Hue-Preserving Saturation Improvement in RGB Color Cube

This paper proposes a method for improving saturation in the context of hue-preserving color image enhancement. The proposed method handles colors in an RGB color space, which has the form of a cube, and enhances the contrast of a given image by histogram manipulation, such as histogram equalization and histogram specification, of the intensity image. Then, the color corresponding to a target intensity is determined in a hue-preserving manner, where a gamut problem should be taken into account. We first project any color onto a surface in the RGB color space, which bisects the RGB color cube, to increase the saturation without a gamut problem. Then, we adjust the intensity of the saturation-enhanced color to the target intensity given by the histogram manipulation. The experimental results demonstrate that the proposed method achieves higher saturation than that given by related methods for hue-preserving color image enhancement.

Implementation of Steganographic Algorithms Based on Exact Histogram Matching and Colour Visual Cryptography

Sensitive secret data transmission through internet has been of great security concern which can be overcome by steganographic methods achieved through secret image sharing. Two novel steganographic secret algorithms based on colour visual cryptography and exact histogram specification is proposed in the present study. The former approach combines colour visual cryptography with a secret key to produce less distorted meaningful share images. A specified histogram acts as the key for the second approach and provides better security and data obscurity compared to conventional approaches. A novel histogram specification method is also proposed which exactly matches the histogram of an image to a specified histogram