SD picture quality

[anspenc51]

After reading many  revues I bought a 49"KD Sony 4k ultra hd TV. After 2 weeks of tweeking the picture settings I have a good HD picture but the SD quality is very poor (blurred) I have spoken to Sony who suggested I contact Sky to check there end. Sky engineer came and fitted a new power cable and a new dish. Picture quality improved slightly but still very poor SD. Any advice would be most helpfull as i'm on the verge of returning the set . ANDY

[Anonymous]

Hi there

SD pictures will always look poor on a large screen TV.  Thats why HD was invented.  Simply, you are 'blowing up' the imperfections of a SD broadcast to fit on a bigger screen.  Also, different channels are broadcasting different picture definitions and bitrates, so one channel can look worse than the other.

Without seeing a picture for myself, its hard to determine what you are seeing is entirely normal or actually really bad. 

Cheers

[anspenc51]

Thanks for the reply. I have been back to Currys (very helpfull) and did back to back comparisons with 6 different TV's including curved screens and all had the same results. Conclusion :- suppliers like Sky etc. are ripping us off by forcing us to pay for HD. What they will charge for 4K when it comes out i hate to think.

Thanks again.

[Anonymous]

Your welcome.

What I also think has happened over the last few years - I can only speak for Freeview and not Sky (but imagine it could be the same).  Freeview has seen an increase of channels - yes its true that more multiplexes have been added to the transmitters, but not nearly enough.  Freeview transmitters and broadcasting costs are expensive - it seems that they have decreased the resolution and bitrates to many of the SD channels and crammed as many as they can on same multiplex.  For example, instead of 10 decent quality SD channels, we now have 15 poorer quality.  Adding to the fact that a large screen will increase imperfections, and theres your problem.

Companies like Sky want people to PAY extra for HD.  So would imagine that they reduce the quality slighly - which also has a knock on effect of people perceving HD is also far better than what it is, as there is a bigger 'leap' in quality.

Cheers

[alex30 · Accepted solution]

Hi,

We must also remember that a SD television (if one exists today) will have approximately half a million pixels on it's screen. A Full HD TV has roughly two million pixels and a Ultra HD roughly eight million pixels.  The size of the screen does not alter the number of pixels, a large Full HD will only have the same number as a small one. 

When you feed a SD signal to a UHD TV it is only receiving enough information to fill half a million pixells worth of screen ( ie : Just a sixteenth of what is required to form a displayable image)and so it must fill iin the blank spaces by what is termed Upscaling.(By a factor of 16  !) Some TV's upscale better than others but , at the end of the day , it is an approximation and not exact.

This explaines why an Ultra High Def TV can look worse than a Full HD when playing standard def or full HD material as it has to upscale by a factor of 16 for SD or 4 for Full HD.

A Full HD TV only needs to upscale SD by a factor of 4 to get a playable image.

[rooobb · Accepted solution]

If the Sky decoder is connected (I assume) via HMDI be aware that it is also trying to upscale (depending on the setting for HDMI output to TV) and it may worse than TV upscaler.

I did set my HDD recorder to output at 576i on HDMI to my FullHD W805a and the image is far better than setting the recorder to output at 1080p..

Obviously in thi way you lose quality on HD image (that my HDD recorder is not capable to manage), but you may try some setting in the middle (I don't think SKY is sending any pure 1080p signal, 1080i if you're lucky)