findScalingFactor: Find scaling factor from object of known length
In RFishBC: Back-Calculation of Fish Length

findScalingFactor

R Documentation

Find scaling factor from object of known length

Description

This computes a scaling factor (i.e., a multiplier that is used to convert image lengths to actual lengths) from user selected endpoints of an object of known length on the image given in img and the actual known length given in knownLength. See Details.

Usage

findScalingFactor(
  img,
  knownLength,
  windowSize,
  deviceType,
  closeWindow,
  col.scaleBar,
  lwd.scaleBar,
  pch.sel,
  col.sel,
  cex.sel,
  pch.del,
  col.del
)

Arguments

`img`	A string that indicates the image (must be PNG, JPG, BMP, or TIFF) to be loaded and plotted. By default the user will be provided a dialog box from which to choose the file. Alternatively the user can supply the name of the file (will look for this file in the current working directory).
`knownLength`	See details in `RFBCoptions`.
`windowSize`	See details in `RFBCoptions`.
`deviceType`	See details in `RFBCoptions`.
`closeWindow`	See details in `RFBCoptions`.
`col.scaleBar`	See details in `RFBCoptions`.
`lwd.scaleBar`	See details in `RFBCoptions`.
`pch.sel`	See details in `RFBCoptions`.
`col.sel`	See details in `RFBCoptions`.
`cex.sel`	See details in `RFBCoptions`.
`pch.del`	See details in `RFBCoptions`.
`col.del`	See details in `RFBCoptions`.

Details

To apply the scaling factor determined with this function to images opened in digitizeRadii is is important that the images were created with the EXACT same magnification, are saved with the EXACT same dimensions (and aspect ratio), and the EXACT same value for windowSize= is used.