Earticle

This study proposes a method to improve the saturation of colors during hue-preserving color image enhancement without the gamut problem. First, the color of each pixel in an input image is projected onto one of three bisecting planes or bisectors of an RGB color cube to increase saturation. Then, that projected color is transformed into a target color with a designated luminance and the same hue as the original color. Experimental results show that the proposed method can enhance color images better than can recent hue-preserving color image enhancement methods.

we describes a method for realizing the color conversion from the tristimulus (X, Y, Z) values to the print ink signals (C, M, Y) by using neural networks. The realized nonlinear color conversion system consists of two hidden layers those have seventeen nodes. We determined the C, M, Y values of the input control signals to compensate the printer nonlinearity of real systems. Experimental results showed that the described method is useful and valid to realized the nonlinear color conversion.

The purpose of this study is to analyze the recent color of Mil-yang, and then to suggest the harmony color combination for making city image. For creating the city’s charming image, investigate the characteristics of Mil-yang city. To investigate city’s color, the process of this study is illustrated as follows: 1) It is investigated city’s socio․liberal history. 2) It is collected and classified the natural color constructing city. 3) It is analyzed that city image's characteristics by citizen's awareness survey and regional resources. Mil-yang city has rich natural scenes and cultural․historical resources. City scenery color was planed and characterized using by these natural scenes, resources and city develop plan. The result indicated that there are three sections which showed natural, clear, classic color. As a base color natural tone is planed, clear color is planed as a sub base color, and classic color is planed as an accent color. By usages and zones of building it is located color scheme was harmoniously planed based on natural basic color. With this study, the artificial color scheme based on the natural scenery, regional resources and citizen's awareness can be an important method to reflect the local image of city. This study was done with a goal to increase resident’s satisfaction and improve development of the city by creating a unique city view and by enabling the city’s identity and competitiveness. Color application as a solution to specialize an area and give a identity to it will find more applicable area in the future.

A novel algorithm for enhancing colour images is proposed. Since DWT is used in image compression and image compression reduces storage space, an algorithm is developed to work directly in DWT space. DWT separates image into high and low frequency components. High frequency components define contrast of an image. Enhancement is done in two steps namely local enhancement and global enhancement. Local enhancement is based on contrast measure and improves contrast. Global enhancement is needed for overall image quality improvement. HSV colour space is used of which V components will undergo enhancement, S component will undergo histogram equalization, and H remains the same for preserving the colour.

This paper presents a luminosity conserving and contrast enhancing histogram equalization method for color images. The histogram equalization is one of the ordinary methods employed for enhancing contrast in TV and images for consumer electronics where unwanted subjective deterioration are frequently occur. Although there have been many solutions to overcome the drawback of histogram equalization, however the method is for RGB color space, which is not well suited for different color spaces. To do this, we use fuzzy set to improve histogram equalization. All RGB images are firstly transformed into different color spaces, and particular channels are applied histogram equalization process. From our 20 test LC images show that HSV color space yields the favorable results in MSE by giving the luminosity conserving ability.

Low quality of underwater image due to color spread and absorption deals with the propagation of light wave length. In this paper we propose exponential equation approach to enhance underwater image color and maintaining color constancy. Exponential approach is conducted through two steps: first, determining the relation between the color intensity of an image underwater and the color intensity of an image in a certain depth; second, determining the coefficient of underwater image color absorption by using least square. The result of exponential approach is measured by using Peak Signal to Noise Ratio, yielding an average value of 19.18 and visually the result of the image color approximates its original color. We concluded that exponential approach can determine the color constancy level which in turns can enhance the underwater image just as its original color.

At present, greatest outdoor video-surveillance, optical remote sensing systems and driver-assistance have been designed to work under decent visibility weather conditions. Less visibility often happens weather of hazy or foggy conditions and can strongly influence accuracy or even general functionality of such vision systems. Fog reduces the visibility of a scene and thus the performance of numerous algorithms of computer vision which use feature knowledge. Fog formation is the function of the depth. Estimation of depth knowledge is under constraint problem if single image is presented. Hence, fog removal need assumptions or prior information. In this paper, present a novel algorithm for fog or haze removal purpose with combination of edge enhancement method, color enhancement method, adjustable empirical function and also Wiener filter for efficient outcomes.

