Calibration Pitfalls

Even the best measurement instrument is helpless if the predefined parameters of display, projector or room are not correct. In the following cases, calibration will be extremely difficult if not impossible:

• Too much ambient light present in the room.
• Television or projector video electronic restrictions or limited control of the individual picture parameters.
• Limited dynamic range of the equipment in both inputs and outputs (in particular whiter than white and blacker than black).
• Equipment defects.
• Insufficient computing power combined with excessively complex video processing causing picture clipping as the system is overloaded.
• Noticeable conversion differences between the different inputs or input resolutions.
• Little or no possibility to save user-set parameters.

Picture calibration generally involves an intrusive operation in a very complex control system. It is important, therefore, to make compromises that do not exceed certain limits - but it is also important to recognize where these limits are. To prevent a well-intentioned action becoming a worsening nightmare, not just theoretical knowledge is required but also a deeper understanding gained through seasoned experience. Therefore, only have your display calibrated by someone who makes his daily living from performing these difficult procedures.

Since the measurements do not necessarily necessitate 1080p picture material, all the necessary test pictures for the Colorfacts PC-based color measurement system can only be found in the 720p section of the DVE High Definition DVD. The semi-automated determination of the color space according to CIE and D65 standard illuminant will only work if the test pictures are used in the following order (see below).

1 100% Green "Flat Field G 100%" 14. Test Picture

3 100% Blue "Flat Field B 100%" 15. Test Picture

4 100% Cyan "Flat Field Cy 100%" 16. Test Picture

5 100% Yellow "Flat Field Ye 100%" 18. Test Picture

6 100% Magenta "Flat Field Ma 100%" 17. Test Picture

7 100% White "Flat Field Y 100%" 06. Test Picture

Just as important as the measurements for so-called saturated colors are the grayscale tests, which are accomplished using the test imagery from the "Gray Scale Tracking" chapter on the DVE High Definition DVD. Here, the color temperature is measured for the complete scale from very dark gray to 100% white.

Ideally, the color temperature should correspond closely to the D65 point across the whole bandwidth, without any added color casting. Colorfacts also determines the Gamma and the brightness distribution across the whole gray spectrum.

Gamma and Gray Scale Tracking with the help of test imagery from the "Gray Scale Tracking" for Colorfacts chapter: (1) to (21) Pluge + Window 0 % to 100 % (in 5% graduations). All necessary test pictures for grayscale testing can be found in the 720p area of the DVE High Definition DVD.