Adaptive Ordered Dither

Zhang, Yuefeng

doi:10.1006/gmip.1996.0414

Cited by 9 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering security of the method, presence of only one share image reveals nothing about the corresponding secret image, i.e., each 2*2 pixels block of one share-image may correspond to either a white pixel or a black pixel of the secret image. As Figure 2 shows, stacking the shares of a black secret pixel results in 4 black sub pixels, whereas only 2 black sub pixels is gained by stacking shares of a white secret pixel [40]. So, secret image is revealed to human eyes by stacking the shares without performing any cryptographical co mputations.…”

Section: Visual Cryptographymentioning

confidence: 99%

Multiple Watermarking Scheme for Image Authentication and Copyright Protection using Wavelet based Texture Properties and Visual Cryptography

Radharani¹,

Valarmathi²

2011

IJCA

View full text Add to dashboard Cite

Advancement in communication medium is producing large volume of digital information which needs to be protected. Watermarking is a technique that is used to hide secret signal into digital signal in a manner that does not reduce overall quality of the original signal. In relation to digital image watermarking, another area that is drawing attention is the multiple watermarking, where more than one watermark is embedded into single multimedia object. M ultiple watermarks are normally proposed as a method to provide extra security to an image by embedding two or more secret messages into the cover image. In the present research work, the concept of multiple watermarking is used to hide both copyright and authentication information into a color image. For this purpose a wavelet transformation based on texture properties and secret sharing us ing visual cryptography is used. Experimental results indicate that the proposed watermarking scheme is highly robust and does not degrade the original signal.

show abstract

Section: Visual Cryptographymentioning

confidence: 99%

Multiple Watermarking Scheme for Image Authentication and Copyright Protection using Wavelet based Texture Properties and Visual Cryptography

Radharani¹,

Valarmathi²

2011

IJCA

View full text Add to dashboard Cite

show abstract

“…Larger size halftone cells can be used for the rendering of smooth regions such as backgrounds to improve the tonal resolution and smaller size cells can be employed at spatially varying regions such as edges to increase the spatial resolution. This image adaptive approach is adopted in [28] and [29] by varying the size of the dither matrices depending on the changes in image values along the scanning path of a space filling curve. In [30], Hel-Or et al developed a similar iterative halftoning scheme, wherein the halftone cells vary in size and shape based on a spatial "busyness" metric for the image.…”

Section: Related Workmentioning

confidence: 99%

Continuous Phase-Modulated Halftones

Oztan

Sharma

2009

IEEE Trans. on Image Process.

View full text Add to dashboard Cite

Abstract-A generalization of periodic clustered-dot halftones is proposed, wherein the phase of the halftone spots is modulated using a secondary signal. The process is accomplished by using an analytic halftone threshold function that allows halftones to be generated with controlled phase variation in different regions of the printed page. The method can also be used to modulate the screen frequency, albeit with additional constraints. Visible artifacts are minimized/eliminated by ensuring the continuity of the modulation in phase. Limitations and capabilities of the method are analyzed through a quantitative model. The technique can be exploited for two applications that are presented in this paper: a) embedding watermarks in the halftone image by encoding information in phase or in frequency and b) modulating the screen frequency according to the frequency content of the continuous tone image in order to improve spatial and tonal rendering. Experimental performance is demonstrated for both applications.

show abstract

“…Recently another similar approach was suggested. 16 In Ref. 14 a tessellation of the image plane was produced using a quadtree structure which recursively divides the image into quadrants.…”

Section: Previous Workmentioning

confidence: 99%

Adaptive cluster dot dithering

Hel‐Or

Zhang

Wandell

1999

J. Electron. Imaging

View full text Add to dashboard Cite

Cluster dot dithering is one of the most common halftoning techniques. It is fast, low in complexity and allows for variability and inconsistencies in point spreads in printer outputs. Determination of the basic dither cell size is critical for the quality of the halftoning. There is a basic tradeoff between large and small cell sizes: spatial resolution versus gray tone resolution. Large dither cell sizes produce good tone resolution but poorly reproduce spatial details in the image. Small dither cells, on the other hand, produce fine spatial resolution but lack the tone resolution which produces smooth gray tone gradients in halftone images. Typically, cluster dot dithering assumes a predefined dither cell size that compromises between fine detail reproduction and good gray tone reproduction. It is clearly advantageous to allow variability in the dither cell size using small cell sizes in image regions of fine details and using large cell sizes in image regions where gray tones are to be accurately reproduced. In this paper, we introduce and discuss several adaptive dithering techniques based on cluster dot dithering.

show abstract

Adaptive Ordered Dither

Cited by 9 publications

References 8 publications

Multiple Watermarking Scheme for Image Authentication and Copyright Protection using Wavelet based Texture Properties and Visual Cryptography

Multiple Watermarking Scheme for Image Authentication and Copyright Protection using Wavelet based Texture Properties and Visual Cryptography

Continuous Phase-Modulated Halftones

Adaptive cluster dot dithering

Contact Info

Product

Resources

About