Optimal cubic filter for image scaling

摘要

In the paper a theoretical analysis of optimal cubic filter for image scaling is investigated. Starting from the analysis of the cubic filter in the frequency domain, and then by minimizing the magnitude of the frequency response, |H(ω)|, over the interval 0.5 ≤ω≤the coefficients for the cubic filter can be obtained in terms of aliasing suppression and clear text display. By incorporating the previous result obtained by Keys with the new result obtained here, the optimal coefficients for the cubic filter can be obtained. Since the optimal cubic filter is obtained by suppressing the frequency response beyond the Nyquist frequency, it can be expected that the aliasing can be suppressed by using the proposed optimal cubic filter. The proposed optimal filter has performed a text enlargement example, and simulation results justify our theoretical analysis. It shows that the proposed method has very good performance in image scaling, especially in performing text enhancement.