8종의 식용 색소분말(1-8)들에 의하여 현출된 5종의 비 다공성 재질(I-V)에 유류된 잠재지문들 에 대한 색 대비효과와 이미지 개선결과들을 정량적으로 검토하였다. 잠재지문들의 현출은 색소와 재 질을 구성하는 성분들 간 상호작용에 의하여 소수성적인 인력보다는 무기이온들 사이의 쿨롱(Coulomb) 인력이 우세하게 영향을 미친것으로 설명되었다. 공통적으로 색 대비효과에 관하여 유도된 모델들(M1- M13)은 주로 명도(BR) 부 대비효과를 나타내었으며 명도가 색상(H)에 비하여 약 10배 이상 큰 영향을 미치었다. 그러나 CA 훈증의 경우는 반대경향이었다. 유리 스라이드(I)에서 현출된 잠재지문들에 대한 색 대비효과를 방사형 차트(radar chart)로 분석한 결과, 현출성이 양호한 활성색소(1, 2 및 9) 분말들은 색상(H)이 보다 작았으며 비활성 색소(4-8)들은 색상이 큰 경향이었다. 이미지 개선비율(%=(B−A)/A*100) 은 재료 상 비닐필름(IV; 44%), 그리고 색소(1-8)에서는 황색 제4호(5; 300%)가 제일 높았다. 유리 스라 이드(I)에서 현출된 잠재지문에 대한 이미지 개선 전(M1) 및 후(M9) 모델들의 명도(BR) 계수값(M1; ρ= −0.268 및 M9; ρ= −0.429)을 비교한 결과로부터 이미지 개선 전보다 후의 경우에 약 63% 증가한 이 미지 개선 비율을 나타내었다.

The results of the color contrast effects and the enhanced images about the latent fingerprints detected on the 5 nonporous materials (I-V) by 8 different edible colorant powders (1-8) were discussed quantitatively. According to the interaction between the components in colorant powders and materials, the Coulomb force between the inorganic ions influenced predominantly to develop the latent fingerprints rather than hydrophobic attraction force. Commonly, the deriver models on the color contrast effect (M1-M13) indicated the negative brightness (BR) mainly and the brightness influenced more than about 10 times comparing with the hue (H) of color. But those CA fuming shows that the results tend to create objections. The analytical results of the latent fingerprints on the slide glass (I) with radar chart showed that the hue of active colorants (1, 2 & 9) for better developmental images were smaller and that of inactive colorants (4-8) were bigger. The ratio of the image enhancement (%=(BA)/ A*100) was the highest on the vinyl film (IV; 44%) and yellow No. 4 tatrazine (5; 300 %) showed the highest value among the colorant powders (1-8). When the brightness (BR) coefficients (M1; ρ= −0.268 & M9; ρ= −0.429) of the two color contrast models, before the image enhancement (M1) and after the image enhancement (M9), of the developed latent fingerprints on the slide glass (I) were compared, the ratio of the enhanced image was increased by about 63%.

Color enhancement basically deals with color manipulation in digital images. Recently, the technique has become widely used as a result of the increasing use of digital cameras. Retinex-based colorenhancement algorithms are a popular technique. In this paper, retinex with bilateral filtering is proposed to improve the quality of poorly illuminated images. Generally, it consists of three main steps: first, a retinex-based algorithm with color restoration; second, transformation mapping using histogram matching; and finally, smoothing the image using a bilateral filter. The experimental results demonstrate that the proposed method can successfully enhance image contrast while avoiding the halo effect and maintaining the color distribution in the image.

This paper proposes an image-dependent color image enhancement method that uses adaptive luminance enhancement and color emphasis. It effectively enhances details of low-light regions while maintaining well-balanced luminance and color information. To compare the structure similarity and naturalness, we used the tone mapped image quality index (TMQI). The proposed method maintained better structure similarity in the enhanced image than did the space-variant luminance map (SVLM) method or the adaptive and integrated neighborhood dependent approach for nonlinear enhancement (AINDANE). The proposed method required the smallest computation time among the three algorithms. The proposed method can be easily implemented using the field-programmable gate array (FPGA), with low hardware resources and with better performance in terms of similarity.

