Check if file is R-Set
[tf, supported] = isrset(filename)
[tf, supported] = isrset(filename) sets tf to true if the file filename is a reduced resolution dataset (R-Set) created by rsetwrite and false if it is not. The value of supported is true if the R-Set file is compatible with the R-Set tools (such as imtool) in the version of the Image Processing Toolbox™ you are using. If supported is false, the R-Set file was probably created by a newer version of rsetwrite than the one in the version of the Image Processing Toolbox you are using.