Use the Calibration Window to set up calibration tables. Because the calibration is size-specific, you must calibrate with the same setup that you are using to collect images (e.g., if you are imaging 512 x 512 on 60x, you must calibrate with that setup.)
Open Calibration by choosing Calibration | Make on the Resolve3D window.
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Field |
Description |
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Number of dark images |
Specifies the number of images to average when taking Dark Current exposures. Increasing the number of dark images may reduce the noise at the expense of calibration time. |
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Dark exposure |
Specifies the exposure time to use when taking Dark Current exposures. This should be the same as the Longest exposure in order to best capture 'hot pixel' information when imaging in the normal exposure range for the channel being calibrated. |
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Shortest exposure |
Specifies the shortest exposure to use when imaging the calibration slide. |
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Longest exposure |
Specifies the longest exposure time to use when imaging the calibration slide. This time should be at least as long as the longest exposure time that is used when imaging the channel to which this calibration is to be applied. To determine an optimal value, find the exposure time that achieves a maximum intensity (3800-4000). |
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Number of exposures |
The number of exposures to use when imaging the calibration slide to determine gains and offsets. The number of exposures can be reduced to decrease calibration time at the expense of some increased noise in the calibration. |
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Use the Dark Current section to view the statistics and intensity histogram of the CCD camera dark current. In the absence of light, the CCD camera produces an image that is referred to as the dark current image. The range of values in this image are an indication of the camera's readout noise.
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Field |
Description |
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Min |
The minimum intensity in the dark current image. This value should never be zero. |
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Max |
The maximum intensity of the dark current image. Depending upon the temperature of the CCD chip, this value may be a function of the exposure time. For example, the Kodak KAF series chips contains "hot pixels" that appear in the image as non-linear functions of exposure time. |
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Mean |
The average dark current intensity. |
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SD |
The standard deviation about the mean of the dark current intensity. |
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Slope shows the statistics and intensity histogram of the slope of the CCD response to light, as determined by linear regression. The value of the slope is adjusted so that the mean value of the slope is 1. Pixels with slope < 1 are less sensitive than average, whereas pixels with slope > 1 are more sensitive.
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Field |
Description |
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Min |
The minimum slope value. |
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Max |
The maximum slope value. |
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Mean |
The average slope value. This should be very close to 1. |
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SD |
The standard deviation about the mean of the slope image. |
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Offset shows the statistics and intensity histogram of the offset of the CCD response to light, as determined by linear regression. This is also referred to as the "intercept" of the response curve. The offset and dark current are not exactly the same.
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Field |
Description |
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Min |
The minimum offset value. |
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Max |
The maximum offset value. |
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Mean |
The average offset value. This should be nearly identical to the mean of the dark current. |
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SD |
The standard deviation about the mean of the offset image. |
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Correlation shows the statistics and intensity histogram of the correlation coefficients resulting from linear regression. In principle, the values can range between zero and one. Zero means that the response is completely non-linear. One means that the response is perfectly linear (the closer the values are to one, the better). In practice, CCD chips are very linear and most pixels respond linearly with a correlation coefficient of nearly one.
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Field |
Description |
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Min |
The minimum correlation value. This is often better than 0.99980. |
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Max |
The maximum correlation value. In some situations, the maximum is actually reported as 1.0000 (Although this indicates a perfect response, it's actually a result of rounding the number up to 1.) |
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Mean |
The average value of the correlation coefficient. |
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SD |
The standard deviation about the mean of the correlation image. |
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Button |
Description |
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Done |
Quits the Calibration tool. |
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Calibrate |
Performs a calibration with the specified options. |
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Save |
Saves the calibration table. (When you save the table, you are prompted to name it.) |
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