Half Toning Research Articles

Dithering techniques and segmentation analysis on a mammogram breast cancer image

The objective of the publishing industry is to minimize the number of colors in an image for printing. Also, to retain the better quality from the picture, some useful techniques are needed with the aid of only a few colors. The contouring consequences occur when an image quantized bluntly regardless of the quantization, either uniform or non-uniform. To alleviate the issues of contouring, a slight amount of random noise is added (dithered) to the original image, followed by the quantization method. The methods such as dithering and half toning are extensively used strategies in acquiring texts and pictures in books, newspapers, magazines, computer monitors, and LCDs. This article investigates the dithering technique on a mammogram image with different procedures, such as dithering followed by quantization and dithering, quantization followed by filtering are detailed with Mean Square Error (MSE) and Peak Signal-to-Noise Ratio (PSNR) results. For better visualization, segmentation techniques are applied to the dithering technique.

CMY Color Spaced-Based Visual Cryptography Scheme for Secret Sharing of Data

Visual cryptography technique allows visual information to be encrypted in such a way that the decrypted information appears as a visual image. Visual cryptography allows digital images to be separate into few shares called transparent shares. For security reasons, it ensures that hackers cannot find any clues about the secret image from a single cover image. The proposed technique uses CMY (cyan, magenta, yellow) color space to enhance visual cryptography, and mean visual cryptography can be used on color images. The other techniques used were color decomposition and error diffusion. Error diffusion is a type of half toning in which the quantization residual is distributed to neighboring pixels that have not yet been processed. The image will be encrypted by four shares which is cyan, magenta, yellow, and mask. Mask will be using random function to random generate half black and half white pixel in 2 × 2 block. Stack all the shares for reviewing the secret image. After that, do the image preprocessing of the image and use OCR (optical character recognition) to recognize the message.

Hierarchical threshold secret sharing scheme for color images

The applications that use pattern recognition via secret sharing are seldom linear, straightforward and uncomplicated. The layers of complexity grows as the process turns more secretive. In applications, such as banking transactions, hierarchical secret sharing comes in as a handy tool. This paper analyses the use of disjunctive hierarchy of secret sharing without compromising security while saving time. This scheme simplifies the process when more hands are involved by using simple Boolean and arithmetic operations and thus reduces the computational complexity from O (nlog2n) to O (n). The other features are authentication of the participants using Lagrange Interpolation; non-requirement of half toning of color images; no pixel expansion without degradation in visual quality of the recovered secret image. This paper also provides solution for meaningful share images with the ability to detect the manipulation of share images. The main advantage of this scheme is that it gives the benefit in scenarios in which participants of different levels are involved.

Error Diffusion Using Half Toning in Color Images

In this paper, a new error diffusion method is proposed that provides high quality ED results. The goal of half-toning method is to quantize each pixel to one bit binary pixel. The proposed error diffusion method is based on half toning method, which is known as Floyd and Steinberg’s filter. To expedite processing time, the denominator of the proposed method is chosen in 2k form, where k is integer number. Therefore, the method is faster than the previous methods, while preserving simplicity. Experimental results show that the obtained red, green, blue channels and color images look satisfactory for viewer.

Halftoning by Error Diffusion Method in Visual Cryptography for Greyscale Image

Visual Cryptography (VC) is a technique used for protecting image based secrets. The main concept of the original visual cryptography scheme is to encrypt a secret image into some shares. Secret information cannot be revealed with few shares. All shares are necessary to combine to reveal the secret image. Halftoning is the important feature of visual cryptography. It provides security at the early stage of visual cryptography. Halftoning is the reprographic techniques, whose process of converting large tone (high intensity value of pixel) image to low tone (low intensity value of pixel) image. The visual cryptography is a hide information technology. The visual cryptography uses sharing method apply for hide information. Here used the (2, 2) greyscale image method, 2 shares out of 2 stack the secret will reveal and less than 2 shares are not work. Here, proposed a modified algorithm of error-diffusion half toning in visual cryptography. Increment the quality of image by modified method according to different parameters. According to modified method, error distributed to nearest pixel. The compared author method with Floyed, Jarvis, and Stucki throw PSNR and UQI parameters. The visual secret scheme decrypts the secret image using Human Visual System (HVS) without any computation. Here, used to (2, 2) generate visual sharing system for halftone gray scale image. Here generate shares of halftone image and recovered secret image.

