Color quantization is to design a color palette having almost no noticeably perceived difference between original and quantized images. In this paper, to design such a palette, the color quantization algorithm is considered in two parts: the selection of a proper distortion measure and the design of an optimal palette. The proper selection of distortion measure in the quantization is important ...

The increasing availability of high performance, low priced, portable digital imaging devices has created a tremendous opportunity in document image acquisition by supplementing traditional scanning using flatbed scanners and mounted cameras. However, the portability of the camera presents new challenges in document image analysis and recognition in general and handwriting recognition in partic...

A new method for data hiding in grayscale images based on a human vision model with distortion-minimizing capabilities is proposed for covert communication. Each of the eight bit planes of an input grayscale image is viewed as a binary image, into which message data are embedded horizontally. To minimize the image distortion, two optimization techniques, namely, block pattern coding and dynamic...

Image rectification is the process of applying a pair of 2 dimensional projective transforms, or homographies, to a pair of images whose epipolar geometry is known so that epipolar lines in the original images map to horizontally aligned lines in the transformed images. We propose a novel technique for image rectification based on geometrically well defined criteria such that image distortion d...

After an image is printed-and-scanned, it is usually filtered, rotated, scaled, cropped, contrast-andluminance adjusted, as well as distorted by noises. This paper presents models for the print-and-scan process, considering both pixel value distortion and geometric distortion. We show properties of the discretized, rescanned image in both the spatial and frequency domains, then further analyze ...

In this paper, we propose a method of compressing surveillance video that, given a foreground segmentation, encodes the regions of interest using a block-based approach that reduces the distortion due to segmentation errors. Compression of each region of interest, as well as the background image, is achieved using JPEG 2000. With an estimate of the background image being updated periodically, e...

In recent years attention has been turned to the use of neural network-derived algorithms to restore images using a model-based approach. Considering an M by M input image, in most cases the image degradation model is a spatially and temporally invariant linear distortion described by the equation (Pratt [1]) (Andrews and Hunt [2]): Where f and g are the M2 by 1 lexicographically organized orig...

This paper presents a model for correcting the effects of barrel and pincushion lens distortion that preserves the scale of the captured image. This is significant as the model is able to correct for a practical range of the aforementioned types of lens distortion while maintaining the scale helps minimize the loss of the corrected image’s resolution. The functional inverse of the model is deri...

Table 1. A comparison of valid tensors in the DTIs based on DWIs of different strategies of distortion correction. Our method provided the best result, while some other method may increase the number of ill-conditioned tensors (nonpositive definite). (a) (b) (c) (d) Figure 1. A comparison of distortion correction using different approaches. First Row: The simulated dataset; Second Row: The real...

This paper introduces the algorithm on SAR image orthorectification based on polynomial rectification and height displacement correction, and experiments according to the algorithm on ERS-2, RADARSAT, and airborne SAR image in mountain area. Many factors result in SAR image distortion, and most of them can be corrected by polynomial rectification. But the distortion of SAR image brought by elev...