نتایج جستجو برای: halftone
تعداد نتایج: 479 فیلتر نتایج به سال:
In the second half of nineteenth century, Portugal undertook in its mainland and colonial territories an ambitious modernising programme based on technoscientific grounds. From late 1870s onwards, such was widely advertised Occidente, most important illustrated journal time that published several drawings original photographs. this paper, I will analyse imagery authentic photography related to ...
A halftoning technique that uses a simple GA has proven to be very effective to generate high quality halftone images. Recently, the two major drawbacks of this conventional halftoning technique with GAs, i.e. it uses a substantial amount of computer memory and processing time, have been overcome by using an improved GA (GA-SRM) that applies genetic operators in parallel putting them in a coope...
Visual cryptography encodes a secret binary image (SI) into shares of random binary patterns. If the shares are xeroxed onto transparencies, the secret image can be visually decoded by superimposing a qualified subset of transparencies, but no secret information can be obtained from the superposition of a forbidden subset. The binary patterns of the shares, however, have no visual meaning and h...
Extended Visual Cryptography (EVC) concept provides meaningful shares instead of non meaningful shares. In this paper we proposed an algorithm based on EVC which enhances the contrast of the recovered secret image. Here the size of image visible on shares is taken to be three times as that of secret image, both the images are assumed in grey level. In the proposed algorithm secret image and the...
Halftones and other binary images are difficult to process with causing several degradation. Degradation is greatly reduced if the halftone is inverse halftoned (converted to grayscale) before scaling, sharpening, rotating, or other processing. For error diffused halftones, we present (1) a fast inverse halftoning algorithm and (2) a new multiscale gradient estimator. The inverse halftoning alg...
A novel verifiable secret sharing method for Verifiable secret sharing (VSS) in halftone image based on linear block code with a parity check matrix is proposed. The proposed method, which not only verifies a secret image but also introduces multiple shadows for multiple users. The proposed method adopts forward error correction code (FEC) strategy based on property of linear block codes. There...
In this paper, a least distortion approach is proposed for halftone image watermarking. The impacts of distortion and tonality problems in halftoning are analyzed. An iterative linear gain model is developed to optimize perceptual quality of watermarking halftone images with efficient computation complexity O(1). An optimum linear gain for data hiding error diffusion is derived and mapped into ...
Today steganography has attracted the attention of many researchers. In this paper, we propose a new steganography method for secure Data communication on half tone pictures. Using the halftone pictures improve the security and capacity. In this method, the complexity of every pixel in picture is computed, then a neibourhood is defined to compute the complexity of every pixel, and then the comp...
We suggest an optimization-based method for halftoning that involves looking ahead before a decision for each binary output pixel is made. We first define a mixture distortion criterion that is a combination of a frequency-weighted mean square error (MSE) and a measure depending on the distances between minority pixels in the halftone. A tree-coding approach with the ML-algorithm is used for mi...
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