Since the details in quasi-homogeneous region will be destroyed from the conventional global image enhancement method such as histogram equalization. This defect is caused by the saturation of gray level in equalization process. So the local histogram equalization for each quasi-homogeneous region will be used in order to improve the details in the region itself. To obtain the quasi- homogeneous regions, the original image must be segmented. Here we applied the watershed transform to the interesting image. Since the watershed transform is based on mathematical morphology, therefore, the regions touch can be effectively separated. Hence two adjacent regions which have the similar gray pixels will be split off. The process will be independently applied to three different spectral images. Then three different colors are assigned to each processed image in order to produce a color composite image. By the proposed algorithm, the result image shows the better perception on image details. Therefore, the high efficiency of image classification can be obtained by using this color image.

In this paper, a new light-value approaching method to enhance a color image by excluding the effect of incident illumination is proposed. The method uses the fundamental vector transformation in which an estimated color of illumination is rotated to the white color of natural daylight. Then the transformed red, green, and blue values of each pixel are nonlinearly mapped into the 8-bit values to enhance intensity and saturation in the dark portion of the image. The proposed algorithm can produce the enhanced color image fast and efficiently without any space conversion or noticeable distortion.

The skin color of a human being is the important memory color influencing image quality for color display. Therefore, in this paper, the preferred skin color axis is defined on HSV color space by analyzing some previous research, and the preferred skin color reproduction algorithm is performed by rotating the center axis of skin distribution of an input image to the preferred skin color axis.

The wavefront printer records a volume-reflection hologram as a two-dimensional array of elemental holograms from computer-generated holograms (CGHs) displayed on a spatial light modulator (SLM). The wavefront coming from the object is extracted by filtering in the spatial-frequency domain. This paper presents a method to improve color reproduction in a wavefront printer with spatial division of exposures at primary colors, by adaptive partitioning of the SLM in accordance with the color content encoded in the input CGHs, and by the controllable change of exposure times for the recording of primary colors. The method is verified with a color wavefront printer with demagnification of the object beam. The quality of reconstruction achieved by the proposed method proves its efficiency in eliminating the stripe artifacts that are superimposed on reconstructed images in conventional mosaic recording.

Endoscopic examination plays a crucial role in the diagnosis of upper gastrointestinal (UGI) tract diseases. Despite advancements in endoscopic imaging, the detection of subtle early cancers and premalignant lesions using white-light imaging alone remains challenging. This review discusses two novel image-enhanced endoscopy (IEE) techniques-texture and color enhancement imaging (TXI) and red dichromatic imaging (RDI)-and their potential applications in UGI diseases. TXI enhances texture, brightness, and color tone, which improves the visibility of mucosal irregularities and facilitates earlier detection of neoplastic lesions. Studies have suggested that TXI enhances the color differences between lesions and the surrounding mucosa and improves the visibility of the lesion. TXI aids in the diagnosis of various UGI diseases, including early gastric cancer, esophageal cancer, premalignant conditions such as atrophic gastritis and Barrett’s esophagus, and duodenal tumors. RDI utilizes specific wavelengths to enhance the visualization of deep blood vessels or bleeding points, aiding in the rapid and accurate identification of bleeding sources during endoscopic procedures. Although promising, TXI and RDI require further large-scale studies across diverse populations to establish their clinical utility, diagnostic performance, and cost-effectiveness before integration into the guidelines. Standardized training is also required for effective utilization. Overall, these IEE techniques has the potential to improve the diagnosis and management of UGI.

Multi-scaled retinex algorithm is generally used to enhance the local contrast and remove the illuminant component. However, if the chromatic distribution of an original image is not uniform and dominated by a certain chromaticity, the chromaticity of resulting image depends on the dominant chromaticity of the original image, thereby inducing the color distortion. In this paper, a modified multi-scaled retinex method to reduce the influence of the dominant chromaticity in the image is proposed using a average chromaticity of original image and global illuminant chromaticity. In addition, to compensate saturation, the chroma value of the resulting image is enhanced based on that of the original image in the CIELAB space.

