# HistMean

Computes the greyscale mean, by summing the greyscale values for all pixels in the specified range, and then dividing by the count of pixels in the same range.

## HistMean 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.

## HistMean Outputs

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