

For Close-up, a blu-ray will always look better than a DVD. An viewer sitting closer than 24 feet watching a DVD on an 80 inch screen, can see individual pixels. They cannot do that with blu-ray unless they are within 10 1/2 feet.

For normal viewing distances, blu-ray always looks better until the viewer gets so far away that they can no longer see the difference and DVD resolution begins to appear similar to blu-ray. For an 80" screen, this only starts to happen when the viewer is beyond 24 feet away. Some people with better than average vision, will probably still see a pronounced blu-ray improvement up to about 50 feet for an 80 inch screen.

If you have the smaller 40" screen and show a blu-ray, you are not taking as full of advantage of the better resolution. At close viewing distances, blu-ray always looks better, but after 13 feet for average eye-sight, the difference is less noticible and after 26 feet for better than average eyesight, the sharpness begins to look the same as a blu-ray on a 40" TV.

This does not take into consideration the other improvements of the codec compression for color, clarity, contrast, motion artifacts etc. that blu-ray technology has over DVD. This test is only for visual sharpness.



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.







DVD resolution on Widescreen TV's with full 720 x 480 playback



Viewing angle, left to right, at the distance of maximum sharpness for DVD playback is 14 degrees for all screen sizes. If you view a standard DVD at this distance / angle you will be at the limit of an average person's eyesight so it would be difficult to tell if the playback is a standard DVD or a better, blu-ray DVD. Moving closer, you should begin to see individual pixels. If you are closer than this distance it should be easy to see the that blu-ray resolution is better.



TV Size

Distance in feet of max sharpness

Comments

  • 40"
  • 12 feet
  • Most people's living room viewing distance is between 10 and 12 feet.
  • 42"
  • 12.8 feet
  • Most people's living room viewing distance is between 10 and 12 feet.
  • 44"
  • 13.1 feet
  • You now begin to need to sit further away then average to not notice that DVD is lower sharpness than blu-ray.
  • 46"
  • 13.8 feet
 
  • 48"
  • 14.4 feet
 
  • 50"
  • 15 feet
  • This is the max distance, most people will allow for sit down, full attention TV viewing.
  • 52"
  • 15.1 feet
  • Definite advantage now goes to blu-ray for sharpness. People normally do not sit more than 15 feet from a TV.
  • 54"
  • 16.4 feet
 
  • 56"
  • 16.7 feet
 
  • 58"
  • 17.4 feet
 
  • 60"
  • 18 feet
 
  • 62"
  • 18.7 feet
 
  • 64"
  • 19.3 feet
 
  • 66"
  • 19.7 feet
  • Even if someone were to sit this far away, there would be other chairs closer to the screen. Again, Blu-ray has a large advantage for living rooms this large.
  • 68"
  • 20.3 feet
 
  • 70"
  • 21 feet
 
  • 72"
  • 21.6 feet
  • A viewer closer than 21. 6 feet can start to see that DVD resolution is noticeably less than Blu-ray. Anyone sitting further away will not be able to see much difference.



Blu-ray resolution on Widescreen TV's with full 1920 x 1080 playback (square pixels)

Viewing angle, left to right, at the distance of maximum sharpness for blu-ray playback is 30 degrees for all screen sizes. If you view a blu-ray DVD at this distance / angle you will be at the limit of an average person's eyesight, so moving further away should result in the resolution remaining similar. Moving closer, you should begin to see individual pixels. The blu-ray maximum sharpness distance is always closer than the Standard DVD maximum sharpness distance. So, at watching blu-ray will allways look much better, out to the Standard DVD maximum resolution distances listed above.



TV Size

Distance in feet of max sharpness

Comments

  • 40"
  • 5.3 feet
  • This is very close to view. The pixel size is at the limit of 20/20 eyesight at this distance. Closer, we would notice resolution go down, further away, we will not be able to see much difference in resolution. A larger screen is useful.
  • 42"
  • 5.6 feet
  • Still very close. A larger screen is useful.
  • 44"
  • 5.9 feet
 
  • 46"
  • 6.2 feet
 
  • 48"
  • 6.6 feet
 
  • 50"
  • 6.7 feet
  • Still to close. A larger screen is useful.
  • 52"
  • 6.9 feet
  • Almost 7 feet viewing distance is about right for a small living room. The perceived resolution will lower if you sit closer. This is an optimal size for a small living room.
  • 54"
  • 7.2 feet
 
  • 56"
  • 7.6 feet
 
  • 58"
  • 7.9 feet
  • Middle size living room - 8 foot sitting distance.
  • 60"
  • 8 feet
 
  • 62"
  • 8.2 feet
 
  • 64"
  • 8.5 feet
 
  • 66"
  • 8.8 feet
 
  • 68"
  • 9.1 feet
 
  • 70"
  • 9.4 feet
 
  • 72"
  • 9.5 feet
  • The main seats should be at least 9 1/2 feet away from the monitor. People sitting closer will begin to see some pixelation.





Conclusion

  • This shows a big advantage to blu-ray for resolution improvements based on 20/20 eyesight being able to resolve small points of light.
  • All viewers should easily be able to see improvements with blu-ray at normal distance viewing.
  • Some mid-size HD screens showing blu-ray are more appropriate for small to average living rooms.
  • Some customers, who view their television from unusually far away, may not benefit from blu-ray for smaller HDTV sizes.


Notes

Blu-ray authoring has many more advanced video filters and encoding options than standard DVD's. Filters to improve the blacks, grain, edge contrasts and other image improvements are far beyond what standard DVD authoring can do. Watching a moving video is much different than examining a still photo. This study is based on the photographic standard and the difference of perception with video is not covered at all. It is probably true that most people will find blu-ray to perform better even beyond the distances listed above.





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