The same reference direction in used for all output images, and is equal to the reference direction in the first input image. For each input image, the anti-clockwise angle from this reference direction to the effective analyser position is found. These analysis angles are then sorted into bins of size given by parameter BIN. The first bin extends from the analysis angle given by parameter ORIGIN (typically zero) to the value (ORIGINBIN). The second bin extends from (ORIGINBIN) to (ORIGIN2BIN), etc. If parameter TWOPI is FALSE, the number of bins used is chosen so that they cover a range of ORIGIN to (180ORIGIN) degrees, and input images with analysis angles outside this range are mapped into the range by subtracting (or adding) a multiple of 180 degrees. If parameter TWOPI is TRUE, the number of bins used is chosen so that they cover a range of ORIGIN to (360ORIGIN) degrees, and input images with analysis angles outside this range are mapped into the range by subtracting (or adding) a multiple of 360 degrees.
An output image is produced for each bin containing more than the minimum required number of images specified by parameter MININ. The output DATA value at each pixel is the mean of the corresponding pixels in the input images which fall within the range of analysis angles covered by the output image. A VARIANCE component is added to the output image in which each pixel contains the standard error of the corresponding input pixels. If there are less than 2 good input pixel values, then the VARIANCE value is set bad.
Each output image contains a POLPACK extension in which the ANLANG value (which specifies the analysis angle) is set to the mean of the analysis angles for the corresponding input images. This mean value refers to the output reference direction which is inherited from the first input NDF.
". These images must be aligned pixel-for-pixel.
"are binned into a set of intensity images each covering a range of 10 degrees of analysis angle. These output images are called
Any transmission (T) or efficiency (EPS) values in the POLPACK extensions of the input images are ignored. The output images will not contain any T or EPS values and so default values of 1.0 will be used for both when POLCAL is run.
Any FILTER or IMGID values in the POLPACK extensions of the input images are ignored. The output images will not contain any FILTER or IMGID values.
Any VARIANCE components in the input images are ignored.