I've had an HD-Ready set for over a year now and enjoy the few HD programs available in my area. I had a friend over the other night and was ask a question that I have always wondered about but never ask anyone myself. Why do HD broadcast have grey bars instead of black bars like wide screen DVD's? It really is far more distracting than the standard black you see with the DVD format. Is it a part of the electronics or is it in the signal itself? Any info would help. I hate it when someone ask me something about my system that I can't explain

Thanks in advance

Lasher

Are you talking about the gray bars on the sides of the 16:9 screen when viewing 4:3 material? At one time, I understood the gray bars to be used they are less prone to burning in, but I could be wrong.

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My bars are at the top and bottom. I have the Mitsubishi vs-60111 it was built in the 4:3 format but is hd ready. I bought it that way because most of the current SDTV programing is still in 4:3 but I wanted HDTV as well.(get the best of both worlds whenever possable )So what your saying is this was done to lower the risk of burn in but has never been changed on dvd? That's rather strange don't you think? I'm not saying that I don't believe you. It just seems a little silly to me to do that to one format and not both. I think the black is far less distracting. Thanks for the info

Lasher

[This message has been edited by Lasher (edited April 08, 2004).]

My understanding is that video black is supplied by a standard resolution DVD player above and below the image information area. Thus your television is receiving a normal NTSC full 4:3 ratio video signal and the DVD player can still use the full 4:3 area for menu and status icons outside of the picture area.

On your television, for an incoming signal from and HD source where the 4:3 ratio is not supplied, likely the television itself fills in with grey to accomodate your 4:3 viewing area.

GRAY or BLACK is set (in the scenario you are describing) by your TV manuf.

However, some models (I know some of the Sony’s) allow you to choose gray or black in your televisions setup menu other models allow no choice in the matter. (I prefer black, then my film is matted like a painting in a manner I find ascetically pleasing). There is some debate as to whether gray would 'burn in' slower than 'black' when wide screen is used often with aspect ratios requiring borders.
I once saw a valid argument stating that either color is as high a risk.
One reason I have an RP LCD, -less to worry about!

Check your TV’s setup you may have the choice.

PS: Hi everyone! Long time no post for me. Hope I remember my password!

BB4TB is in the right track. I sell consumer grade stuff at work. The difference is the source. Your dvd player is putting the black bars top and bottom of your picutre, whereas it's most likely your television set that is putting the grey bars up on HDTV programming. A quick test would be to tell your dvd player that you have a widescreen TV instead of a 4:3. At this point, the dvd will output in only widescreen and your tv will have to fill in the bars itself. This should make the two look the same.

these people are not entirely correct by saying that the bars are dictated by the hd signal, if you are watching an hd program (formatted 16:9) on a traditional 4:3 (hd) tv then you will always experience bars on top and bottom unless you zoom in. this is because hd tv is widescreen and to maintain aspect ratios the image is made smaller so that it can fit entirely inside the screen in relation to width only. the color of the bars WHEN WATCHING HDTV is dictated by your tv not the program. the signal is broadcast in 16:9 with no bars on top and bottom at all, when that signal enters your tv depending on your tvs ratio the picture gets adjusted. sometimes tv manufacturers allow you to change the bar color. ANY COLOR OF BAR AT ALL ON YOUR TV, PARTICULARLY PROJECTION TVS, WILL CAUSE "SCREEN BURN". BLACK BEING WORSE THAN GREY FOR "SCREEN BURN".

what you experience on dvds is slightly different. if you are watching a widescreen movie, it is likely not in hd standard widescreen (animateds usually are, and more and more are close enough). the movie could be recorded in 2.35:1,1.85:1, etc. aspect ratios which are not 1.78:1 which is the hd standard ratio. if you have a widescreen hdtv (16:9), when watching wider formats, i.e. 2.35, you will see black bars on the top of the picture for the same reasons why you do on hdtv programs (to preserve aspect ratio). these bars are dictated and recorded on the dvd. so if you have a 4:3 and are watching a widescreen movie you will have even more bars. on a 4:3 tv, when watching a widescreen dvd you could actually have black bars governed by the movie to fill up your tvs "widescreen" space, and then also black or grey bars on the top and bottom that are from the tv filling up the not widescreen space. I WILL REPEAT THAT ANY BAR OF ANY COLOR OR LOGO OR STOCK TICKER WILL BURN YOUR TV, AND IF YOU HAVE PROJECTION IT WILL BURN IT MUCH MUCH MUCH FASTER, BLACK IS THE WORST SINCE IT IS A COMBINATION OF EVERY COLOR... i hope this is clear enough... there is more to the bars than what i have just said, but i am only trying to answer your question...

