Cheetah Python Camera with USB3 Interface
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User Manual
December 5, 2017
Page
71
of
78
Rev 1.0
5.11 Test Image Patterns
5.11.1 Test Image Patterns
The camera can output several test images to verify the camera’s general performance
and connectivity to the computer. This ensures that all the major modules in the
hardware are working properly and the connection between the computer and camera is
synchronized, that is, the image framing, output mode, communication rate, and so on
are properly configured. Note that the test image patterns do not exercise and verify the
image sensor functionality. The following test images are available:
Patterns
Description
H Ramp Still
Displays a stationary horizontal ramp image.
V Ramp Still
Displays a stationary vertical ramp image.
H Ramp Move
Displays a moving horizontal ramp image.
V Ramp Move
Displays a moving vertical ramp image.
Cross-hairs
Displays cross-hair pattern in center of image over a superimposed live image
(cross-hair thickness is 2 pixels).
Table 8: Test patterns.
5.12 White Balance and Color Conversion
5.12.1 White Balance Correction
The color representation in the image depends on the spectral content of the light source.
Cheetah cameras have a built-in algorithm to compensate for this effect. With white
balance correction enabled, the camera collects the data for all of the image sensors R, G,
and B pixels, analyzes it, and adjusts the color gain coefficients for each color pixel to
properly proportion the colors and make white objects appear white. The algorithm
collects data from the entire image and can work in the following modes: Off, Once, AWB
Tracking, and Manual.
AWB Mode
Description
Off
No white balance correction performed.
Once
Camera analyzes one image frame, calculates only one set of coefficients, and
corrects all subsequent frames with this set of coefficients.
Image a grey or white target over the entire field of view of the camera using
the intended illumination source for best white balance coefficients.
AWB Tracking
Camera analyzes every frame, derives a set of correction coefficients for each
frame, and applies them to the next frame.
Manual
Camera uses the correction coefficients you enter.
Table 9: Automatic white balance modes.
