Signal Analysis Calculations
Some quantification values are provided for all circles and squares (quantification shapes) that you place on the image. Signal and related values can only be calculated if one of the quantification shapes is assigned as a background.
Area: Number of pixels enclosed by a shape.
Signal: Sum of the individual pixel intensity values (Total) for a shape minus the product of the background value and area.
Signal = Total - (Background x Area)
Pixel Intensity: A value proportional to the amount of light collected from a single pixel. You can adjust the overall brightness of an image, but pixel intensities remains the same.
Total: Sum of the individual pixel intensities enclosed by a shape.
Signal-to-Noise:
* If more than one background shape is assigned, the Background Standard Deviation is calculated by taking the square root of the pooled variance of all the pixel values from the background shapes.
Background
The background value is used to calculate background-subtracted values (like Signal) for other shapes. Signal will be calculated for shapes once a background shape is assigned.
If one background shape is assigned, the background value used for Signal calculation will be the average of all the pixel values from the background shape.
If multiple background shapes are assigned, the weighted average of all the average values from all the background shapes will be calculated and used as the background value in Signal calculations.
| n | = | Number of background shapes assigned |
| wi | = | Weighting factor used for the background shape. Each background shape is weighted according to the Area of pixels within the shape. |
| Xi | = | Average value of pixels within a background shape |