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HOW TO IMPROVE THE DEFINITION OF A TV PICTURE: Watch in TrueColour

Your TV factory settings are to make it look good in the showrooms. That's why it's in your living room. But over time, the settings may change through ageing components, the kids capture the remote or you have your own personal preferences.

Most people are unaware of the potential of the definition that is available. So let's start at the beginning. A picture (video) signal is sent to your home that includes black-and-white and colour information. No picture information can be sent brighter than white or darker than black. If you turn up the brightness, black shadows becomes only dark grey shadows. you cannot see blacker than black! Some TV soaps seem to be made in the dark and they keep the curtains or blinds closed in the background. It's not your TV!

You may not be aware that the colour information is about half the definition (or detail) of the black-and-white signal. Therefore, in certain circumstances, where there is high colour, your overall definition is effectively halved.

Your TV set also has physical and electrical limits. If you turn the brightness or colour controls full up, there is a trade-off between GAIN and DEFINITION due to the way electronic amplification works, especially for older CRT televisions. More gain could mean less definition.

Try this test: Go to a text page such as Teletext and adjust the contrast and brightness controls and watch what happens to a single letter, preferably a full stop - it will probably 'bloom' or grow in size as you turn it higher.

What can you do? Plenty actually. There are two strategies to optimise a TV picture:

User - What you can do and Technical: What an workshop engineer can achieve.

Let's start with the User tips:

1. Reduce the colour control to zero so you are displaying a black-and-white picture.

2. Adjust the brightness and contrast controls to mid-position.

3. Find a channel which is devoted to Text. This could be CeeFax, Sky text S4C/2 (where available) etc.

3. Adjust brightness and contrast controls so that:
A. In the black areas, the lines of the picture are just visible . Remember you won't see anything blacker than black. (You can check also this later when watching a channel showing a widescreen film where there are black bars top and bottom of the screen.)
B. The White of the picture turns from light gey to JUST white. Hopefully, this is well before the point at which the picture begins to 'bloom' or spread.
You may find you have to use a combination of both contrast and brightness controls to find the optimum point.

4. On-screen graphics are usually sent at 100% colour saturation which means you can adjust for the optimum amount needed. Adjust the colour control until a colour graphic is just 'loaded' with colour, then just back it off very slightly. If the colour looks flourescent, that's WAY too much colour. If necessary, compare the level of colour with an independent source - e.g. a web page. This allows you to discern the 'true' colour.
This 'true' colour can be checked with outdoor camera shots. Good neutral sources are the BBC's Antiques Roadshow or Channel Four's 'Time Team' where the lighting is natural sunlight and skin tones should look natural; NOT Kilroy orange or flat biege. Skin tones are quite subtle. Try looking at skin tone from the perspective of an artist. Remember that makeup is used on presenters and actors, including the men. Grass is not primary colour green but is much lighter because there is usually other plants mixed in with it. Studio shots are poor light sources, for the studio lighting has a narrower spectrum, giving people a cartoon look.

5. Congratulations, You're done!

NOTE: The colour control is now probably set at a significantly lower level than that at what you are used to. Please be prepared for resistance when your family/significant others view the TV. After you have optimised it; You are likely to get remarks such as:

"It doesn't look right"
"It looks horrible"
and "You've done something to that TV".

They will judge the picture from what they are USED to watching. "TV pictures 'should' be overcoloured!"

The picture you now have (and to which they will become accustomed) is more true to life. You are likely to see much more detail, different shades and styles which directors of films and programmes wanted to use to represent the mood of the film. Much of which you may have missed before. Advertisements in particular, are highly coloured.

Now for the Technical tips.

WARNING: These tips are for the use of a qualified engineer only! TV sets, particularly older sets with cathode ray tubes (CRT) contain circuits that generate KILOVOLTS, with the emphasis on the KIL! You can also destroy digital circuits with static electricity generated from clothing, carpets and movement etc. If you are unqualified, please leave well alone. A TV costs 100 - 10000. You on the other hand are priceless.

1. FOR CRT sets, Readjust the focus control (yes! there is one!) so the CRT beam output is at the sharpest setting - e.g. the smallest spot size. Most circuits are out of alignment through age or poor previous setting up. The sharpest setting is recommended because the set is normally viewed from five screen widths - approximately 4 metres away for standard definition TV's - (10-12 feet in old money).

2. Using the (usually) hidden on-screen menu, Adjust the picture height and width critically to the edge of the screen. (for the correct ratio). Most TV CRT sets overscan by 10% and Flat screen TV's can under-sample the available data. As the lines increase in density, it means the resolution will correspondingly appear to increase by a similar amount after adjustment.

3. Adjust the colour foreground/background controls so that dark grey IS dark grey, without any (colour) tint and that bright white is the 'correct' white, again, without any hint of colour. In the factory, the picture is set to look slightly blue in order to sell the set. The engineer can set it so it is pure white (Luminance 'C' or 'D').

4. For Flat Screen TV's, select the picture of 1:1 pixel matching where possible. Some rescaling introduces picture artifacts which can significantly can impair the picture.

5. For all sets, reduce distorion to the minimum by selecting the correct format. So for an older programme, if it is shown in the older squarer format of 4:3, resist the temptation to 'stretch' it to fill the screen. Furthermore, resist the temptation to stretch a stretched picture. That is NOT a good look!

Congratulations! you've now got a picture that shows the original source as it was intended by the programme's director. You could find that visitors to your home may even comment on the quality of the picture!

 

 
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