Affiliations: [a] Escola Politécnica – Universidade de São Paulo, Av. Prof. Luciano Gualberto, São Paulo, SP, Brazil | [b] Diretoria dos Cursos de Informática – Universidade Nove de Julho, São Paulo, SP, Brazil
Correspondence:
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Corresponding author: Dr. Hae Yong Kim, Associate Professor, Universidade de São Paulo, Av. Prof. Luciano Gualberto, tr. 3, 138, ZIP 05508-010, São Paulo, SP, Brazil. Tel.: +55 11 3091 5605; E-mail: [email protected].
Abstract: Template matching is a technique widely used for finding patterns in digital images. A good template matching should be able to detect template instances that have undergone geometric transformations. In this paper, we proposed a grayscale template matching algorithm named Ciratefi, invariant to rotation, scale, translation, brightness and contrast and its extension to color images. We introduce CSSIM (color structural similarity) for comparing the similarity of two color image patches and use it in our algorithm. We also describe a scheme to determine automatically the appropriate parameters of our algorithm and use pyramidal structure to improve the scale invariance. We conducted several experiments to compare grayscale and color Ciratefis with SIFT, C-color-SIFT and EasyMatch algorithms in many different situations. The results attest that grayscale and color Ciratefis are more accurate than the compared algorithms and that color-Ciratefi outperforms grayscale Ciratefi most of the time. However, Ciratefi is slower than the other algorithms.
Keywords: Template matching, RST-invariance, color invariance
