User`s manual

Standard Features AW00049313000
194 Basler runner
11.7 Shading Correction
In theory, when a digital camera captures an image of a uniform object, the pixel values output from
the camera should be uniform. In practice, however, variations in optics and lighting and small
variations in the sensor’s performance can cause the camera output to be non-uniform even when
it is capturing images of a uniform object. The camera is equipped with a gain shading correction
feature that allows it to correct acquired images for variations caused by optics, lighting, and sensor
variations.
The gain shading feature works by applying a multiplier to each pixel value in the acquired lines. To
perform gain shading correction, the camera uses a file containing a table of multipliers. The table
must contain a multiplier for each pixel in the camera’s sensor. A file containing a complete set of
multipliers is commonly referred to as a "shading set". In order to use gain shading, the user must
create at least one shading set file and upload it to the camera. The camera can hold two complete
user-created shading set files, which are designated as User Shading Set 1 and User Shading
Set 2. When the user shading set files are uploaded to the camera, they are stored in the camera’s
non-volatile memory and are not lost if the camera power is switched off. Uploading a User Shading
Set 1 file or a User Shading Set 2 file to the camera will overwrite any previously stored corres-
ponding user shading set.
The camera also contains a Default Shading Set, which is a factory-created shading set file that can
not be overwritten.
Any time you make a change to the optics or lighting or if you change the camera’s
gain settings or exposure mode, you must create new shading set files. Using out
of date shading set files can result in poor image quality.
When you create a shading set file, correction values must be created for all of the
pixels in the sensor’s line(s) regardless of how you plan to use the camera during
normal operation.