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Video signal processing
5.5 Rendering intent
It is important to realize that the following statement is wrong:
"The video signal must be decoded at the display side in such a way to guarantee a linear system
transfer (a linear relation between the scene luminance and display luminance, called 'scene-to-
screen' or 'end-to-end' transfer)"
The mathematical inversion of the Rec.709 encoding equation that guarantees a linear end-to-end
luminance transfer is:
⎧
V
'
709
⎪
⎪
4
5 .
=
⎨
L
+
⎛
⎪
V
'
. 0
099
⎜
709
⎪
⎝
⎩
. 1
099
However, because of the linear offset, this inverse does not correspond to an effective gamma of
2.2, but rather to an "effective gamma" of around 2.0 (as discussed in the section "effective
gamma" and illustrated in the figure below).
Figure 56: The inverse of the Rec.709 encoding function fitted with a power function
158
Barco - RHDM-1701 - User manual
≤
<
0
V
'
. 0
018
709
1
≤
≤
⎞
. 0
018
V
'
. 0
45
⎟
709
⎠
1
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