Image Quality Assessment Using Spatial Frequency Component

Image quality assessment (IQA) is a crucial technique in perceptual image/video coding, because it is not only a ruler for performance evaluation of coding algorithms but also a metric for ratio-distortion optimization in coding. In this paper, inspired by the fact that distortions of both global and local information influence the perceptual image quality, we propose a novel IQA method that inspects these information in the spatial frequency components of the image. The distortion of the global information mostly existing in low spatial frequency is measured by a rectified mean absolute difference metric, and the distortion of the local information mostly existing in high spatial frequency is measured by SSIM. These two measurements are combined using a newly proposed abruptness weighting that describes the uniformity of the residual image. Experimental results on LIVE database show that the proposed metric outperforms the SSIM and achieves performance competitive with the state-of-the-art metrics. ? 2009 Springer-Verlag Berlin Heidelberg.EI

No-reference blur assessment of dermatological images acquired via mobile devices

One of the most important challenges of dealing with digital images acquired under uncontrolled conditions is the capability to assess if the image has enough quality to be further analyzed. In this scenario, blur can be considered as one of the most common causes for quality degradation in digital pictures, particularly in images acquired using mobile devices. In this study, we collected a set of 78 features related with blur detection and further analyzed its individual discriminatory ability for two dermatologic image datasets. For the dataset of dermoscopic images with artificially induced blur, high separation levels were obtained for the features calculated using DCT/DFT and Lapacian groups, while for the dataset of mobile acquired images, the best results were obtained for features that used Laplacian and Gradient groups

FPGA Based Implementation of an Invisible-Robust Image Watermarking Encoder

Both encryption and digital watermarking techniques need to be incorporated in a digital rights management framework to address different aspects of content management. While encryption transforms original multimedia object into another form, digital watermarking leaves the original object intact and recognizable. The objective is to develop low power, real time, reliable and secure watermarking systems, which can be achieved through hardware implementations