Tech Note
Example 1 - Maximum Dynamic Range (no overlap)
To create an image that spans the maximum range of light intensities, use shutter settings to calibrate the 2 sensors so that Sensor B = Sensor A * 1024. In other words, the light needed to generate 100 counts from Sen- sor B is 1024 times the light needed to create 100 counts from Sensor A.
For example, if Sensor A is operating with the shutter off (1/30 sec.), Sensor B would need to be set as close as possible to 1/30720 sec. using the camera’s
Now, create a fused image by applying a post processing routine that uses output from Sensor A when it is below saturation and from Sensor B when Sensor A is saturated. A simplified representation of this routine could be the Boolean expression:
if (pixel B < 1){ pixel_out = pixel A
}else{
pixel_out = pixel B * 1024
}
This approach uses Sensor B to add 10 more bits of dynamic range to the image, albeit at a lower precision than the lower
FIGURE 3 – Maximum dynamic range calibration
One issue with any high dynamic range approach is that it is hard to display or print such an image. Besides the challenge of handling the data in a Microsoft OS, most displays and/or printers do not have this much dynamic range and will diminish your good work. Typical computer monitors today feature contrast ratios on the order of 1,000 to 1, enabling them to approximate
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