Central to the concept of video calibration are the standards that are rigorously maintained in film and video production.

When it comes to image projection, an un-calibrated display means you are not seeing what was intended and may even be missing parts of the image. Proper calibration can optimise the performance of the chosen equipment in the important areas of contrast ratio and black level.

I’m often asked ‘What’s wrong with my TV?’ or ‘Why didn’t the manufacturer do this?’ Well, the final image is a combination of the source equipment and the display – in other words, the video system.

Lacking a crystal ball and unable to predict the source equipment and connection method, a manufacturer can be forgiven for choosing moderate settings. In many cases the manufacturer is likely to choose settings that will help with presentation in a showroom rather than produce an accurate image.

Some high-end equipment is built with an excellent range of controls and little regard for the standard settings, as it is expected that the display will be calibrated once installed.

Calibration is a separate process for each piece of video source equipment. The settings for the DVD player will not necessarily be correct for the digital TV receiver.

Settings for the source equipment are just as important as those for the display. If all sources are running into one input on the display, it may be necessary to use memories to hold the settings for each device.

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A lot of adjustments are done by eye with the appropriate test patterns, but when it comes to colour adjustments your eye is of little use.

To generate the appropriate test patterns you can use a test disc such as Digital Video Essentials. It is also important to use discs that match the type that will be played. For example, an NTSC disc is of no value when calibrating a DVD player to play Australian PAL discs. Similarly you shouldn’t use a DVD to calibrate a Blu-ray or HD-DVD player.

A full calibration requires a high-definition signal generator, such as the Sencore VP401. You can’t insert a disc into your pay TV receiver, so a signal generator is inserted to replicate the type of signal used.

Due to the fallibility of our eyes it is essential to use a colour analyser to adjust the display to broadcast standards.

Sencore and Datacolor manufacture PC-based instruments designed for home theatre calibration. There is a direct relationship between the performance and the cost of these valuable pieces of equipment, especially when considering low-light performance, which is essential for accurately calibrating a projection system.

You can achieve an enormous improvement on the factory settings when armed with an understanding of the functions of basic adjustments and a calibration DVD.

The Digital Video Essentials DVD is highly recommended, although it is notoriously difficult to navigate. I have listed the recommended title and chapters in parentheses for each test.

Brightness (12:9), which really should be called a blackness control, adjusts the level of the blacks shown by the display. Setting it too high means the blacks will be worse (greyer) than the display’s capability; setting it too low gives dark blacks but will also eliminate the darker information in the picture – known as ‘black crush’.

The correct setting will have the best blacks and will still show detail slightly above black.

Contrast (12:14) should really be called whiteness. No surprises, in that it controls the intensity or brightness of the whites.

Displays have a finite limitation on the maximum image brightness. Setting this control too high causes colour shifts or loss of detail in the bright part of the image; setting it too low will not distort the image but the display won’t be as bright as possible and the contrast ratio will suffer.

If correctly set, the contrast will be as high as possible with no loss of detail or colour shift at the bright end of the scale.

You want the image to be as detailed as possible, but you can’t extract information that isn’t present in the original source material by just turning up the sharpness (12:17). Setting it too high creates artefacts (things that don’t belong) on the edges of objects. Sure, it may look sharper but in reality there is less detail in the image, as the artefacts are obscuring sections of it.

Geometry, referring to the size and shape of the image, is adjusted with the aspect ratio control. Confusion is rife in the industry due to a lack of standardisation in names. What one brand calls ‘wide’, another will call ‘full’.

It is very important to tell your source equipment the aspect ratio or shape of the display (usually 16:9). Failure to do this is the most common video sin in the industry. In addition to seeing images that are distorted, you are throwing away at least one-third of the resolution by mismatching the source and display aspect ratios.

A circle grid pattern (12:20) will let you try each of the display’s modes. Choose the setting showing circles that are perfectly round on all sections of the image.

Finally, if you follow the guides on the test discs you will be looking through a blue filter to set the colour control for the correct saturation (strength) of colours. The filters are designed for phosphor-based displays and are completely inaccurate for lamp-based displays such as projectors and LCD flat panels.

Even if you have a phosphor display, like a plasma, the filter works only if you have already used a colour analyser to ensure the colours are correct. A quality reference scene (17:3) is your only alternative.

In an ideal world these controls would work independently of each other; in practice you will need to revisit the controls until they are all set correctly.

The investment in equipment for a full calibration starts about $15,000, and training is essential to get the best results. If your calibration requirements don’t justify this type of investment you can hire a trained calibrator with the right equipment and experience.