Philips’ HD-Ready 42PF9631D - its first 1080i plasma

Quote from report "it isn't so much screen size and resolution that counts.."

That's not true, Toshiba, Philips and Sony said resolution does matter. (See "1080p HD questions answered" - April HDTVUK 2006).

This is a 1024x1080 = 1,105,920 pixel display
The full 1080i is 1920x1080 = 2,073,600 pixels.
So only 53.3% of the 1080i picture can be displayed.
(As there are 1080 lines on this display, the pixels must be rectangular 1920/1024 = 1.875 times wider, than their height.)

For their LCD televisions the manufacturers are effusive in their praise of pixel resolution, this from Sony:

"Experience the Wonders of Full HD 1080 Pictures with the BRAVIA X-Series

March 3, 2006 - The BRAVIA X-Series is designed to deliver a definitive viewing experience – full HD resolution pictures and true-to-life colour. Precision colour reproduction and the very highest screen resolution combine to create a picture that seems almost alive. Stand-out features include a Full HD (1920 x 1080) LCD panel, Live Colour Creation, which uses a wide spectrum backlight (WCG-CCFL) and the newly developed BRAVIA ENGINE EX, Sony’s unique intelligent picture enhancement technology. Capable of receiving 1080p signals, the BRAVIA X-Series twin HDMI inputs will ensure compatibility with the expanding HD environment in Europe as well as with high resolution, Full HD (1920 x 1080) signals in the future. Unlike most other TVs, the BRAVIA X-Series isn’t just HD-Ready; it’s Full HD-capable. Instead of scaled images which have been digitally reduced to fit lower-resolution panels, Full HD reproduces HD1080 picture exactly as it was transmitted. This is the key to a picture of the highest possible quality."

Or paraphrasing: "Scaled images digitally reduced to fit lower resolution panels are a bit rubbish really, you will not see the picture exactly as transmitted, or have a picture of the highest possible quality."

It is possible to make 1920x1080 plasma displays, and I think it is wrong to describe a 1024x1080 display as a 1080i HD Ready display. EICTA is to blame in failing to insist on 1080i/p meaning a minimum 1920x1080 pixel display.

While regular HDTVUK readers may be able to work through the confusion, a simple solution occurs to me, to stop the mis-selling of "HD-Ready". People buying 720p "HD Ready" sets are only getting 44.4% of the HD1080 picture, yet most are expecting to get the full Monty, when BSkyB HDTV starts. They will be disappointed when they see the full 1920x1080 pictures.

Instead of allowing the "mis-selling" that allows a 720 line x 1024 pixels per line plasma television to be described as "HD-Ready", express the percentage of the "Full HD1080" picture on the labels.

For a 1024x720p = 35.6%(HD1080)
This Philips 1024x1080i = 53.3% (HD1080) etc.

That should clear up the confusion, for most people.

Whether the HDTV signal/picture is interlaced or progressive is now virtually academic, because conversion from one to the other is well established technology, originally for PC-card TV tuners. The i/p designations can almost be taken to be 25 frames per second and 50 frames per second (30/60 in the USA)- and because of improved refresh rates LCD/plasma displays no longer need the higher frame rates to eliminate movement blur.

In reply to Ian - this may not be the right place to comment about image processing techniques, but as Philips have done so, why not.
Because I'm a bit worried about your last comment, the TV final picture quality that Philips were talking about was the display of SDTV 576i pictures, in relation to "interpolation".

The image processing options available for square pixel CRT/LCD displays are reasonably standardised. The techniques that are individual to each manufacturer, arise from using rectangular pixels on plasma displays, but by now they all should be getting these re-pixellation processes right.

For digital television LCD displays, the square pixels broadcast are displayed as square pixels. There is a lot processing to get from the MPEG2/4 broadcast program stream to the output display frames, because picture groups have to be reconstructed as individual frames, the sound stream separately processed etc. But within the processing there are some fairly standard additional user picture processing adjustments, such as contrast, hue etc., where the most important are probably the composite ones such as the proprietary Eagle vision (e.g. in Power DVD, but licensed also to Thomson receiver/set-top-box products), and edge enhancement.
There should now be enough adjustable LCD picture properties in any make of television and receiver (set-top-box), that manufacturers claims about their proprietary systems can be taken with a pinch of scepticism.

Edge enhancement is the one that seems to affect current viewing most. The early related programs were for making scalable type faces, and those program techniques were refined for dealing with the edges of objects during picture scaling which became the beginning of JPEG picture processing. Then the programs were further developed for using with compression techniques, that led to MPEG1/2; which gave us video streaming that only needed some full reference frames and groups of difference-pictures, so that all the full frames could be reconstructed. MPEG4 is further refinement of compression, saving bandwidth, that seems most improved in sound rather than pictures, where AAC sound is clearly better than MP3 sound, at 128kbps.

The peculiar thing that happens at the moment is that edge-enhancement is often happening twice. First when the broadcaster uses MPEG2/4 processing, for off-line encoding or during live real-time transmission. The television viewer's set-top box is adding further edge enhancement when decoding the received transmission. There is a double dose of edge enhancement, and that is good in some circumstances, such as transforming a fuzzy fast moving football into an object with a sharply defined outline.

