Metrics, Tolerances & Reporting

Metrics

Metrics are the different forms of measurement data which Maxwell calculates for your tracks. Examples of some Maxwell metrics are:

• Average delta E

• Maximum delta E

• Minimum delta E

• Media delta E

• Standard Deviation

• Average delta E - worst 10%

• Average delta E - best 90%

Maxwell will automatically calculate and retain the results for these seven metrics with each measurement it collects - even if they are not specified in your Metric Details pane.

Some metrics of interest:

• Media delta E tracks the white point only, so you can see if your media is changing (and can also be an indication of your measurement repeatability.)

• Standard Deviation is a measure of how widely distributed the measurements are from the average. It is worthwhile checking standard deviation on measurement data, since average delta E by itself will not show you how widely varied those measurements are.

• Worst 10% / Best 90% reports on the average of the worst 10% of patches or the average of the best 90%.

• Average/Max Delta H returns the average/maximum of the delta Hue - how far apart is the hue component only.

• Average/Max Delta C returns the average/maximum of the delta Chroma - the color saturation component.

• Maximum Delta L returns the maximum difference in lightness.

• G7 Metrics return the result of pass/fail of the G7 specification, according to the indicated compliance level (G7 Grayscale, Targeted, or ColorSpace).

Creating Metrics

Metrics are part of a Reference Set which is found in the top tab marked REFERENCES.

A reference set will contain the measurement file you are using as a color aim (sometimes known as a reference file), and the Metrics that are associated with this Reference Set.

Click + Create Metric

Click the + Create Metric button to open up the Metric dialog.

Many users find it helpful to create at least an "average deltaE" metric and a "maximum deltaE" metric.

NOTE: At least one metric is required in order to view a trend report.

• Give the metric an identifying name (Metric Name)

• Select what kind of metric it is (Metric Type)

• The G7 fields are for metrics relating to the G7 specification

• Choose calculation method under "units" (deltaE 76 or dE 2000)

(The CIELAB2000 Color Difference Equation is a ellipsoidal color difference scale similar to CMC.)

• Upper Failure Level determines the threshold at which a measurement will fail. This is like a red traffic light requiring your production to stop until a problem is corrected. A Notifier is triggered for this track (when a notifier is enabled.) For example, a value of 6 on a 'Maximum deltaE' metric for a display track would trigger an email notifier when a new profile is uploaded which contains any colors greater than 6 delta E from the color aim.

• The Upper Warning Level will give a “yellow light” kind of warning. This is to indicate that the measurement does not fall outside of your critical tolerances, but is a warning that the color is getting close to failure.

• Patch Device Values: It is possible to create a metric that tracks specific device values. For example, if you wish to track the results of measuring the 50, 40, 40, 0 CMYK patch in a target, specify that here.

  • Enter the RGB or CMYK values in order to engage this feature.

  • Each value must be separated by a comma

  • Continue giving the metric a name, choosing a metric type, and choose the correct units as usual

  • For individual device values, it makes no difference what metric type is used since only one color is involved. (We recommend using Maximum delta E.)

  "-1" is the default. This disables the use of individual patch values.

• Patch Selector Colorset: It is also possible to choose a subset of colors of a larger target for use as a metric. For example you could choose to track how well a printer is able to consistently print flesh tones.

  • Upload a measurement set consisting of the colors you wish included in the subset. (This should be in the CGATS format with either RGB or CMYK device values for each color.)

    • Go into the Color Set Details of this new measurement set and choose an option under Patch Selector Set:

  • PatchCode - identifies the list of colors by the numerical PatchCode.

  • Names - identifies the list of colors by the name of the uploaded measurement set.

  • In the "Metric Details" pane, choose the appropriate patch set that appears in the drop down box under "Patch Selector ColorSet."

  The default is "(all patches)."

• Plot color: Maxwell will automatically assign contrasting colors to the actual trend line depending on how many metrics you have listed.

  If desired, a specific color can be assigned to this metric in the trend line by using this field.

  • Enter a specific red, green, blue number, or a specific hexadecimal number in order to have a specific color show up in the trend line plot for this metric. For example, if you are trending a specific CMYK patch with a single metric, you may wish to choose an RGB equivalent color to represent that in the plot of the trend line.

• Click Create button when done.

Note that Maxwell has many powerful features, and not every feature needs to be used on every printing system.