Implementation and performance study of image data hiding/watermarking schemes

Two data hiding / watermarking techniques for grayscale and color images are presented. One of them is DCT based, another uses DFT to embed data. Both methods were implemented in software utilizing C/C++. The complete listings of these programs are included. A comprehensive reliability analysis was performed on both schemes, subjecting watermarked images to JPEG, SPIRT and MPEG-2 compressions. In addition, the pictures were examined by exposing them to common signal processing operations such as image resizing, rotation, histogram equalization and stretching, random, uniform and Gaussian noise addition, brightness and contrast variations, gamma correction, image sharpening and softening, edge enhancement, manipulation of a channel bit number and others. Methods were compared to each other. It has been shown that the DCT method is more robust and, hence, suitable for watermarking purposes. The DFT scheme exhibits less robustness, but due to its higher capacity is perfect for data hiding purposes

An Overview on Image Forensics

The aim of this survey is to provide a comprehensive overview of the state of the art in the area of image forensics. These techniques have been designed to identify the source of a digital image or to determine whether the content is authentic or modified, without the knowledge of any prior information about the image under analysis (and thus are defined as passive). All these tools work by detecting the presence, the absence, or the incongruence of some traces intrinsically tied to the digital image by the acquisition device and by any other operation after its creation. The paper has been organized by classifying the tools according to the position in the history of the digital image in which the relative footprint is left: acquisition-based methods, coding-based methods, and editing-based schemes

Robust Watermarking Schemes for Digital Images

With the rapid development of multimedia and the widespread distribution of digital data over the internet networks, it has become easy to obtain the intellectual properties. Consequently, the multimedia owners need more than ever before to protect their data and to prevent their unauthorized use. Digital watermarking has been proposed as an effective method for copyright protection and an unauthorized manipulation of the multimedia. Watermarking refers to the process of embedding an identification code or some other information called watermark into digital multimedia without affecting the visual quality of the host multimedia. Such a watermark can be used for several purposes including copyright protection and fingerprinting of the multimedia for tracing and data authentication. The goal in a watermarking scheme is to embed a watermark that is robust against various types of attacks while preserving the perceptual quality of the cover image. A variety of schemes have been proposed in the literature to achieve these goals for watermarking of images. These schemes either provide good imperceptibility of the watermark without sufficient resilience to certain types of attacks or provide good robustness against attacks at the expense of degraded perceptual quality of the cover images. The objective of this work is to develop image watermarking schemes with performance that is superior to those of existing schemes in terms of their robustness against various types of attacks while preserving the perceptual of the cover image. In this thesis, two new digital image watermarking schemes are proposed. In the first scheme, an Arnold transform integrated DCT-SVD based image watermarking scheme is developed. The main idea in this scheme is to improve the robustness of the watermarking further by scrambling the watermark data using the Arnold transform while still preserving the good perceptibility of the watermarked image furnished by a DCT-SVD based embedding. Also, it is shown that considerable savings in the computation time to recover the original watermark image can be provided by using the anti-Arnold transform in the watermark extraction process. In the second scheme, a DWT-SVD digital image watermarking scheme that makes use of visual cryptography to embed and extract a binary watermark image is developed. The use of visual cryptography in the proposed watermarking scheme is intended to provide improved robustness against attacks along with furnishing security to the content of the embedded data. Extensive experiments are conducted throughout this investigation in order to examine the performance of the proposed watermarking schemes. It is shown that the two proposed watermarking schemes developed in this thesis provide a performance superior to that of the existing schemes in terms of robustness against various types of attacks while preserving the perceptual quality of the cover image

CleanPage: Fast and Clean Document and Whiteboard Capture

The move from paper to online is not only necessary for remote working, it is also significantly more sustainable. This trend has seen a rising need for the high-quality digitization of content from pages and whiteboards to sharable online material. However, capturing this information is not always easy nor are the results always satisfactory. Available scanning apps vary in their usability and do not always produce clean results, retaining surface imperfections from the page or whiteboard in their output images. CleanPage, a novel smartphone-based document and whiteboard scanning system, is presented. CleanPage requires one button-tap to capture, identify, crop, and clean an image of a page or whiteboard. Unlike equivalent systems, no user intervention is required during processing, and the result is a high-contrast, low-noise image with a clean homogenous background. Results are presented for a selection of scenarios showing the versatility of the design. CleanPage is compared with two market leader scanning apps using two testing approaches: real paper scans and ground-truth comparisons. These comparisons are achieved by a new testing methodology that allows scans to be compared to unscanned counterparts by using synthesized images. Real paper scans are tested using image quality measures. An evaluation of standard image quality assessments is included in this work, and a novel quality measure for scanned images is proposed and validated. The user experience for each scanning app is assessed, showing CleanPage to be fast and easier to use

