Yule-Nielsen Correction Factor - "N" Factor
For plate measurement, the geometrical dot size is what is important. Therefore, the light trap effect, or optical gain, must be factored out by using the Yule-Nielsen formula for the calculation of the dot area.You can switch off the Yule-Nielsen-correction by setting the Y-N-coefficient to 1.0. In this case you are actually using the Murray-Davies formula.
You may also wish to consider using a video based plate reading device, such as the PlateScope.
