Camera attributes, Camera attributes -3 – National Instruments NI-IMAQ User Manual

Page 19

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Chapter 3

Programming with NI-IMAQ for 1394

© National Instruments Corporation

3-3

NI-IMAQ for IEEE-1394 Cameras User Manual

Before you can acquire image data successfully, you must open a camera
with the

imaq1394CameraOpen

function.

imaq1394CameraOpen

requires a camera name and returns a handle to this interface. NI-IMAQ for
1394 then uses this handle to reference this camera when using other
NI-IMAQ functions.

To establish a connection to the first IMAQ 1394 device in your system, use
the following program example:

SESSION_ID

session_ID;

if (imaq1394CameraOpen(“cam0”, &sessionID) == IMG1394_ERR_GOOD)

{

// user code

imaq1394Close(sessionID);

}

This example opens a camera named

cam0

. When the program is finished

with the camera, it closes the camera using the

imaq1394Close

function.

For a complete list of the available camera functions, refer to the NI-IMAQ
for IEEE-1394 Cameras online help.

Camera Attributes

Use camera attributes to control camera-specific features such as
brightness and shutter speed directly from NI-IMAQ for 1394. You can
also set camera attributes through the feature tab in MAX. All of the
configured parameters for a camera are stored in a camera (

.icd

) file. This

file is linked to a specific camera.

The following attributes are defined in the IEEE-1394 Based Digital
Camera Specification
—Brightness, Auto_Exposure, Sharpness,
White_Balance, Hue, Saturation, Gamma, Shutter, Gain, Iris, Focus,
Temperature, Zoom, Pan, Tilt, and Optical Filter.

To modify these attributes in C or C++, use the

imaqSetAttribute

and

imaqGetAttribute

functions. If your camera does not implement every

attribute specified, the functions return an error.

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