Analyses - Color Image

Navigation: Analyses Commands > Color Image

Color Image

Page Contents

Description

Navigation

Controls

Application Notes

•Data display and export

•Color Correlated Temperature

•Image artifact diagnostic tool

Related Topics

Description

The Color Image analysis feature calculates the XYZ chromaticity coordinates (CIE 1931) for each pixel of the selected analysis surface and then converts the chromaticity coordinates to RGB values for display in the Chart Viewer. Conversion from XYZ to RGB proceeds in the following way:

1.		Determine the maximum Y tristimulus value in the dataset
2.		Scale each tristimulus value by the factor: brightness/Y_max
3.		Convert from scaled XYZ tristimulus to RGB using the sRGB matrix: [ 3.2406 -1.5372 -0.4986 ] [-0.9689 1.8758 0.0415 ] [ 0.0557 -0.2040 1.0570 ]
4.		R,G,B values outside of the range from 0 to 1.0 are considered "out of gamut" and clamped at either 0 or 1.0
5.		Apply gamma correction (gamma = 2.2) to the RGB pixel values (ex. R = R^{1 / 2.2})

The Color Image chart view has four panes; an RGB spatial map on the analysis surface, two cross-sectional profiles, and a chromaticity diagram. As the cursor is moved in the spatial map a cursor in the chromaticity diagram indicates the XY chromaticity coordinate corresponding to the current pixel.

Navigation

This command can be accessed in the following ways:

•Menu > Analysis > Color Image

•Toolbar button:

Controls

Control	Inputs / Description	Defaults
Use This Analysis Surface
Use This Analysis Surface	Currently selected analysis surface	First surface in list
List of Available Analysis Surfaces
List of Available Analysis Surfaces	Lists the available analysis planes for use as the ray filter.	Valid analysis surfaces
Pre-Analysis Ray Operations
Delete old rays and recreate all active sources	If checked, existing rays are deleted, and new rays are created before the analysis proceeds.	Unchecked if rays exist. Checked if no rays exist.
Raytrace all active rays	If checked, any existing rays are raytraced before the analysis is performed.	Unchecked if rays exist. Checked if no rays exist.
Plot the rays as they are being raytraced	If checked the rays will be drawn to the 3D view when traced.	Unchecked
Post-Analysis Operations
Create Analysis Results Node (ARN)	Adds an Analysis Results Node (ARN) to the Analysis Results folder on the object tree. The ARN being created stores the results of, and information about, the analysis being performed.	Unchecked
Name Prefix	The name of the ARN on the tree will be formed by combining this name prefix with an automatically generated numeric value, ensuring that the resulting ARN has a unique name string.	ColorImageXYZ

OK	Perform analysis and close dialog box.
Cancel	Discard analysis and close dialog box.
Help	Displays this help article

Application Notes

Data display and export

The data can be displayed in the chart viewer as RGB, Greyscale, Luminosity, or as one of the three RGB components by right clicking in the chart and selecting one of the following options:

•Show Color (RGB)

•Show Greyscale

•Show Red Component

•Show Green Component

•Show Blue Component

•Show Luminosity

Additionally, Color Image data can be written to file or read from file by right clicking in the chart and selecting Save Image (XYZ) to File or Read Image (XYZ) from File.

Color Correlated Temperature (CCT)

On running this analysis the output window features an average, and weighted average Temperature value in Kelvin for Color Correlated Temperature (CCT). In the weighted average calculation each pixel is weighted by its luminance. Users should be aware that any estimate of the temperature of a particular color image is only generally accurate if the result is near the Plankian Locus. Evaluating the color temperature of a result far from the Plankian Locus should be avoided.

Image Artifact Diagnostic Tool

If a raytrace has been performed using the Advanced Raytrace option with ray paths enabled, contributing raypath information for a particular region of interest can be reported directly from the chart view for an incoherent spatial analysis or analyses using a Directional Analysis Entity. This feature can be executed by holding down the ALT keyboard button while using the mouse to select a region of the main chart view (turn of "perspective view" using the right mouse button menu option). This procedure is outlined in the following example:

1.Perform an Advanced Raytrace (ray paths on).

2.Perform an incoherent spatial or directional analysis (irradiance, illuminance, color image, position spots diagram).

3.In the main chart view hold ALT while using the mouse to select a region of interest (shown in red).

4.Resulting path information is printed to the output window.

The image artifact diagnostic tool will print the following information to the output window:

•Analysis surface used

•Selected region x-min, x-max, y-min and y-max

•Path number, path power and ray count for each contributing ray path (up to the first 30 paths, sorted by power)

•Remaining path count and total power for paths not listed in the output window