Blackfly - CYLOD

Point Grey Blackfly Technical Reference
8 Blackfly Attributes
8.16 Color Model Attributes
The following features are only available on color Blackfly models.
8.16.1 White Balance
The Blackfly supports white balance adjustment, which is a system of color correction to account for differing lighting
conditions. Adjusting white balance by modifying the relative gain of R, G and B in an image enables white areas to
look "whiter". Taking some subset of the target image and looking at the relative red to green and blue to green
response, the objective is to scale the red and blue channels so that the response is 1:1:1.
The user can adjust the red and blue values. Both values specify relative gain, with a value that is half the maximum
value being a relative gain of zero.
White Balance has two states:
State
Off
On/Manual
Description
The same gain is applied to all pixels in the Bayer tiling.
The Red value is applied to the red pixels of the Bayer tiling and the Blue value is applied to the blue
pixels of the Bayer tiling.
The following table illustrates the default gain settings for most cameras.
Red
Blue
Black and White 32 32
Color 1023 1023
The camera can also implement Continuous and Once white balance. One use of Continuous and Once white balance
is to obtain a similar color balance between cameras that are slightly different from each other. In theory, if different
cameras are pointed at the same scene, using Continuous and Once will result in a similar color balance between the
cameras.
Once only attempts to automatically adjust white balance for a set period of time before stopping. It uses a “white
detection” algorithm that looks for “whitish” pixels in the raw Bayer image data. Once adjusts the white balance for a
specific number of iterations; if it cannot locate any whitish pixels, it will gradually look at the whitest objects in the
scene and try to work off them. It will continue this until has completed its finite set of iterations.
Continuous is continually adjusting white balance. It differs from Once in that it works almost solely off the whitest
objects in the scene.
The white balance of the camera before using Continuous and Once must
already be relatively close; that is, if Red is set to 0 and Blue is at maximum (two
extremes), Continuous and Once will not function as expected. However, if the
camera is already close to being color balanced, then Continuous and Once will
function properly.
Revised 12/13/2012
Copyright ©2012 Point Grey Research Inc.
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