Cheetah Pregius Camera with Camera Link
–
User Manual
July 6, 2018
Page
45
of
64
Rev 1.1
4 Camera Features
4.1 Exposure Control
During normal camera operation with exposure control off, the readout frame time
determines the exposure time. However, the
camera’s
electronic exposure control can
precisely control the image exposure time under bright light conditions. The electronic
exposure control does not affect the frame rate; it only changes the exposure time. When
Internal exposure control is active, the camera controls the start of exposure so the new
exposure ends just as the readout of the current frame ends and the readout of the next
frame begins. The maximum exposure is equal to the frame time, and the minimum
exposure is about 25 microseconds.
4.2 Automatic Exposure Control
You can set the camera to automatic exposure control (AEC) to keep the same image
brightness during changing light conditions. You can enable both AEC and automatic gain
control (AGC) independently or together.
In AEC mode, you can set the image luminance (brightness) target, and the camera
adjusts the exposure accordingly. The slave Area of Interest (AOI) supports a mode where
the camera adjusts the exposure to maintain the target luminance calculated only within
the AOI. You can select the target luminance to be either the average luminance or peak
luminance within the image or within the AOI. The camera adjusts the exposure starting
within the preset limit established by the user-specified minimum/maximum limits. When
AEC and AGC are enabled, exposure is always varied first until the exposure reaches the
maximum limit. The camera then indicates the limit has been reached and begins
increasing the gain until either the luminance target is achieved or the maximum gain
limit is reached. You can preset the speed of convergence (how fast the camera stabilizes
after an illumination change) from four possible rates. Slower convergence rates are more
stable than faster convergence rates, if the illumination levels change quickly over a wide
intensity range. The camera displays the current luminance, current exposure, and current
gain. For auto gain control, refer to Automatic Gain Control (AGC) section.
In some rapidly changing and bright light conditions, an image brightness oscillation
(image intensity flipping from bright to dark) could occur. To prevent this, increase the
AEC minimum exposure settings, decrease the convergence speed, increase the target
luminance level, or change the AOI or the lens iris.
4.3 Automatic Gain Control
Automatic gain control (AGC) enables the camera to maintain the same image brightness
during changing light conditions. In AGC mode, you can set the image luminance
(brightness), and the camera will adjust the gain accordingly. Luminance options are
average or peak.