So which output setting should we have our Sky boxes set too. 1080i or Auto ? (for best PQ ). taking into consideration that 99% of the content I watch is in HD.

1080i or Auto is the same for HD, it only affects SD channels.

Watching HD using either setting gives 1920 x 1080 interlaced as transmitted.

Watching SD with Auto for the best SD channels gives 720 x 576 progressive leaving the TV to scale to 1920 x 1080 (assuming it's a 1920 x 1080 panel) - 576i if viewed by scart

Watching SD with 1080i the box scales the 720 x 576 to 1920 x 1080.

As already said try both watching a SD channel, use whatever you prefer.

As far as HD content goes it makes no difference whether you use the 1080i setting or Automatic.

The benefit with Auto comes only with SD content. Then it also depends on the TV settings. If you have all the manufacturer's picture "enhancements" turned on it'll probably wreck the SD picture enough to mask any difference. But if you set your TV up properly using a test disc including the colour filter then you should see the benefit.

ah I see. Thankyou to both for clearing that up for me

14:9 PAL broadcasts (as output by analogue TV stations pre-DSO) were (and still are in some cases) downscaled (and cropped) 16:9. Where this downscaling takes place is not relevant -- indeed the fact that it's the TV company doing the downscaling only serves to highlight the point -- they will use the best technology available.

Take 625-line picture, downscale to approx 545 lines with black bars top and bottom.

The principle is exactly the same; lose some lines of information and interpolate others (or interpolate all of them down depending on the technique used).

Result: mush.

So, explain to me again how downscaling is "easy"...

PAL 625 line UHF transmissions had 576 video lines, the same as SD Digital TV (49 have no video data).

1080i digital TV has 1088 lines (similar to 625 lines 8 have no video data).

As Graham has pointed out, you are wrong with your assumptions - downscaling is easy because you're not having to create something that doesn't exist (and getting it wrong more often than not).

Because you're not having to create something that does;'t exist you don't get artefacts generated, it's a MUCH, MUCH simpler process than upscaling - and all TV's etc. perform it excellently (even cheap ones).

Upscaling is where quality counts, with the quality of upscaling being the biggest difference between a cheap and expensive TV.

Abit of a bump this but just looking for help.

Just got Sky TV installed but only in SD with my HD ready TV. Is there anything I can change in the Sky display settings to improve the picture quality? I've got the output resolution set to auto at the minute.

Any advice would be appreciated!

Why only in SD?, the only boxes fitted for a years now are HD ones, and you get a decent number of free HD ones even if you don't take the HD subscription. So for BBC or ITV etc. choose the HD ones.

Presumably you're connected via HDMI?, so try setting the box to 1080i and see if that is any better than Auto, as it allows the box to do the scaling rather than your TV (so will be better if the box scales better than your TV does).

You could also try 720P, in theory that 'should' be worse for all cases - but you never know!

Sorry I meant the box is a HD one but no HD package, I wasn't aware of there being some HD channels available for free.

Will the SD channels look any different on any of the resolutions? Or should I just leave it on 1080?

Thanks

Yes, the same ones that you get free on Freesat.


Like I said, it depends on how well your TV scales - try all the options, and see which YOU find best - it's a personal setting, some people prefer one over the other.

There are 11 free HD channels.....

BBC ONE HD
BBC TWO HD
BBC THREE HD
BBC FOUR HD
BBC NEWS HD
ITV HD
CBBC HD
Cebbebies HD
4HD
NHS World HD
RT HD

Check 'em out in the EPG.

By and large a TV does a better job of scaling than a Sky box. The reason is to do with the number of steps involved in the scaling process as well as the quality of the processing being done. It breaks down like this...

The closer that the signal going in to the TV is to its original format then the easier it is for the TV to process it correctly. We rarely spend time thinking how a signal originated, let alone how that might affect the TV's scaling performance. But it is important. The signals we see could have originated from video cameras shooting in interlaced formats: 480i/60Hz, 576i/50Hz, 1080i/50, 1080i/60.... or in progressive video mode 720p/50, 720p/60..... or from film-based cameras shooting at 24 frames per second which is a form of progressive. (50Hz is the UK TV refresh rate, 60Hz is US and we see a lot of US sourced drama on UK TV). Much of this has to be converted to be compatible with 576i/50 which is what UK SD TV uses as a resolution and refresh rate. Some of these processes are flagged in a way that makes it possible to undo the damage that they cause. By sitting another layer of conversion by the Sky box from 576i to 1080i on top of what has gone before then it can obscure the flagging and make it more difficult for the TV to do its conversion to 1080p, presuming that that is the panel resolution.

Leaving the Sky box on Auto means that it plays out the image in a format that's closer to the original. The catch is that the Sky box takes time to switch modes between 576i and 1080i.

Fiddling around with the Sky box settings will have a 10% effect on picture quality. The other 90% will be affected by setting up the TV picture properly.

Thanks for the detailed response, I'll probably just the leave the sky on 1080i. I did have a look at the TV picture settings but couldn't find much on there. Will have another look though.