Inside Macintosh: QuickTime Components /

Chapter 8 - Video Digitizer Components / Video Digitizer Components Reference

Video Digitizer Component Functions / Controlling Analog Video

VDSetContrast

The VDSetContrast function sets the current contrast value. The contrast value ranges from 0 to 65,535, where 0 represents no change to the basic image and larger values increase the contrast of the video image (that is, increase the slope of the transform).

pascal VideoDigitizerError VDSetContrast
                               (VideoDigitizerComponent ci,
                                  unsigned short *contrast);

ci

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

contrast

Contains a pointer to an integer that contains the new contrast value. The video digitizer component attempts to set the contrast value to the value specified by this parameter. The digitizer component returns the new value, so that the application can avoid using unsupported values in future requests.

RESULT CODES

noErr	0	No error
digiUnimpErr	-2201	Function not supported
qtParamErr	-2202	Invalid parameter value

SEE ALSO

Your application can obtain the current contrast value by calling the VDGetContrast function (described in the next section). To retrieve the recommended contrast value, your application can call the VDGetVideoDefaults function (described on page 8-66).

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