Barco R92112011, User Manual

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7. Advanced
7.8.5.4 Black level
Overview
• Introduction
• Internal black level
• Beta planes
7.8.5.4.1 Introduction
Brightness uniformity
In a multi channel system the brightness can vary over the different channels/projectors. The brightness level can be matched using
:
1.
CLO: in this case the light power is matched over the different projectors, see CLO in the Lamps section
2. Black level : this will act on the brightness of the “black” color of the image part situated outside the soft edge zones.
Internal black level versus Beta Planes
In the same way as for the soft edge adjustment (Internal vs Alpha planes) this black level adjustment can be fi xed internally by
using a dialog box or externally by uploading a user de fi ned Beta plane . This beta plane will contain the values for the brightness
offset to be applied to the image.
Both methods will allow to compensate for the typical double brightness phenomenon in the soft edge zones by increasing the
brightness of the rest of the image.
channel 1 channel 1
Overlap zone (double brightness)
channel 1&2
pulled up
Image 7-137
Black level : double brightness compensation
It is worth noting however, that (internal) black level (via the dialog box) is to be used for simple linear soft
edge zones (like in the illustration above). Curved soft edge zone should be done using (external) beta planes.
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