LN: Natural Logarithm of an Image

 
Form : LN source [INV]
LN replaces the pixel values in the image 'source' by their base-e logarithm values. Any pixels whose original values were less than or equal to 0 are replaced by -30 in the resulting image. If the INV keyword is specified, the inverse log is taken

Example:

LN 3
take the natural log of each pixel in buffer 3.