Cheetah KAC Camera User Manual | Camera Link (CLF) Interface
October 1, 2019
Page
103
of
135
Rev 7.2
Percentage of Output
Pixel Data
100%
Bright Pixel Data
51%
50%
Dark Pixel Data
0%
Table 22: Example of output partitioning for two intensity slopes.
Assuming 10-bit digitization, dark pixel data values range from 0 to 512 counts (50% of
the output) and bright pixel data values range from 513 to 1024 counts (51% to 100% of
the output). Keep in mind that the camera captures bright pixel data with a much shorter
exposure time. For example, suppose you select a bright pixel exposure time that is 10%
of the overall exposure time. In this case, a pixel with a value of 612 counts resides in the
bright pixel data partition and represents 100 counts (612 – 512) taken with an exposure
that is 10% of the total exposure. The camera collects these 100 counts of signal with
1/10
th
of the exposure time of the dark pixels. Therefore, the 100 counts are 10x brighter
than 100 counts of signal collected in the dark pixel partition.
The following table is just one example of how the output can be partitioned into four
separate exposure zones. To reinforce the concept of output partitioning, suppose the
user selects the partitioning in the following table with 10-bit digitization and selects the
total exposure to be 50ms (Dark pixels), the Bright pixel exposure to be 5ms, the Very
Bright pixel exposure to be 0.5ms and the Ultra-Bright pixel exposure to be 0.05ms. In this
example, Dark pixels with a 50ms exposure are contained between 0 to 300 output counts
(30% of output), Bright pixel data with a 5ms exposure have counts between 301 to 600,
Very Bright pixel data with 0.5ms exposures have counts between 601 to 800 and Ultra-
Bright pixel data with 0.05ms exposures have counts between 800 to 1000. A single count
in the Ultra-Bright pixel data region represents signal that is 1,000x higher intensity (50ms
/ 0.05ms) than a single count in the Dark pixel data region.
