JAI RM-670, User Manual

Page: 38 / 82

RM-67X Series
38 Functional Options
Figure 34. ALC Advanced Set
•
ALC Window
These parameters define the rectangular Region of Interest (ROI) that will be used to calculate the ALC exposure level. The
user defines the upper left and bottom right corner of the ROI using X & Y coordinates. The ROI can target the center of
the image, or can be set to avoid a certain portion of the image so that its light value will not affect the ALC function. A
window display can be turned on to help the user identify his ROI, but it should be always set to off during normal
operation. The normal default of the ALC window is 90% of the full frame image.
•
ALC Mode
This allows the user to select the type of algorithm for the ALC function.
Average: The ALC level is based on the calculated average value of the selected window.
Peak: The ALC level is based on the calculated peak value of the selected window.
Log-Average: The ALC level is based on the calculated average value of the window, but using a log scale.
•
Bright Speed
This selection sets a time value to wait a pre-selected time before the ALC will adjust when the scene is changing from
dark-to-bright. For example, if the average scene level is 50 and it immediately changes to 100, the camera will verify that
the scene has stayed at 100 for the pre-selected time before it will adjust the ALC.
•
Dark Speed
This selection sets a time value to wait a pre-selected time before the ALC will adjust when the scene is changing from
bright-to-dark. For example, if the average scene level is 100 and it immediately changes to 50, the camera will verify that
the scene has stayed at 50 for the pre-selected time before it will adjust the ALC.
•
Weighted Log-Average
This selection adjusts the log curve of the log average algorithm.
• Impulse Filter
This selection sets a time value to wait a pre-selected time before the ALC will adjust when the scene is changing. It acts
like a hysteresis loop for the system.
•
Electronic Shutter
Setting the ALC Mode to “automatic” in the main control window causes the camera to begin working to maintain the
proper exposure, based on the settings in the ALC Level and AGC Max Gain boxes. When the Electronic Shutter box is also
checked, the Automatic Exposure Control (AEC) function of the ALC mode is enabled, causing the electronic shutter to work
together with auto gain to achieve the optimum ALC level. If this box is unchecked, only auto gain is used, which may be
insufficient to achieve the desired ALC level. This configuration (ALC on, Electronic Shutter off) is normally used only when
an auto-iris lens is connected to the camera. This allows auto gain and auto iris to control the exposure, while eliminating
the chance of any conflicts between the auto shutter and auto iris actions.