But it is bad in other circumstances, such as high quality make-up just about covering and eliminating sight of an actresses poor complexion in the past, but using MPEG2/4 every blemish gets picked-up and edge enhanced by the broadcaster, then further emphasised by the edge
enhancement in the receiver set-top box. The way to deal with this is to have the edge enhancement on for the picture mode perhaps described as "sport", and have edge enhancement off for another picture mode ("mild" on my television). Better TV camera lens and recording processes/materials, mean that a 576i SDTV display on a 625-CRT television, already shows up poor complexions, and I found the BBC's "Rome" and "Hotel Babylon" difficult to watch on Freeview 576i because of the poor complexions of some of the lead actresses.

Refresh rates on LCD televisions are now fast enough so that movement blur is a thing of the past. The main LCD issue left is the limited viewing angle, but these are now generally so good that they are not a significant issue for the majority. Refresh rates on plasma screens are now fast enough to eliminate motion blur too, but they have other problems.

Plasma screens could not be readily made with square pixel 1280x720 and 1920x1080 displays initially. One of the solutions was not to build what was needed, but make what they could. That's why we ended up with 1024x720 pixel plasma screens described as "HD-Ready", although not even capable of displaying all the 1280 pixels per line. To fulfil the "HD-Ready" requirement these sets had to be 16:9 wide-screen, so they made the pixels rectangular. The non-square pixel processor, has to change a line of 1280 pixels into a line of 1024 pixels, inevitably losing picture definition most of the time, and must realign the edges, which is where the edge-processing works overtime.
Making what they could, has lead to other common plasma display panels of 1024x768, 1024x1024 and the 1366x768. (also USA 852x480 type is available in UK).

As none of these matches 1280x720 or 1920x1080, they do not have square pixels, but various rectangular pixels instead. The plasma display processor has to create the frames from the broadcast stream, resize and re-pixellate the picture by altering the pixel size, and then reprocess for edge alignment, after which the composite adjustments such as Eagle vision can be applied. This applies to most 720p plasma displays.

So for this Philips television, for 720p broadcasts, one stage of what the processor does is to create 1024 rectangular pixels from the 1280 square pixels. But that is the opposite of interpolation, they have reduced the pixels per line not added to them. Their press release does not relate to HDTV processing when talking about "interpolation".

Philps said, quoted: “Through interpolation, the Pixel Plus 2 HD matches the input source to the display’s resolution and then adjusts the values of the interpolated pixels to ‘fuse’ more accurately with surrounding ones, drastically boosting sharpness and detail clarity.”
This appears to mean that for this television they are doing the normal processing required for non-square pixel plasma displays; but they are obfuscating in not saying why or where interpolation is used. Interpolation is "to insert or introduce between other elements or parts", but as this television can only display 1024 pixels rather than 1280 pixels, the interpolation cannot be applying to a 720p/i broadcast. Bearing in mind that the pixels are rectangular, the interpolation that can be readily applied to the words, is for 576i.

Philips are not misleading to make themselves liable to mis-selling, if the only way of introducing synthesised "interpolated " pixels is in a 576i picture. They are being economical with the facts when writing about SDTV 576i, that has 576 lines by 1024 pixels per line. The main problem here then, is the 576 lines broadcast have to be "interpolated" to fill the 1080 lines of the display. And the maths does make sense, take the rectangular ratio pixel factor from my initial comments 1.875, and multiply, 1.875x 576 lines = 1080 lines.

What Philips are saying is that they create 1080 - 576 = 504 new lines of pixels, by averaging the nearest adjacent pixels, and then they have to edge-enhance the pixels for the edges of resultant scaled objects, to line up the edges. This is a tough processing requirement, because it is not a simple doubling up, the picture has to re-pixellated to effectively make the pixels 1.875 higher than the original square pixels. In fact it amounts to restoration of the square pixels, because the (576i) 1024 pixels per line are being stretched when displayed on pixels that are 1.875 times wider than square (from the requirements for the 720p picture display). But the edges were originally sharp, so as good as the processing may be, this is a lot of messing about with an original square pixel picture, in order to display it on rectangular pixels; and in highly detailed pictures it cannot be as good as the original square pixels displayed on a CRT/LCD display.

What Philps are saying about interpolation is marketing spin, totally misleading to anyone who does not understand what they are doing, and likely to be used by salesmen in Dixon's (et al) as "Philips say it makes the "HD Ready" HDTV television pictures better". No it doesn't, interpolation makes the best job it can of displaying the 576i picture. Freeview and Sky SDTV digital signals set-top-boxes do not contain ratio selections for anamorphic processing to match the particular rectangular pixels that the manufacturer has used. The manufacturers therefore have to build in SDTV receivers with individual customisations for rectangular pixels, in order that their "HD-Ready" sets can display 576i SDTV.

On a square pixel plasma display this is not necessary, but to paraphrase one again, will they say that such televisions: "do not require inferior interpolation to try to match the pure, sharp, original transmission, to non-square display pixels at lower resolution, which inevitably loses detail and sharpness; compared to the plasma display with one-to-one-pixel square pixels that retain original sharpness and clarity."
I wouldn't bet on it!

My advice, is don't buy anything until you have seen the 1080i broadcasts on more than one 1080x1920 pixel display. I'm going to wait for a 1080p LED projector, which may take some time, and even when I get one I will probably continue to watch most programmes as 576i on a 625-line-CRT wide-screen television for many years to come.

Question for brian if I may.

Your logic and explanation is exceptionally helpful; thank you.

I want to buy a new plasma or LCD 42", but am now wondering that I might as well just buy an EDTV 852x480, as unless I buy a 50" with true 1080i, then I am not going to notice anyway. Plus I move around frequently and my TV signals are all satellite; british, German and French.

Any advice would be much appreicated.