So by saying that the dvd player is putting up the black bars on movies, and your tv is doing it on hdtv programming, how is that source controlled? i didnt realize the tv was pulling the hdtv program out of its butt, i thought it came in via cable, sat., etc. you are correct in what does what, but the source is not what controls it all the time. it is as i explained it above.

All CRT (cathode ray tube) phosphors become less efficient at radiating light with use, direct view or projection. Similarly with plasma-type flat screens.

LCD and DLP projection, as well as LCD direct view flat screens, are not subject to the same problem. With these technologies, the light source may dim or burn out over time and need replacing, somewhere between 1,000 hours and 60,000 hours of use depending on the method of creating the light.

With a CRT, the amount of light generated at a particular point varies by changing the amount of electron bombardment of the phosphor at that point. With LCD and DLP, the light is always being generated behind the LCD or DLP elements, but the amount of light you see at a particular point is regulated by how much is allowed or directed toward the viewing surface by those elements.

On a CRT, all colors (red, green and blue) near their maximum excitation are used to make an approximate white. If I take a CRT direct-view or projection system, feed a signal that shows a large white dot in the center of a black background image area and let it remain that way for too long, the phosphors in the white area become less efficient at showing light compared the relatively unused phosphors in the black area. If I later send a signal that provides an evenly distributed dull gray everywhere, I would see that the former dot area on the screen was slightly less bright. If the blue phosphors wear more quickly than the red or green while producing bright white, then the formerly white area may seem yellowish or brownish compared to the formerly black area. This type of ‘burn’ can occur in a plasma screen after just a few hours. A CRT projection system, because small CRT’s are driven hard, begin to ‘burn-in’ with a few dozen hours of unchanged image area. Direct view CRT’s usually take many hundreds of hours of unchanging image area to ‘burn-in.’

You might say, “I never show a white dot continuously on a black background.” The usual culprits are a television that always monitors a single channel that has a logo or lettering that stays on most of the time in one area while the rest of the screen gets a varying image or viewing a signal that does not fill the image area.

For television viewing where all portions of the image are constantly changing, the phosphors are wearing out slowly and approximately evenly everywhere. If the television is used the majority of the time for images that only use the center of the screen while the borders are black, when a full screen image is shown, the phosphors in the center will eventually appear not as bright and/or discolored compared to the border areas. The point of having gray borders is a compromise. The engineers’ idea was to wear out the phosphors in the border area at an average rate, hoping that the center area would, with varying bright and dark areas, not wear out more quickly or more slowly than the phosphors continuously being used at half brightness in the gray area. If the average-over-time brightness of the center area does not equal the gray border average brightness, eventually you will be able to see, when viewing a full screen image, the boundary that was between the gray area and the varying image area.

Obviously a black border area will never wear at the same rate as a varying image area. What is being relied upon are normal viewing habits. That is: most viewing will be full screen and only a minority of viewing time will use a limited area of the screen. Full screen use tends to reverse minor burn-in tendencies. So if full screen viewing is generously sprinkled in among partial screen viewing time, the burn-in effect either tends not to accumulate or tends to accumulate very, very slowly. Besides, as you know, consumers generally accept black borders and balk at gray borders.

If a CRT has a very minor burn-in, one ‘cure’ to attempt is to send a full-screen white signal to that CRT for 10 to 300 hours immediately after the burn-in occurs. This is similar in theory to lightly sanding a wood surface after the surface receives a very mild abrasion. Generally you are not “healing the wound” as much as bringing the rest of the surface to the same level so that the imperfection is no longer in contrast to the rest of the area and the abrasion’s edges are smoothed out a bit. The success of this cure varies.

I know I tend to go on for a long time, but I hope an engineering viewpoint from someone that works in television and presentation media has helped.

And ... welcome back SLL!

[This message has been edited by bestbang4thebuck (edited April 09, 2004).]

yeah dlps dont have burn, i shoud have said that. they do however have pretty rainbow effects to look at! and lcds have grid lines... this is why i find projection (rear or front) most film like, perhaps not the best for hdtv, but right now there is little hdtv and when it becomes standard there will be something better anyway...