J. Ruiz-Shulcloper and W.G. Kropatsch (Eds.): CIARP 2008, LNCS 5197, pp. 54–61, 2008. © Springer-Verlag Berlin Heidelberg 2008 Vector Median M-Type L Filter to Process Multichannel Images Antonio Toledo-Lopez, Francisco J. Gallegos-Funes, and Volodymyr Ponomaryov National Polytechnic Institute of Mexico Mechanical and Electrical Engineering Higher School UPALM Zacatenco, Av. IPN s/n, Edificio Z, Acceso 3, 3er. piso; Col. Lindavista, 07738, Mexico D.F., Mexico Phone/Fax: +52-55-57296000x54622 fgallegosf@ipn.mx Abstract. The Vector Median M-type L (VMML) -filter to remove impulsive noise from color images and video color sequences is presented. This filter util- izes multichannel image processing by using the vector approach and the Me- dian M-Type L (MML) algorithm. Simulation results indicate that the proposed filter consistently outperforms other color image filters by balancing the trade- off between noise suppression, detail preservation, and color retention. Keywords: Median M-Type L algorithm, Multichannel image processing, Im- pulsive noise suppression. 1 Introduction Many useful techniques of multichannel signal processing based on vector processing have been investigated due to the inherent correlation that exists between the image channels compared to traditional component-wise approaches [1,2]. Many applica- tions of this technique are color image processing, remote sensing, robot vision, biomedical image processing, and high-definition television (HDTV) [1]. Different filtering techniques have been proposed for color imaging. Particularly, nonlinear filters applied to color images have been designed to preserve edges and details, and remove impulsive noise [1-3]. In this paper, we introduce the Vector Median M-Type L (VMML) -filter. This filter utilizes multichannel image processing by using the vector approach [2,4], and the Median M-Type L (MML) algorithm [5,6]. The proposed filter uses the combined RM-estimator [7] into the L-filter [8] by following way. The redescending M-estimator with different influence functions is combined with the R- (median) es- timator into the L filtering scheme to obtain sufficient impulsive noise suppression for each channel by using the vector approach. We also introduce the use of an impulsive noise detector [9] to improve the properties of noise suppression and detail preserva- tion in the proposed filtering scheme. Simulation results have demonstrated that the proposed VMML filter consistently outperforms other color image filters by balancing the tradeoff between noise sup- pression, detail preservation, and color retention.