For example, if the Raster has integer values ranging from -1 to 3 and the value that I am only interested in is 3, I then want to assign values -1 to 2 to 0 and then have the 3 value set to the value of 1. (Similar idea to IDRISI Raster REASSIGN tool.)
I am ultimately trying to find the frequency of a certain cell value in a time series of Rasters of the same extent. To find the frequency of 'cloud' pixels in a certain area over the course of 15 years.
For example, using Raster Calculator to add up the above output Rasters into a single Raster to find the frequency of that cell value since it would have a value of 1 in each Raster.
Additionally, if there is some kind of tool in QGIS that would do a time series frequency comparison on a per pixel basis like the above described that would be good, but so far I have not found such a tool in QGIS.