# HistContrast

Computes image contrast by finding the optimum binary threshold, and then taking the difference of the mean greyscale above the threshold and the mean greyscale below the threshold. The contrast value is always returned as a number from 0 to 255.

## HistContrast Inputs

Parameter | Description
Structure | This argument must reference a spreadsheet cell containing a Histogram or ColorHist data structure.
FirstBin | Specifies the first "bin" (0 to 255; default = 0) used to define the Histogram.
LastBin | Specifies the last "bin" (0 to 255; default = 255) used to define the Histogram.

## HistContrast Outputs

Returns | A value representing the image contrast, or #ERR if any of the input parameters are invalid.