Metrologic Instruments IS4910 Series Automatic Brightness Adjustment APIs

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Automatic Brightness Adjustment APIs

The set of automatic brightness adjustment APIs allows an application to automatically adjust the

camera’s gain and image integration time based on the quality of the previous images.

This function adjusts the IS4910 camera’s gain and/or image integration time (exposure) based on the

known quality of the last image and the desired correction, in dB, to this quality. The quality of the image

is presented by the number between 0 and 100, with 0 being extremely poor quality and 100 being an

excellent quality.

The flags parameter indicates whether the gain and/or image integration time (exposure) are allowed to

be adjusted, and whether the new values should immediately be applied to the camera or postponed until

and applied upon the next image acquisition. Note that in the snapshot mode adjustment of the image

integration time is not allowed regardless of the flags parameter.

The function calculates the most optimal values of gain and exposure within their allowed ranges, see

functions camSetAutoGainRange_db() and camSetAutoExpoRange() for details.

Prototype:

int camAdjustBrightness (int cam_handle, int cur_quality, float correction_db, unsigned long flags);

Parameters:

cam_handle - [in] handle to the camera device returned by the camOpen function.

cur_quality - [in] quality of the last image, from 0 to 100, or -1 if correction should be done

regardless of the quality of the last image.

correction_db - [in] desired level of brightness correction, in dB.

flags - [in] bit-combinatory value specifying whether the gain and/or image integration

time (exposure) can be adjusted, and whether the new values should immediately

be applied to the camera or postponed until and applied upon the next image

acquisition. The individual bit values are:

• CAM_AUTOGAIN, gain can be adjusted

• CAM_AUTOEXPO, image integration time can be adjusted

• CAM_APPLY_INSTANTLY, new values should be applied immediately

Return Value:

0: Success; -1: Failure

This function enables or disables the automatic brightness adjustment. If it is enabled then the IS4910

camera’s gain and/or image integration time (exposure) will be automatically adjusted after each image

acquisition based on the calculated quality of the currently acquired image.