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RGB Lookup Table Dialog
The RGB Lookup Table feature allows the user to modify and transform
the original video data. The pixel values for each of the R, G and B
components can be mapped into new values. The mapping from input to
output values is defined in a lookup table ( LUT ) file. The LUT file is an
ASCII text file that can be created and modified by the user ( see
Appendix A for details ) or can be automatically generated by the HD-SDI
Express application.
Gamma
Correction and custom Lookup Tables using the GUI
Gamma correction is the process of compensating for the non-linearity of
CRT displays. The HD-SDI Express application can automatically create
gamma lookup tables. It can also create custom lookup tables using an
interactive drawing feature.
Figure 7 – RGB Lookup Table dialog
Gamma/Pencil
This pull-down menu specifies the ‘gamma’ or ‘pencil’ mode of operation.
In the ‘pencil’ mode, the user can use the mouse to draw the desired
transfer function directly on each graph.
In the ‘gamma’ mode, the user can enter an explicit gamma value or use
the up/down arrows to increment/decrement the value or move the slider
to the desired value. Using ‘G’ as the gamma coefficient, the gamma
correction equation is:
Output_value = [(Input_value/255)
G
] * 255
Reset
This button sets the gamma edit box to a value of 1.000.
