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Chapter 8 - Video Digitizer Components / Video Digitizer Components Reference

Video Digitizer Component Functions / Controlling Analog Video

VDGetInputGammaValue

The VDGetInputGammaValue function returns the current gamma values. These gamma values control the brightness of the input video signal.

pascal VideoDigitizerError VDGetInputGammaValue
                              (VideoDigitizerComponent ci,
                               Fixed *channel1, Fixed *channel2,
                               Fixed *channel3);

ci

Specifies the video digitizer component for the request. Applications obtain this reference from the Component Manager's OpenComponent function.

channel1

Contains a pointer to a fixed field that is to receive the gamma value for the red component of the input video signal. The video digitizer component places the appropriate gamma value into the field referred to by this parameter.

channel2

Contains a pointer to a fixed field that is to receive the gamma value for the green component of the input video signal. The video digitizer component places the appropriate gamma value into the field referred to by this parameter.

channel3

Contains a pointer to a fixed field that is to receive the gamma value for the blue component of the input video signal. The video digitizer component places the appropriate gamma value into the field referred to by this parameter.

RESULT CODES

noErr	0	No error
digiUnimpErr	-2201	Function not supported

SEE ALSO

Your application can set the gamma values by calling the VDSetInputGammaValue function (described in the previous section). To obtain the recommended gamma values, you can call the VDGetVideoDefaults function (described on page 8-66).

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