Abstract: A sample mask is used to control which samples are used in a filtering operation such as bilinear filtering. A conventional filtering operation reads a set of samples based on a single coordinate and combines the samples to produce a filtered sample value. Such filtering operations are performed conventionally using fixed function units designed specifically to perform such filtering operations. However, for some applications, excluding one or more of the samples in producing a filtered sample value is desirable. In other applications, combining the samples using different weighting factors is also desirable. Techniques are disclosed herein for extending the capabilities of existing filtering units, for example, to exclude one or more samples in the filtering operation and for specifying different weighting rules for combining the samples.