Threshold Secret Sharing Scheme for Compartmented Access Structures

In the realm of visual cryptography, secret sharing is the predominant method of transmission and reception of secure data. Most of the (n, n) secret sharing schemes suffer from one common flaw — locking of information when the all- n number of receivers are not available for some reason. This paper proposes a new method of compartmented secret sharing scheme where some threshold number of equally privileged from each compartment can retrieve data. This scheme rules out regeneration of secret image at the single compartment thereby eliminating the danger of misusing secret image. The key features of this scheme are: better visual quality of the recovered image with no pixel expansion; non-requirement of half toning of color images; less computational complexity by reconstructing secret through XORing and simple addition of all share images. This scheme is highly beneficial in applications where data has to be stored securely in a database and in cloud computing to synchronize information passed to different groups or clusters from a single host.

Data Compression for Video-Conferencing using Half tone and Wavelet Transform

Overhead of data transmission over internet is increasing exponentially every day. Optimization of natural bandwidth is the basic motive by compressing image data to the maximum extend. For the same objective, combination of lossy half tone and lossless Wavelet Transform techniques is proposed so as to obtain low-bit rate video data transmission. Decimal values of bitmapped image are to be converted into either 1 or 0 in half toning process that incur pictorial loss and gives 8:1 compression ratio (CR) irrespective of image. Wavelet Transform is applied on half tone image for higher compression for various levels. An experimental result shows the higher CR, minimum Mean Square Error (MSE). Ten sample images of different people captured by Nikon camera are used for experimentation. All images are bitmap (.BMP) 512 X 512 in size. The proposed technique can be used for video conferencing, storage of movies and CCTV footage etc.

Image Reconstruction using Fast Inverse Half tone and Huffman Coding Technique

Transmission of audio-video data over internet applications like Multimedia is increasing with fast pace. Biometric, Content Based Image Retrieval (CBIR), CCTV footage applications require huge storage of images in database. For such applications this combination of half tone with Huffman coding is useful. Half toning is lossy technique used in printing industry where binary image is required. Objective of achieving higher Compression Ratio by combining lossy half tone and lossless Modified Huffman coding techniques is used. Apart from standard operator like Floyd-Steinberg and Jarvis operators, Small and South-East operator are used. Halftone and Huffman coding technique is implemented on 10 different color images of size 512x512. For measurement of image quality, Mean Square Error (MSE) and Peak Signal-to-Noise Ratio (PSNR) and Structure Similarity Index (SSIM) are used. This hybrid technique can use for low bit rate video data transmission and mass image storage.

High‐quality multilevel error diffusion method employing variable threshold

AbstractWe propose a new multilevel error diffusion method employing a variable threshold, which realizes half toning with high quality. In the proposed method, dissimilar textures around quantization levels, which are the cause of the low image quality obtained by conventional methods, are decreased by using the variable threshold. In this paper, we apply the proposed method to various standard digital images. Simulation results show that the method is superior to other multilevel error diffusion methods. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(2): 25–33, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10373

High-quality Multi-level Error Diffusion Method Employing Fuzzy Inference

We propose a new multi-level error diffusion method employing the fuzzy inference, which realizes half toning with high quality. In the proposed method, dissimilar textures around quantization levels, which are the cause of the low image quality and obtained by a conventional method, are decreased by using fuzzy inference. In this paper, we apply the proposed method to various standard digital images. The image quality of the result using the proposed method is higher than those of other methods without noise-add filtering, and it is almost same as them with filtering in 2 or 3 times faster processing.

High Quality Multi-level Error Diffusion Method Employing Variable Threshold

We propose a new multi-level error diffusion method employing the variable threshold, which realizes half toning with high quality. In the proposed method, dissimilar textures around quantization levels, which are the cause of the low image quality and obtained by a conventional method, are decreased by using the variable threshold. In this paper, we apply the proposed method to various standard digital images. And the simulation results show that the method is superior to other multi-level error diffusion methods.