Averaging (Box) filter

Applying an averaging filter (also known as mean or box filter) results in an image in which the value of each pixel is equal to the average intensity of pixels from the input image in a given neighborhood. Filtering can be defined as a convolution of the image with a kernel given by an l\times l matrix containing equal entries that sum to one, thus

K_{\mathrm{AV}}=\frac{1}{l^{2}}\left[\begin{array}[]{ccc}1&\cdots&1\\ \vdots&\ddots&\vdots\\ 1&\cdots&1\end{array}\right]\,.

Kernel K_{\mathrm{AV}} is separable and the vector \boldsymbol{k} (see convolution with separable kernels) can be composed from values k_{i}=1/l, where i=1,\ldots,l. The kernel size l is a user-specified parameter.

Threshold for approximate localization of molecules

The threshold value can be specified by users as an expression combining mathematical functions and operators with variables based on the current raw or filtered image. Variables provided by this filter are:

Box.I current raw input image
Box.F corresponding filtered image