SD Picture Quality

UKTV never had 14:9 copies of The Bill, before the switch to 16:9 they always showed it cropped to 4:3. Presumably that's how Fremantle distributed 4:3 copies of 16:9 shows.

The deinterlacer in the sky box is toxic to the picture, especially when outputting to 576p. Letting it output at 1080i means it just upscalea, and looks MUCH better as a result.

You have to deinterlace before you upscale. It's the law .

If it looks better, it means the Sky box is a better upscaler than your TV (which also always upscales from 576p, it's similarly inescapable).

It's the 50i to 50p in the sky box - interpolating that extra space, that wrecks the image. The 1080 option keeps fields as fields, without creating imaginary gaps between temporal images.

Interlaced video still needs to be deinterlaced before it can be upscaled, even if the target is interlaced video (actually that's even true even if you're down scaling, if you want to do it right)

And that interlaced video will then need to be deinterlaced again by the TV, so if you can, you're probably better off letting the Sky box output 1080p - I assume this is an option.

Some older TVs won't accept a 1080p input, though, so if you set the Sky box to 1080i, the chain will go 576i->576p (deinterlace) ->1080p (upscale) ->1080i (reinterlace for HDMI to the TV) ->1080p (internal deinterlace by the TV).

Not an option on Sky+, which only does 576, 720p and 1080i.

However the OP is SkyQ, which can do 1080p:
https://www.sky.com/help/articles/changing-the-screen-resolution-setting

Spoke to those lovely people at Sky today and they did say it is probably because the original output was in SD and the SkyQ box transmits the signal in a higher resolution to the TV than the original picture and as it's such a big TV then it's stretching the programme more than it should.

Apparently, according to Sky, SD programming looks best on a TV 32" or smaller and HD 37" or larger. UHD broadcasts are aimed at 55" or larger.

So all-in-all although there's not a lot they can do (and the Sony TV is showing an SD picture on SD channels and HD channels on HD - it automatically switches between the two) I'm happy with their, and all your, responses, so thank you!

I wonder if the Trafalgar Group will come up with a good de-interlacer

There is something they can do, up their SD resolution to 720x576, it will never happen even though Sky believe in better.

I had a watch of The Chase on Challenge earlier, not sure what is going on, not low bitrates I don't think, all the captions seem very 'pixely' for example, like they are playing out a web viewing copy or something. Similar to how SD adverts look on HD channels. Other widescreen shows on the channel seem fine.

You'd think with the amount of modern commissions they're getting they'd be same to justify a HD channel by now.

Then it's doing a very poor quality upscale then... If you scale in the field domain you are throwing away a LOT of vertical resolution as you are effectively upscaling 288 to 540 for every field. Any decent 576i to 1080i scaler will deinterlace to 576/50p and then upscale from 576p to 1080i (either by doing a 576p to 1080p upscale and then a reinterlace - or possibly doing a 576p to 540line field-based downscale)

(*) This was true of DVEs too. Cheap DVEs did field-based scaling (and thus looked horrible when they zoomed. High-end DVEs like Kaleidoscope (and the bodged Encore in Flash Harry) did frame based scaling by deinterlacing first...


Also - if you run your Sky+ HD box in 1080i you lose aspect ratio switching for native 4:3 576i broadcasts as the Sky box won't pillarbox (or certainly didn't) This only works in Auto mode - or did - where 576p output is accompanied by aspect switching info.