ABB PickMaster Twin - PowerPac Applications Manual page 291

The result of the color filter is a grayscale image in which certain colors have been
accentuated or attenuated according to the filter settings. The object recognition
tools (Blob/PatMax) operate on this grayscale image.
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Prerequisites
The camera must be a color camera.
The color video format must be configured for the camera.
The Cognex vision license must contain the color tool option.
Calibrating the camera's white balance
A camera is delivered with default settings. These include three parameters which
represent the white balance of the camera. Depending on the light source, the
image can get an undesired color tone. Different light sources emit light of different
temperatures (color content) and the camera needs to be color calibrated in order
to compensate for this light.
The basic concept is to present the camera with a gray scene, that is a scene that
has equal contents of red, green, and blue. The most accurate method is to take
a sheet of white paper and adjust the light settings of the camera in order to make
the scene appear gray.
Use this procedure to calibrate the white balance for the camera.
Application manual - PickMaster® Twin - PowerPac
3HAC064218-001 Revision: B
An image acquired with a color camera.
The same scene acquired with a monochrome camera.
The color image after having passed through a filter which is set to extract green.
This is the image that will be used by PatMax/Blob.
1 In the line view, right-click on the camera and select Edit.
The Camera Configuration dialog is opened
2 Place a white sheet of paper under the camera. The sheet must cover the
whole field of view.
3 Adjust the light settings (aperture or exposure time) to make the scene appear
mid-gray. The number of saturated pixels (completely black or white) should
be kept to a minimum.
4 Press Calculate. This will calculate the white balance calibration parameters.
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4 Working with PickMaster PowerPac
4.4 Using color vision
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