A Bit Less Confusing
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A Bit Less Confusing
When it comes to infrared imager specifications, the term “bit” is frequently used to describe detectors, file sizes, and display screens. In this week’s Tip, we attempt to make this term a bit less confusing.
Bit is a common term in the computer industry used to describe quantities of data. One bit of data equals two levels of information; the number of data levels doubles with each successive increase in the number of bits. The chart below shows the relationship between bits and data levels.
|
Bits
|
Data Levels
|
1
|
2
|
2
|
4
|
3
|
8
|
4 |
16
|
5
|
32
|
6
|
64
|
7
|
128
|
8
|
256
|
9
|
512
|
10
|
1,024
|
11
|
2,048
|
12
|
4,096
|
13
|
8,192
|
14
|
16,384
|
15
|
32,768
|
16
|
65,536
|
For thermal imagers, the term bit is used to describe detector outputs, stored image sizes, and display screens. Modern imager detectors are usually specified at 12 to 16 bits (4096 to 65,536 levels of data). In general, either a 12 or 14 bit detector is sufficient for good image quality and allows stored images to be post processed.
Many modern thermal imagers are capable of digitally storing image files to removable media such as a PC card and/or the imager’s internal memory. Typical file storage is 12 bits or 4096 levels of data. Depending upon imager capabilities, stored image files can be recalled and post processed. In particular, level and gain settings may be adjusted within the imager or in manufacturer-supplied software. When stored thermal images are recalled, they are displayed on the imager’s monitor at 8 bits or 256 levels of color or grayscale.
