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Plot color reproduction on chromaticity diagram





plotChromaticity(colorTable) plots on a chromaticity diagram the measured and reference colors, colorTable, for color patch regions of interest (ROIs) in a test chart.

plotChromaticity(colorTable,Name,Value) plots measured and reference colors with additional parameters to control aspects of the display.

plotChromaticity plots an empty chromaticity diagram.

plotChromaticity(Name,Value) plots an empty chromaticity diagram with additional parameter 'Parent' that specifies a handle of a parent axes of the plot object.


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This example shows how to display the chromaticity diagram from measurements of color accuracy on an Imatest® eSFR chart.

Read an image of an eSFR chart into the workspace. Linearize the image.

I = imread('eSFRTestImage.jpg');
I_lin = rgb2lin(I);

Create an esfrChart object. Display the chart, highlighting the 16 color patches.

chart = esfrChart(I_lin);

Measure the color in all color patch ROIs.

colorTable = measureColor(chart);

Plot the measured and reference colors in the CIE 1976 L*a*b* color space on a chromaticity diagram. Red circles indicate the reference color and green circles indicate the measured color of each color patch. The chromaticity diagram does not portray the brightness of color.


Input Arguments

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Color values in each color patch, specified as an m-by-8 color table, where m is the number of patches. The eight columns represent these variables:

ROIIndex of the sampled ROI. The value of ROI is an integer in the range [1, 16]. The indices match the ROI numbers displayed by displayChart.

Mean value of red channel pixels in an ROI. Measured_R is a scalar of the same data type as chart.Image, which can be of type single, double, uint8, or uint16.


Mean value of green channel pixels in an ROI. Measured_G is a scalar of the same data type as chart.Image.


Mean value of blue channel pixels in an ROI. Measured_B is a scalar of the same data type as chart.Image.


Reference L* value corresponding to the ROI. Reference_L is a scalar of type double.


Reference a* value corresponding to the ROI. Reference_a is a scalar of type double.


Reference b* value corresponding to the ROI. Reference_b is a scalar of type double.

Delta_EEuclidean color distance between the measured and reference color values, as outlined in CIE 1976.

To obtain a color table, use the measureColor function.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: plotChromaticity(myColorTable,'displayROIIndex',false) turns off the display of the ROI indices on the chromaticity diagram.

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Display ROI index labels, specified as the comma-separated pair consisting of 'displayROIIndex' and true or false. When displayROIIndex is true, then plotChromaticity overlays color patch ROI index labels on the chromaticity diagram. The indices match the ROI numbers displayed by displayChart.

Data Types: logical

Axes handle of the displayed image object, specified as the comma-separated pair consisting of 'Parent' and an axes handle. Parent specifies the parent of the image object created by plotChromaticity.

See Also


Using Objects

Introduced in R2017b

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