ΔE Calculation Filter Reference
The ΔE calculation filter calculates the CIE ΔE 2000 between the L*a*b* values of the input against one or more reference values.
Category |
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Node |
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Parameters |
Mode: Whether the reference values are specified manually (Manual) or whether they are provided by the averages of the assigned groups (By Group) L*: The reference L* value in manual mode a*: The reference a* value in manual mode b*: The reference b* value in manual mode |
Inputs |
Color: the input L*a*b* values |
Outputs |
Output: the ΔE values calculated against the reference values. In Manual mode this will have exactly one channel; in By Group mode this will have as many channels as there are groups in the model (in the order of the group list of the model); if a group has no assigned data the entire channel will be NaN for that group. |
Effect of the Filter
In Manual mode the user may specify L*, a*, and b* values in the parameters that will be used as the reference for the filter. The input must be CIE L*a*b* values, which can be obtained via the Color Determination Filter. The output will have a single channel for each pixel, and will contain the ΔE value for each pixel, calculated according to the CIE 2000 standard.
Take, for example, the following recording of a part of a reference color chart as the input of the filter:
In Manual mode, against a reference L* of 50, a* of 30, and b* of 80, the following output will be generated by the filter:
In By Group mode the reference L*a*b* values are taken from the average values for each group that the user has assigned pixels to during training; in that case the output will have as many channels as the model has groups. Each channel will be the ΔE value of the input against the reference L*a*b* for each group, calculated according to the CIE 2000 standard.
If one defines two groups by selecting the center of the green color field (second row, second column), and the center of the magenta color field (third row, second column), and then applies the filter in By Group mode, the following output will be generated by the filter for the first channel:
And the second channel of the filter would look like this:
