Design method for orientation-selective CNN filters

We present a simple design technique for realizing CNN linear filters with an orientation-selective frequency response. This design method relies on a 1-D prototype linear filter (either FIR or IIR), whose shape is identical with the cross-section of the oriented filter to be designed. Considering an IIR realization (with minimum-size templates) for the oriented cosine function and knowing the prototype template coefficients, the oriented filter templates can be easily determined. Simulation results are finally given, to illustrate a task of detecting straight lines with a given orientation from an image, using the CNN oriented filter.