This plug-in filter uses convolution with a Gaussian function for smoothing.
It uses the same algorithm as the ImageJ built-in Process>Filters>Gaussian Blur
filter, but has higher accuracy, especially for float (32-bit) images
(leading to longer calculation times, however).
Sigma (Radius) means the radius of decay to exp(-0.5) ~ 61%, i.e. the standard
deviation sigma of the Gaussian.
Scaled Units means that the value of sigma is not in pixels but rather in units
defined by the x&y image scale (for images with spatial calibration)
Like all convolution operations in ImageJ, this filter assumes that
out-of-image pixels have a value equal to the nearest edge pixel.
This gives higher weight to edge pixels than pixels inside the image,
and higher weight to corner pixels than non-corner pixels at the edge.
Thus, when smoothing with very high blur radius, the output will be
dominated by the edge pixels and especially the corner pixels. In the
extreme case of a very high a blur radius, e.g. 1e20, the image will
be replaced by the average of the four corner pixels.
For increased speed, except for small blur radii, the lines (rows or
columns of the image) are downscaled before convolution and upscaled
to their original length thereafter.
Author: Werner Bailer (firstname.lastname@example.org) Date: 2001/10/29 Source: DCT_.java Installation: Download DCT_.class and DCT.class to the plugins folder and restart ImageJ. Description: Calculates forward and inverse
Authors: Olivier Marchal (marchal_olivier at hotmail.fr) and Jerome Mutterer (jerome.mutterer at ibmp-ulp.u-strasbg.fr) History: 2005/02/14: First version 2009/10/13: Emil Martinec fixed a bug in convolution between
Author: Wayne Rasband (email@example.com) Date: 2000/05/31 Requirements: ImageJ 1.17j or later Limitations: Limited to square kernels and real images Source: Real_Convolver.java Installation: Download Real_Convolver.class to