Color image is largely corrupted by various ambient illumination. However, human perceives always white color as white under any illumination because of a characteristic of human vision, called color constancy. In the conventional algorithm which applied the constancy effect, after the RGB color space is transformed to the IHS(Intensity, Hue, and Saturation) color space, then the hue is preserved and the intensity or the saturation is properly enhanced. Then the enhanced IHS color is reversely transformed to the RGB color space. In this process, the color distortion is included due to the color gamut error. But in the proposed algorithm, there is not transformation. In that, the RGB color is considered as 3 dimensional color vector and we assume that white color is the natural daylight. As the color vector of the illumination can be calculated as the average vector of R, G, and B image, we can achieve the constancy effect by simply rotating the illumination vector to the white color vector. The simulation results show the efficiency of the vector rotating process for color image enhancement.

영상의 화질을 향상시키기 위하여 콘트라스트(contrast)를 향상시키는 기법이 많이 사용된다. 컬러 영상의 콘트라스트를 향상시키는 경우에 컬러의 saturation이 높은 순수한 색에 대해서는 과도한 콘트라스트 향상으로 인한 색 포화 현상이 발생할 수 있다. 본 논문에서는 HSI 컬러 공간에서 saturation 성분을 이용하여 순수한 색에 대한 과도한 콘트라스트 향상으로 발생할 수 있는 색 포화 현상을 방지할 수 있는 기법과 YCbCr 컬러 공간에서도 동일한 효과를 보이는 컬러 영상 화질 향상 기법을 제안한다. 다양한 영상에 대한 실험 결과 제안하는 기법이 기존의 방법에 비하여 좋은 화질의 영상을 생성하는 것을 보인다.

The contrast of the intensity components of color images usually needs to be improved in order to enhance the visual quality of color images. However, pure color regions can be saturated due to the excessive enhancement of that color. In this paper, a new method for enhancing the visual quality of color images using saturation components in the HSI color space is proposed, and the same enhancement technique in the YCbCr color space is proposed. Computer simulations show that the proposed method provides improved visual quality compared to the conventional methods.

본 논문에서는 라플라시안 피라미드를 이용하여 컬러 영상의 밝기 및 색상을 개선하는 방법을 제안한다. 제안하는 방법은 입력 영상을 라플라시안 피라미드로 구성한 후 저해상도 근사 영상을 이용하여 영상의 전체적인 밝기를 개선하고 대역 통과 영상들을 이용하여 대비를 개선한 후 입력 영상의 밝기 값에 따라 적응적으로 색상을 재현함으로써 최종적으로 컬러 영상의 화질을 개선한다. 실험 결과 제안하는 방법은 영상 조명 특성에 강인한 화질 개선 성능을 보여주었으며 동영상에 적응시에도 자연스러운 화질 개선 결과를 얻을 수 있었고 실시간 처리가 가능한 수행 속도를 보여주었다.

칼라 영상은 단색조의 영상에 비해 인간의 시각을 크게 향상시킨다. 따라서 칼라 영상 처리에 관한 연구는 매우 중요하다. 칼라 영상은 센서 잡음이나 채널 전송 에러에 의해 생기는 잡음에 의해 자주 오염되어진다. 이러한 칼라 잡음을 제거하기 위해 여러 형태의 필터들이 개발되어 왔는데 혼합된 잡음에서 벡터 $\alpha$-trimmed 평균 필터는 우수한 성능을 보였다. 그러나, 벡터 $\alpha$-trimmed 평균 필터는 필터링 과정이 영상의 전 영역에 걸쳐 균일하게 적용되어지기 때문에 윤곽선 이동이 일어나 blurring 현상이 심하게 나타나는 문제점이 있다. 이러한 문제점을 개선하기 위해 본 논문에서는 윤곽선 영역과 smooth 영역을 구분한 뒤 각 영역에 적합한 선택적인 필터링을 하는 조건적인 퍼지 클러스터 필터를 제안하였고 제안된 조건적인 퍼지 클러스터 필터는 기존의 벡터 $\alpha$-trimmed 평균 필터에 비해 혼합된 잡음에서 우수한 성능을 보였다.