• Journal of the Korea Convergence Society
• /
• v.7 no.6
• /
• pp.1-6
• /
• 2016

In this paper, we propose an image enhancement method for vehicle recorder by dividing the images into sub-images and finding local histograms of the sub-images. The proposed method includes the following steps. Firstly, the input image is divided into ($N{\times}M$) pieces. And the sub-images are used to make groups using the adjacent piece-images (eg. piece-imagei,j, piece-imagei,j+1, piece-imagei+1,j and piece-imagei+1,j+1). Secondly, the contrast enhancement processes are executed using the local histogram of the sub-images. Finally, overall image is reconstructed by using a transfer function that reflects the characteristics of the sub-image. The proposed method might achieve more enhanced images for vehicle recorder by suppressing excessive image contrast.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.239-242
• /
• 2004

This paper presents a novel contrast enhance algorithm for images displayed with bright environment light. This algorithm is designed to preserve local contrast based on the luminance ratio of the pixel to its local surround in attention. This algorithm improves image quality of projectors in a bright room.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.62 no.2
• /
• pp.90-94
• /
• 2013

In this paper, we propose a new algorithm to improve the contrast ratio, to preserve information of bright regions and to maintain the color of backlight image that appears with a great relative contrast. Backlight images of the natural environment have characteristics for difference of local brightness; the overall image contrast improvement is not easy. To improve the contrast of the backlight images, MSR (Multi-Scale Retinex) algorithm using the existing multi-scale Gaussian filter is applied. However, existing multi-scale Gaussian filter involves color distortion and information loss of bright regions due to excessive contrast enhancement and noise because of the brightness improvement of dark regions. Moreover, it also increases computational complexity due to the use of multi-scale Gaussian filter. In order to solve these problems, a linear MSR is performed that reduces the amount of computation from the HSV color space preventing the color distortion and information loss due to excessive contrast enhancement. It can also remove the noise of the dark regions which is occurred due to the improved contrast through edge preserving filter. Through experimental evaluation of the average color difference comparison of CIELAB color space and the visual assessment, we have confirmed excellent performance of the proposed algorithm compared to conventional MSR algorithm.

• Current Optics and Photonics
• /
• v.6 no.3
• /
• pp.304-312
• /
• 2022

Digital images of cultural relics captured using line scan cameras present limitations due to uneven intensity and low contrast. To address this issue, this report proposes a colour linear array image enhancement method that can maintain a constant colour. First, the colour linear array image is converted from the red-green-blue (RGB) colour space into the hue-saturation-intensity colour space, and the three components of hue, saturation, and intensity are separated. Subsequently, the hue and saturation components are held constant while the intensity component is processed using the established intensity compensation model to eliminate the uneven intensity of the image. On this basis, the contrast of the intensity component is enhanced using an improved local contrast enhancement method. Finally, the processed image is converted into the RGB colour space. The experimental results indicate that the proposed method can significantly improve the visual effect of colour linear array images. Moreover, the objective quality evaluation parameters are improved compared to those determined using existing methods.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2017.11a
• /
• pp.101-103
• /
• 2017

본 논문은 human visual system(HVS)에 따른 주파수 민감도와 공간에서 다양한 특성들을 구현하기 위한 신호처리 방법을 개발하였다. 인간의 눈은 주파수 성분에 따라 민감도가 다르며 초점에서 멀수록 인지 가능한 해상도가 떨어진다. 주파수 민감도를 구현하기 위해서 본 논문은 영상 신호의 에너지 스펙트럼 모양이 contrast sensitivity function(CSF)의 모양이 되도록 하여 영상 신호의 에너지를 증가시켰으며 신호 방향에 적응적인 multiband energy scaling 방법을 개발하였다. 기존의 시스템에서 능률만을 향상시키는 기존의 분석 모델과 비교하면 개발한 방법은 HVS에 좀 더 적절하고 선호되게 영상 신호를 처리할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.44 no.2 s.314
• /
• pp.37-45
• /
• 2007

We propose an adaptive image enhancement method for epigraphic images, which is based on local statistics. Local statistics of the image are utilized for adaptive realization of the enhancement, that controls the contribution of the smoothing or sharpening paths. Image contrast enhancement occurs in details and noises are suppressed in smooth areas. For modeling the epigraphic image, pre~process is achieved by HSDI(Hanzi squeezed digital image). We have calculated the local statistics from this HSDI model. Application of this approach to HSDI has shown that processing not only smooths the background areas but also improves the subtle variations of edges, so that the word regions can be enhanced. Experimental results show that the proposed algorithm has better performance than the conventional image enhancement ones.

• Proceedings of the KIPE Conference
• /
• 2002.11a
• /
• pp.186-189
• /
• 2002

Real-time thermal image is obtained by thermal imaging systems measuring radiant emittence according to law of Plank's blackbody radiation. The histogram of thermal image is not uniform. The signal bands of background and target are separated and grouped in narrow bands. In such a system, contrast enhancement indispensible to distinguish target from background. In this study, plateau histogram equalization using local histogram is proposed for contrast enhancement.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.12
• /
• pp.58-66
• /
• 1999

In this paper, an advanced histogram equalization algorithm for contrast enhancement is presented. Histogram equalization is the most popular algorithm. Global histogram equalization is simple and fast, but its contrast enhancement power is relatively low. Local histogram equalization, on the other hand, can enhance overall contrast more effectively, but the complexity of computation required is very high. In this paper, a low pass filter type mask is used to get a sub-block histogram equalization function to more simply produce the high contrast. The low pass filter type mask is realized by partially overlapped sub-block histogram equalization (POSHE). With the proposed method. the computation overhead is reduced by a factor of about one hundred compared to that of local histogram equalization while still achieving high contrast.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.12
• /
• pp.51-57
• /
• 1999

In this paper, an adaptive thresholding of the nonuniformly contrasted images is proposed through using the contrast pre-enhancement of the local regions and the bilinear interpolation between the local threshold values. The nonuniformly contrasted image is decomposed into 9${\times}$9 sized local regions, and the contrast is enhanced by intensifying the gray level difference of each low contrasted or blurred region. Optimal threshold values are obtained by iterative method from the gray level distribution of each contrast-enhanced local region. Discontinuities are reduced at the region of interest or at the characters by using bilinear interpolation between the neighboring threshold surfaces. Character recognition experiments are conducted using backpropagation neural network on the characters extracted from the nonuniformly contrasted document, PCB, and wafer images binarized through using the proposed thresholding and the conventional thresholding methods, and the results prove the relative effectiveness of the proposed scheme.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.971-972
• /
• 2006

We have demonstrated Carbon Nanotube Back Light Unit (CNT-BLU) which has a triode structure. Local dimming scheme was introduced to the BLU driving system. With this driving method, contrast ratio enhanced 20 times higher than that of conventional Cold Cathode Fluorescent Lamp (CCFL) BLU.