Enhancement of Digital Photo Frame Capabilities With Dedicated Hardware

Photo frames have come a long way since the typical ones that needed to have a photo printed and stuck on them. Today in this digital era we have a new concept, named digital photo frame, a modern representation of the conventional photo frame. A digital photo frame is basically a picture frame that displays photos without the need to print them. They are available in a variety of sizes and with varied configurations. A typical frame varies in size from 7 inches to 20 inches. There are also key chain sized frames available. These frames also support a variety of formats like .jpeg, .tiff, .bmp and so on. Most of the frames provide an option to run the photos in a sequential or random manner as a slideshow with an adjustable time interval. The mode of input of the photos to the frame is also multi-fold. It can be done directly via the memory card of the camera, or else various memory devices like USB drives, SD Cards, MMC Cards and so on can be used. Nowadays even Bluetooth technology is being used. Another option that is becoming quite popular is that, users can take their photos directly from the Internet from sites like Flickr, Picassa or from their e-mail. Also these frames generally come with built in speakers and with remote controls. Our initial objective was to decide on which all features can be added to the Digital Photo Frame that we design. For this purpose we conducted simulation exercises in MATLAB so as to prove its feasibility. This simulation exercise was divided into two parts. The first part was to perform compression and decompression and the second half dealt with the various enhancements that can be added to the frame. For our compression and decompression we considered the JPEG standard. Joint Photographic Experts Group - an ISO/ITU standard for compressing still images. The JPEG format is very popular due to its variable compression range. A few limitations of JPEG include the fact that it is lossy and also not great for displaying text. The common extension for it include *.jpg, *.jff, *.m-jpeg,*.mpeg The various enhancement features that we tested for feasibility include Mean Filter, Median Filter, Image Sharpening, Negative Image Extraction, Logarithmic Transformations, Power Law Correction (Gamma Correction), Contrast Stretching, Grey Level Slicing, Bit Plane Slicing, Laplace Filtering. We then proceeded onto the hardware implementation of the above said features. We only implemented a handful of features owing to the complexity of design and lack of time. We first implemented the Compression and Decompression algorithm. The two enhancement features we implemented were Laplace Filter and Median Filter. For our implementation we used the VIRTEX 2 FPGA Board

Common Imaging Problems

A presentation given at The Library in Bits and Bytes: Digital Library Symposium, held at the University of Maryland on 29 September 2005

BCR’s CDP Digital Imaging Best Practices, Version 2.0

This is the published version.These Best Practices — also referred to as the CDP Best Practices -- have been created through the collaboration of working groups pulled from library, museum and archive practitioners. Version 1 was created through funding from the Institute for Museum and Library Services through a grant to the University of Denver and the Colorado Digitization Program in 2003. Version 2 of the guidelines were published by BCR in 2008 and represents a significant update of practices under the leadership of their CDP Digital Imaging Best Practices Working Group. The intent has been to help standardize and share protocols governing the implementation of digital projects. The result of these collaborations is a set of best practice documents that cover issues such as digital imaging, Dublin Core metadata and digital audio. These best practice documents are intended to help with the design and implementation of digitization projects. Because they were collaboratively designed by experts in the field, you can be certain they include the best possible information, in addition to having been field tested and proven in practice. These best practice documents are an ongoing collaborative project, and LYRASIS will add information and new documents as they are developed

SOW: Digitization and longterm preservation of weather maps at ZAMG

The targets of this concept are: delivering a catalog of requirements; the evaluation of tools; possible file formats (e.g. FITS) necessary for digitization and longtime preservation of the historical weather maps at ZAMG (Central Institute for Meteorology and Geodynamics, Austria's national weather and geophysical service