Metric

R2026b

Optical metric function

Since R2026b

Description

Add-On Required: This feature requires the Optical Design and Simulation Library for Image Processing Toolbox add-on.

Metric functions for analysis of optical system.

Creation

Create a collection of optical metric functions using the opticalMeritFunction function. The opticalMeritFunction function creates a 1-by-n array of Metric objects. Each element in the array is an object of one of these types of metric function classes.

• SpotRMS

• CustomMetric

Examples

Evaluate Optical Merit Function Using Custom Metrics with Residual Score

Import an optical system into the workspace.

opsys = zmximport("PhotographicLens.zmx");

Create an empty optical merit function.

meritFcn = opticalMeritFunction;

Add a custom metric function that returns only the residual score. The custom function maxDistortionMetric is defined at the end of this example.

meritFcn = addCustomMetric(meritFcn,@maxDistortionMetric,Target=2.0,Name="Max Distortion (%)")

meritFcn = 
  opticalMeritFunction with properties:

         Metrics: [1×1 optics.metric.CustomMetric]
         Weights: 1
    MetricsTable: [1×3 table]

Evaluate the merit function for the optical system.

[score,rawMetricValues] = evaluate(meritFcn,opsys)

score = 
1.8706

rawMetricValues = 
1.8706

Custom Function

The maxDistortionMetric custom function measures the strongest lens distortion across the field, and computes how far it is from the desired target. If the target value is 0, the function returns the greatest distortion magnitude. Otherwise, it returns a normalized nonnegative score indicating how much that distortion exceeds the target.

function score = maxDistortionMetric(opsys,target)
    distResult = lensDistortion(opsys);
    maxDist = max(abs(distResult.Distortion),[],"all");
    if target(1) == 0
        score = maxDist;
    else
        score = max(0,(maxDist-target(1))/target(1));
    end
end

Evaluate Optical Merit Function Using Custom Metrics with Residual and Raw Scores

Import an optical system into the workspace.

opsys = zmximport("PhotographicLens.zmx");

Create an empty optical merit function.

meritFcn = opticalMeritFunction;

Add a custom metric function that returns the residual and raw score. The custom function chromaticMetric is defined at the end of this example.

meritFcn = addCustomMetric(meritFcn,@chromaticMetric,Target=[0.001 0.005],Name="Lateral Chromatic Aberration")

meritFcn = 
  opticalMeritFunction with properties:

         Metrics: [1×1 optics.metric.CustomMetric]
         Weights: 1
    MetricsTable: [1×3 table]

Evaluate the merit function for the optical system.

[score,rawMetricValues] = evaluate(meritFcn,opsys)

score = 
1.3402

rawMetricValues = 
0.0117

Custom Function

The chromaticMetric custom function measures the strongest lateral chromatic aberration across the field, and penalizes deviations outside a desired limit or range. The function computes the maximum lateral chromatic aberration of the optical system as the raw metric value, and compares this value to a target range to compute the residual score. If the target is a single value, it returns a normalized score of how much the raw metric exceeds that value (0, if within the limit). If the target is a range, the score is 0 if the metric lies within the range. Otherwise, the function returns a normalized score of how far the metric is from the nearest boundary.

function [residualScore, metricValue] = chromaticMetric(opsys,target)
    caResult = chromaticAberration(opsys);
    % metricValue: the physically meaningful quantity (lateral chromatic aberration)
    metricValue = max(abs(caResult.Lateral.Aberration),[],"all");
    % residualScore: unitless penalty relative to target
    if target(1)==target(2)
        if target(1) == 0
            residualScore = metricValue;
        else
            residualScore = max(0,(metricValue-target(1))/target(1));
        end
    else
        if metricValue >= target(1) && metricValue <= target(2)
            residualScore = 0;
        else
            diffs = abs(target - metricValue);
            [~,idx] = min(diffs);
            residualScore = abs(metricValue-target(idx))/target(idx);
        end
    end
end

Version History

Introduced in R2026b