Exam B-DYNRNG

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Exam 6.0.3[edit]

B-DYNRNG.jpg

The following curve shows the log compression and dynamic range reduction of the Exam software. The parameters that determine the shape of the curve are described here.

LogCompress.jpg

The DR Reject Sum determines the minimum level of the signal for which there will be a nonzero intensity in the image. All signals below this level are considered noise and mapped to the zero intensity. The DR Log Sum determines the range of signals for the logarithmic portion of the curve, and the DR Linear determines the range of signals for the linear portion of the curve. The DR Pivot Out determines the intensity level in the output gray scale image below which a logarithmic compression is used, and above which a linear mapping is used. A DR Pivot Out of 255 essentially eliminates the linear portion of the curve, and a level of 0 eliminates the logarithmic portion.

  • DR Reject Sum
  • DR Log Sum
  • DR Linear
  • DR Pivot Out

In order to account for differences in the A-mode data resulting from the hardware versions, calibration offset parameters are used. The DR Log Sum is thus the sum of DR Log, which is the hardware independent dynamic range for the logarithmic portion of the curve chosen by the user, plus a hardware specific offset determined by the factory which is in DR Log Offset. Similarly, for the noise rejection level, the DR Reject Sum is the sum of DR Reject, which could be the hardware independent range chosen by the user, plus DR Reject Offset, the hardware specific calibration offset added by the factory.

  • DR Log
  • DR Log Offset
  • DR Reject
  • DR Reject Offset