User manual

Phantom Help File348

9 Functional Descriptions

The purpose of this module is to specify the functionality of various features and options associated

with a Phantom camera, and all related the Phantom Camera Control applications.

9.1 Black Reference/Current Session Reference Adjustments

After a camera comes up to its operating temperature, or after changing camera settings, calibrating

the camera to a black reference will help ensure you get the best possible images from your Phantom

camera.

A black reference measures the value of each pixel with no light on it (black) and stores the values in

a calibration file (called an “STG”). Later, the camera firmware can use those values to ensure that all

sensor pixels are providing the same value for equivalent amounts of light.

There are two types of black references on Phantom cameras, they are a:

Current Session Reference (CSR)

Current Session Reference” is a calibration procedure similar to Black Reference except the fact

that it computes the pixel offsets only on the part of the sensor that is the next greater value after

the resolution set in acquisition parameters.

This way, the offsets can be computed for any frame rate, exposure or resolution, giving a more

precise compensation of the pixel errors, dependent on the acquiring parameters and on

temperature. Of course, if the acquisition parameters change, you may get worse results than

using the universal Black Reference procedure. The CSR is applied correctly only for the set of

acquisition parameters used when this reference was calculated.

This black reference is available for any image resolution. When the acquisition parameters,

(resolution, frame rate, exposure time), have certain values, (for example, the frame rate is high

or the set of values forces the camera performances), it is recommended to do a CSR for that

specific set of parameters in order to obtain a better image.

After executing a CSR, if you change the acquisition parameters, the calibration calculated during

the Current Session Reference will apply partially correct on the new setup. For example, if you

use a bigger resolution than the one used when the CSR was calculated, the CSR adjustments

will be applied only on that part of image and for the rest of the image the black reference

calibration calculated in the Options window will be used.

The CSR calibration can be saved in a .STG file, for example:

1009_res256x256_rate80_exp12000_edr0..STG.

Thus, you can easily choose a .STG according to the acquisition you are currently using. This

.STG file will be opened automatically at the program restart if you rename it by the serial number

of the camera: 1009.STG in this example.