Abstract This article proposes a confusion-line separation algorithm in a CIELAB color space using color segmentation for protanopia and deuteranopia. Images are segmented into regions by grouping adjacent pixels with similar color information using the hue components of the images. To this end, the region-growing method and the seed points used in this method are the pixels that correspond to peak points in hue histograms. In order to establish a color vision deficiency (CVD) confusion-line map, the authors establish 512 virtual boxes in an RGB 3-D space so that boxes existing on the same confusion line can be easily identified. The authors then check whether segmented regions exist on the same confusion line and perform a color adjustment in a CIELAB color space so that all adjacent regions exist on different confusion lines in order to provide the best color-identification effect for those with CVDs.

Abstract The conventional methods for color image quantization are aimed at obtaining the resulting image with a minimum mean squared error (MSE). Yet human perceptual satisfaction is not always related to the MSE. This article presents a color quantization method that uses a lightness enhancement factor for better representation of the gradation and a perceptual threshold for preservation of perceptually sensitive colors in the CIELUV color space. The experimental results show that the proposed method provides better visual quality when representing the gradation and better preserves the perceptually sensitive colors compared to the conventional methods even if the MSE of the proposed method is slightly higher than those of the conventional methods.

Abstract Image segmentation is typically used to detect object contours in an image. In this article, a threshold-gradient based image segmentation method (TGISM) is proposed to extract objects from an image, based on the techniques of object contour gradient, gradient vector flow, and thresholding. In this article, a thresholding method minimizing within-class variance is also presented. The experimental results validate that the TGISM can give better segmentation results than the results obtained by the existing set of methods reported in the literature. In this article, a genetic algorithm based on accumulated historical data is proposed for determining the appropriate values of the parameters used in the TGISM.

Abstract This article describes automatic road boundary extraction from a high resolution true orthoimage using the Ribbon Snakes algorithm. We assume the existence of prior information for the rough range of road widths in the scenes and road centerline data. Previous works on road boundary extraction have been focused on rural areas, using the same approach. Applying the Ribbon Snakes algorithm to an urban area, we encounter multiple-local-minima problem due to cars and lane markings. We overcome this problem by repeating the optimization of the Ribbon Snakes model at different widths. With the existing road centerlines, fixed width Ribbon Snakes (FXWRS) is applied and its total energy after optimization is stored. After changing the road width, FXWRS is reapplied and the total energy is again stored. By comparing the total energies for each of the road widths, we determine the optimum width that produces the least total energy. Applying FXWRS with the optimum width and road centerline, refined road boundaries are obtained. We show the feasibility of this approach by comparing results with ground truth.

Abstract Marbling is a recurrent print defect that can be observed on polyvinyl(chloride) (PVC) film prints. It can be defined as undesired irregularity in print, which gives a texture to a solid area. Unlike mottling, marbling is a high frequency and quite regular defect, which can have many causes, whose identification and removal rely on accurate and reliable quantification of marbling on printed PVC substrates. Moreover, the evaluation of this defect must agree with human perception. The aim of this article is to evaluate the use of methods presented in the literature for mottle characterization on printed paper in order to quantify marbling on printed PVC film. Two methods, ISO standard and frequency analysis (based on Fourier transform), were used in this study to characterize a set of PVC printed substrates with increasing marbling. The resulting marbling indices were compared to visual print marbling assessment. The results demonstrated that methods applied to quantify mottle on paper can be transposed to evaluate marbling on printed PVC films.

Abstract In 2000, the author and his team reported the effect of the energy from the heat and nip pressure supplied to the toner. They found that, in typical roll fusers, the fuse grade changes very little when the width of the nip is enlarged by reducing the hardness of the pressure roll’s elastic layer without increasing the pressing load. This observation yielded a fuse grade contour in coordinates of heat supply and pressure from which the author could derive design concepts and procedures for basic specifications of roll fusers. This prior study, however, had some outstanding issues: especially in regard to fusing phenomena, the supplied heat is assumed to be equal to the thermal energy used for fusing. However, the absorbed or latent heat should be examined, and rheology should be taken into consideration when this heat is to be compared with the work due to the nip pressure. This article reviews and reconsiders the situation presented in the prior study. It provides a solution describing the roles and effects of thermal energy and work due to nip pressure during toner fusing.