Channel (digital image)

About: Channel (digital image) is a research topic. Over the lifetime, 7211 publications have been published within this topic receiving 69974 citations.

Locally Adaptive Color Correction for Underwater Image Dehazing and Matching

Abstract: Underwater images are known to be strongly deteriorated by a combination of wavelength-dependent light attenuation and scattering. This results in complex color casts that depend both on the scene depth map and on the light spectrum. Color transfer, which is a technique of choice to counterbalance color casts, assumes stationary casts, defined by global parameters, and is therefore not directly applicable to the locally variable color casts encountered in underwater scenarios. To fill this gap, this paper introduces an original fusion-based strategy to exploit color transfer while tuning the color correction locally, as a function of the light attenuation level estimated from the red channel. The Dark Channel Prior (DCP) is then used to restore the color compensated image, by inverting the simplified Koschmieder light transmission model, as for outdoor dehazing. Our technique enhances image contrast in a quite effective manner and also supports accurate transmission map estimation. Our extensive experiments also show that our color correction strongly improves the effectiveness of local keypoints matching.

A New Color Management System Based on Human Perception and its Application to Recording and Reproduction of Art Paintings.

Abstract: A new color management system has been developed for high definition color recording and reproduction of art paintings. This system is consisted of high accurate multiband camera, personal computer and projected type display. The multi-band camera is composed by five band filters and single chip CCD camera with 2048x2048 pixels. The reflectance spectra of each pixel of the object were estimated by using five band images within less than the average color difference ∆E*ab = 1.16. The spectral transmittance of five filters was determined by simulated annealing method and principal component analysis of spectral reflectance of paintings. Images of art paintings were reproduced onto the projection type monitor under the consideration of color appearance. In this paper, we describe methods to estimate of reflectance spectra of paintings from five band images, optimization of spectral transmittance of filters and color reproduction of paintings based on the color appearance models. Introduction In recent years, high accuracy digital color imaging system is required in artworks and medical imagings by the advent of information superhighway. In artworks, conventional photographic system has been used for image acquisition and recording. HDTV(High Definition Television) are also used for displaying the paintings, arts and crafts in several 16 Japanese museums. Photographic system, hybrid imaging system used film and scanner, and HDTV system only record the R,G,B three channel images, and they cannot record the reflection spectra of the objects. Reflection spectra is one of the most important information of the objects, and it is not dependent on the spectral radiant distribution of the taking light source. On the other hand, color reproduction of those imaging systems is based on the colorimetric color reproduction as to have same chromaticities between object and image. However, it should be considered the color reproduction based on the human perception such as color adaptation under the viewing condition in an art gallery or museum. We have developed the high accurate imaging systems which is consisted of image acquisition system used multiband CCD camera, color management system based on color adaptation model and estimation of reflection spectra of the objects, and display systems as shown in Figure 1. In the following sections, detail of the developed imaging systems is described. Multiband camera and the Estimation of Reflection Spectra In image acquisition, we used two high quality digital cameras; Fotex F-10 (2048x2048 pixels, 12 bits/pixel ) and Kodak DCS420m (1536x1024 pixels 12bits A/D, 8 bits output). Multiband images were captured by digital camera incorporating a rotating wheel comprising five color filters in front of camera lens. Gray scales with 16 steps and crop marks were recorded with object in each channel, and each channel image data was merged into single file.

Registration and Enhancement of Double-Sided Degraded Manuscripts Acquired in Multispectral Modality

Abstract: We propose a system to process multispectral scans of double-sided documents. It can co-register any number of recto and verso channel maps, and reduce the bleed-through/show-through distortions by exploiting blind source separation. From RGB scans, it is also able to recover the original colors, thus improving the readability of a document while maintaining its original appearance. The recto and verso patterns obtained can then be further analyzed. Many approaches to this problem are based on single-channel or multichannel recto-verso scans. In any case, getting rid of the unwanted interferences is a challenging problem. All the methods relying on pixel intensities, such as the one presented here, need a very accurate co-registration, and this is difficult for recto-verso pairs since the relevant information is often very sparse.

Fast haze removal for a single remote sensing image using dark channel prior

Abstract: Remote sensing images are widely used in various fields. However, they always suffer from the bad weather conditions which also affect their sufficient usage. In order to solve this problem, we propose a simple but effective method to remove haze from a single remote sensing image. Our work is based on the dark channel prior and a common haze imaging model. To eliminate artifacts, we use a low-pass Gaussian filter to refine the coarse estimated atmospheric veil. The experimental results show that our approach achieves good results with very little processing time.

Projection display and method for displaying a total image for projection freeform surfaces or tilted projection surfaces

Abstract: A projection display comprising an imaging unit is described, said imaging unit being designed to generate individual images in a distribution, such as e.g. a two-dimensional distribution, of partial regions of an imaging plane of the imaging unit, and a multi-channel optical unit, which is configured to image per channel in each case an assigned individual image or an assigned partial region of the imaging unit, to be precise such that the imaging of the individual images in a projection surface is at least partly superimposed to form a total image, wherein the projection surface is a non-planar freeform surface, such as e.g. a curved surface, and/or is tilted relative to the imaging plane, and the imaging unit is designed in such a way that constellations of points in the partial images which are respectively superimposed by the multi-channel optical unit in a respective common point in the total image differ depending on the distance between the respective common point in the total image and the multi-channel optical unit. Alternatively, imaging unit and multi-channel optical unit are designed in such a way that a manifestation of a contribution of each channel to the total image varies locally across the total image depending on the distance between the respective common point in the total image and the multi-channel optical unit.