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Calculate Gain
The Calculate Gain command measures the
inverse electronic gain of a digital camera. The gain is expressed
in terms of either electrons per Analog to Digital Unit (ADU) or
Digital Number (DN), as "e-/ADU". Detailed results of the
calculation may be listed in the
Message Pane.
Properties of the Calculate Gain
Properties
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Flat 1
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Select the first flat frame image from the
Image Set.
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Flat 2
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Select the second flat frame image from the
Image Set.
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Bias 1
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Select the first Bias frame image from the
Image Set.
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Bias 2
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Select the second Bias frame image from the
Image Set.
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 Use Cursor ROI
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Check this box to calculate the gain using only
the region of interest defined by the Image Cursor Otherwise, the
entire image is used.
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Update Image Headers
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Check this box to enter the calculated gain into
the image header using the
GAIN keyword.
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Click this button to calculate the gain.
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[List Summary]
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Click this button to lists a summary of results in
the
Main Messages Pane.
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Procedure
Best results are obtained if the Bias frames are
taken sequentially and the flat frames are taken sequentially and
exposed to the same illumination. As a by-product of the gain
calculation, this command also reports the readout noise (or
fundamentally base level of noise) produced by the camera.
Making this measurement requires opening 2 Bias
frames and 2 flat frames (4 images) as an
Image Set. The image set may have more images but you
must select these 4 images from the set.
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Open an
Image Set containing 2 Bias frames and 2 flat field
frames. Make this the top-most window.
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Click the Measure > Diagnostics >
Calculate Gain command to open thedialog.
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Using the 4 image selection controls, select the
2 Bias frames and 2 flat field frames from among the listed
images.
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Using the Use Cursor ROI option, choose whether to use
the entire image for making the measurement or to limit the
measurement to a region of "good" pixels. This is a statistical
measurement and you do not want blank pixels or image defects
affecting the statistics. Repeatable hot pixels or dead pixels in
the Bias frame, and flat field irregularities such as "dust donuts"
have no significant impact on the measurement.
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Click to perform the
calculation.
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To view details of the measurements and the
calculation, click [List
Summary].
Results in the Detailed Summary
The picture below shows typical output in the
Message Pane after clicking [List Summary]::
Related Topics
Camera Diagnostics
Calculate Readout Noise
Mira Pro x64 User's Guide, Copyright Ⓒ 2023 Mirametrics, Inc. All
Rights Reserved.
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