To improve the visualization of an image, the image enhancement techniques enhance the assured features of an image. In this work, the algorithm will enhance medical as well as normal or natural images which are captured in low light and day light conditions. An enhanced adaptive histogram equalization based local contrast preserving technique is developed with the help of image processing methods such as changing colour spaces, inverting images, dehazing, increasing saturation etc. The algorithm proposed here is intended to maintain the local image details while attaining the contrast enhancement. To express the performance of this algorithm, the image quality metrics calculated are peak signal to noise ratio and normalized absolute error. This metric parameters show that this model has better performance when compared to other existing methods.

https://iopscience.iop.org/article/10.1088/1757-899X/1022/1/012119/pdf

An Enhanced Adaptive Histogram Equalization Based Local Contrast Preserving Technique for HDR Images

This paper presents a high dynamic range (HDR) image zero watermarking method based on dual tree complex wavelet transform (DT-CWT) and quaternion. In order to be against tone mapping (TM), DT-CWT is used to transform the three RGB color channels of the HDR image for obtaining the low-pass sub-bands, respectively, since DT-CWT can extract the contour of the HDR image and the contour change of the HDR image is small after TM. The HDR image provides a wide dynamic range, and thus, three-color channel correlations are higher than inner-relationships and the quaternion is used to consider three color channels as a whole to be transformed. Quaternion fast Fourier transform (QFFT) and quaternion singular value decomposition (QSVD) are utilized to decompose the HDR image for obtaining robust features, which is fused with a binary watermark to generate a zero watermark for copyright protection. Furthermore, the binary watermark is scrambled for the security by using the Arnold transform. Experimental results denote that the proposed zero-watermarking method is robust to TM and other image processing attacks, and can protect the HDR image efficiently.

A Novel Zero Watermarking Based on DT-CWT and Quaternion for HDR Image

The biggest challenge of texture filtering is to smooth the strong gradient textures while maintaining the weak structures, which is difficult to achieve with current methods. Based on this, we propose a scale-adaptive texture filtering algorithm in this paper. First, the four-directional detection with gradient information is proposed for structure measurement. Second, the spatial kernel scale for each pixel is obtained based on the structure information; the larger spatial kernel is for pixels in textural regions to enhance the smoothness, while the smaller spatial kernel is for pixels on structures to maintain the edges. Finally, we adopt the Fourier approximation of range kernel, which reduces computational complexity without compromising the filtering visual quality. By subjective and objective analysis, our method outperforms the previous methods in eliminating the textures while preserving main structures and also has advantages in structure similarity and visual perception quality.

/pdf/adaptive-bilateral-texture-filter-for-image-smoothing-3j4novt6.pdf

Adaptive Bilateral Texture Filter for Image Smoothing

High dynamic range image (HDRI) which is combined with low dynamic range image (LDRI) needs to be mapped to a low dynamic area to display. In the process of mapping, it is impossible to determine t...

A Contribution Algorithm from LDRI to HDRI

Tone mapping operators are designed to display high dynamic range (HDR) images on low dynamic range devices. Clustering-based content and color adaptive tone mapping algorithm aims to maintain the color information and local texture. However, fine details can still be lost in low dynamic range images. This paper presents an effective way of clustering-based content and color adaptive tone mapping algorithm by using fast search and find of density peak clustering. The suggested clustering method reduces the loss of local structure and allows better adaption of color in images. The experiments are carried out to evaluate the effectiveness and performance of proposed technique with state-of-the-art clustering techniques. The objective and subjective evaluation results reveal that fast search and find of density peak preserves more textural information. Therefore, it is most suitable to be used for clustering-based content and color adaptive tone mapping algorithm.

/pdf/personal-communication-technologies-for-smart-spaces-density-2zl6wc2p9z.pdf

Personal Communication Technologies for Smart Spaces Density-Based Clustering for Content and Color Adaptive Tone Mapping

The recognition rate of computer vision algorithms is highly dependent on the image quality. To enhance the visual quality of the images captured under high-dynamic range (HDR) scenes, we propose a...

Yuan Jia

Papers

Efficient and Adaptive Tone Mapping Algorithm Based on Guided Image Filter