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displayColorPatch

Display measured and reference color as color patches

Description

example

displayColorPatch(colorTable) displays measured and reference colors, colorTable, for color patch regions of interest (ROIs) in a test chart. The measured color values are displayed as squares surrounded by a thick boundary of the corresponding reference color.

example

displayColorPatch(colorTable,Name,Value) displays measured color values with additional name-value arguments to control aspects of the display.

Examples

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Read an image of an X-Rite® ColorChecker® chart into the workspace.

I = imread('colorCheckerTestImage.jpg');

Create a colorChecker object, then display the chart with ROI annotations.

chart = colorChecker(I);
displayChart(chart,'displayRegistrationPoints',false)

Figure Color checker test chart contains an axes object. The axes object contains 25 objects of type image, text.

Measure the color in each color patch ROI.

colorTable = measureColor(chart);

On a color patch diagram, display the measured and reference colors and the color error (ΔE).

displayColorPatch(colorTable)

Figure Visual Color Comparison contains an axes object. The axes object contains 25 objects of type image, text.

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

Read an image of an eSFR chart into the workspace.

I = imread('eSFRTestImage.jpg');

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

chart = esfrChart(I);
displayChart(chart,'displayEdgeROIs',false, ...
    'displayGrayROIs',false,'displayRegistrationPoints',false)

Figure eSFR test chart contains an axes object. The axes object contains 17 objects of type image, text.

Measure the color in all color patch ROIs.

colorTable = measureColor(chart);

Display the color accuracy measurements without the ROI index overlay. Each square color patch is the measured color, and the thick surrounding border is the reference color for that ROI. The color accuracy measurement is displayed as Delta_E, the Euclidean distance between measured and reference colors in CIE 1976 L*a*b* color space. More accurate colors have a smaller Delta_E.

displayColorPatch(colorTable,'displayROIIndex',false)

Figure Visual Color Comparison contains an axes object. The axes object contains 17 objects of type image, text.

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:

VariableDescription
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.
Measured_R

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.

Measured_G

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

Measured_B

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

Reference_L

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

Reference_a

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

Reference_b

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.

Name-Value 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 quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: 'displayROIIndex',false turns off the display of the ROI indices.

Display ROI index labels, specified as the comma-separated pair consisting of 'displayROIIndex' and a numeric or logical 1 (true) or 0 (false). When displayROIIndex is true, then displayColorPatch overlays color patch ROI index labels on the displayed color patches. The indices match the ROI numbers displayed by displayChart.

Display color error ("delta E") values, specified as the comma-separated pair consisting of 'displayDeltaE' and a numeric or logical 1 (true) or 0 (false). When displayDeltaE is true, displayColorPatch overlays the color error values on the displayed color patches.

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 displayColorPatch.

Tips

  • To obtain a color table of the correct format from an esfrChart or colorChecker object, use the measureColor function. You can also create your own color table containing measured and reference colors for an arbitrary number of color ROIs.

  • The reference L*a*b* values of a colorTable measured from a colorChecker object are for the "After November 2014" version of the X-Rite® ColorChecker® chart. The white point of the reference values is the CIE standard illuminant D50.

Introduced in R2017b