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Stray light (flare) documentation pages

IntroductionIntro to stray light testing and normalized stray lightOutputs from Imatest stray light analysis | History

Background | Examples of stray lightRoot Causes | Test overview | Test factors | Test ConsiderationsGlossary

Calculations | Metric image calculationsNormalization methodsLight source mask methods

Instructions | High-level Imatest analysis instructions (Master and IT) | Computing normalized stray light with Imatest | Motorized Gimbal instructions

Settings | Settings list and INI keys/values | Configuration file input


Page Contents

This page provides a description of the analysis channel options.

Channel Groups

Channel groups describe which groups of channels to analyze.

Name# Input ChannelsDescription INI Value
AutomaticAnyAutomatically choose what analysis channels to use based on the provided image(s).
  • If input data has 1 channel → Monochrome
  • Otherwise → Each Channel
Each ChannelAnyAnalyze each input channel1
RGB3Analyze each of the three provided channels as red, green, blue.2
Monochrome1Analyze the single provided channel as monochrome.3
MeanAnyAnalyze the mean of all provided channels.4
Luminance3Analyze the luminance channel. Data are assumed to be 3 channel in (red, green, blue) order.5
RGB + Luminance3Analyze the three (red, green, blue) channels and the computed luminance channel.6

Luminance Channels

The following weights are available for computing a luminance channel via 

\(\text{Luminance} = w_{red}\cdot \text{Red} + w_{green} \cdot \text{Green} + w_{blue} \cdot \text{Blue} \)

NameRedGreenBlueINI Value
IEC 61966-2-10.2126 0.71520.07221
ITU-R BT.601-70.2990.5870.1142


Normalization Factor Analysis Channel

For Direct Reference Image and/or Lambertian Reference Image normalization, if the Channel Group is Luminance or RGB + Luminance, then the Luminance channel of the reference image is used. Otherwise the Mean of the reference image is used.

Coloring and Data Labeling

The choice of analysis channels controls how the data are labeled and colored in plots and results.

Image/Settings Mismatches

Imatest will not run if there is a mismatch between the selected settings and the provided image (e.g., trying to analyze a monochrome image as RGB or Luminance, each of which requires three input channels).