Method and apparatus for integrating multiple 1-D filters into a digital image stream interface

The invention relates to hardware implementations of one-dimensional filters applied to digital images such as are supplied from digital cameras, especially applying multiple such filters including recursive filters to a stream of digital images. More specifically, the resulting filtered digital image may then be processed in software on a general-purpose computer to complete a two-dimensional digital image filter. In a method of integrating one or more l-dimensional filters into a digital image stream interface a single digital video input is processed by multiple 1-dimensional digital image filters, especially recursive filters, and combined into a single digital image stream which can be transmitted via a high-speed interface to a host computer's memory such that each 1-dimensional filter output can be automatically extracted and placed into its own separate memory buffer for subsequent processing by a secondary image processing device. This additional processing can include the second pass of a two-pass separable filter implemented in software on a general-purpose CPU, and in particular can result in the generation of an image pyramid. This combined hardware and software approach can produce low-cost 2-D digital image filter implementations small enough to be added to existing standard ASIC's while still retaining high performance.