Computing Voronoi diagrams in digital pictures

The 4-metric is adopted to construct the Voronoi diagram of a binary digital picture, whose foreground consists of arbitrarily shaped components. The 4-distance transform of the background is employed to find the exoskeleton, from which the set of the Voronoi edges is succesivvely obtained after removal of certain pixels. As an ultimate step, the various tiles are identified by using a component labeling technique. The proposed algorithm can be convenietly implemented on standard sequential computers, as only five complete inspections of the picture are sufficient for the whole process. Moreover, all the computations are performed on the array where the picture is initially stored.     

An algebraic description of painted digital pictures

An algebraic system for binary digital pictures has already been described, along with the definition of the four arithmetic rules. In this paper, an extension of the binary algebraic system to a 2n-valued one is first proposed. It then becomes evident that this extended algebraic system satisfies several properties including those of a ring. An example of a 2n-valued model, an eight-valued algebraic system, is introduced and applied to painted digital pictures. Pictorial operations such as multiple arrangement, enlargement, differentiation, integration, and color changes are then dealt with by the combinations of the four arithmetic rules.     

A criterion on thinning in digital pictures

Letp = (²,m,n,B) be a two-dimensional digital picture, where adjacency (m, n) is (4,8), (8,4) or (6,6). We give the conditions for obtaining those points which can be deleted inp, preserving the topology type. In particular, the connectivity and Euler's characteristics of the picture remain unchanged.The necessary computations for the implementation of this deletion procedure are, to a great extent, simplified with respect to the results known up to now, since it is not necessary to explicitly obtain the simple points of the two-dimensional digital picture.     

Processing noisy line spectrograms as digital pictures

Contiguous short-term spectral estimates of non-stationary acoustic signals are often displayed as intensity-modulated frequency-time pictures (‘spectrograms’). Some of the problems and advantages in storing and processing certain types of spectrograms as digital pictures are explored. The particular type of spectrogram discussed is from a source producing a time-variant ‘line’ spectrum consisting of one dominant primary line and several much weaker harmonic or quasi-harmonic lines. This type of spectrogram is commonly produced by rotating machinery. It is supposed that this signal is measured amidst additive broad band noise. The resulting spectrogram consists of a family of related meandering lines, the weaker members of which tend to be lost in the noise. In the proposed picture analysis scheme the raw spectral estimates are stored as a digital spectrogram. This spectrogram is then processed by line enhancement methods to extract the primary line to form a ‘family-template’. Using this template the weaker lines can be detected and extracted. By re-assembling the extracted components, a cleaned-up low-entropy frequency-time picture of the signal is produced which shows more structure and which is much more amenable to automatic analysis than the original spectrogram.     

Detection of interlocking components in three-dimensional digital pictures

An interlocking component in three-dimensional (3D) digital pictures is defined. It is proved that no one-pebble acceptor can detect interlocking components in a 3D digital picture.     

Color-secure digital image compression

Multimedia Tools and Applications - The wide spread acquisition and use of ultra-high resolution color images obtained from high-resolution imaging sensors introduces open problems of optimal...     

Pixel distribution shifting color correction for digital color images

This paper is concerned with a proposed color correction method called the Pixel Distribution Shifting Color Correction (PDSCC). This method employs a shifting process on the pixel distribution of a color image to correct its white reference point and ensure the white reference point is achromatic. The proposed method has been tested on numerous types of images which include indoor, outdoor, and underwater images. The qualitative and quantitative analyses have shown ample evidence that the proposed method outperforms some state-of-the-art methods, such as the Grey World, the White Patch and the General Grey World methods. The resultant images are viewed to be more natural and suggest more pleasant visualization without the intervention of the saturation problem.     

基于H.264的静止自由立体图像压缩算法

针对静止自由立体图像数据量大的问题,摆脱了传统以JPEG标准进行静止图像压缩的思路,根据视点数不同,选择了相应的关键视点编码为I帧,其余的分别编码为P帧和B帧,充分利用了H.264的帧内、帧间预测等工具对其进行压缩。实验结果表明,基于H.264的压缩算法比基于MPEG-2、JPEG的压缩算法效率更高、图像自由立体效果更好。     

A general approach to parameter evaluation in fuzzy digital pictures

A general approach to the evaluation of parameters from fuzzy regions is outlined. The main idea is to consider a fuzzy subset of an images as the nested family of its level-cuts, interpret this family as a body of evidence in the sense of Shafer. Any intrinsic parameter can then be calculated as a mathematical expectation based on a probability density function. Fuzzy-valued parameters can also be derived. The approach encompasses recent proposals by Rosenfeld for specific parameters such as perimeter, diameter, etc., as well as the cardinality of a fuzzy set. It is also extended to relational parameters between fuzzy regions in the image.     

Processing spectrograms as digital pictures to separate competing line signatures

The problem of extracting individual signatures from a (digital) spectrogram containing two or more line signatures amidst random noise is discussed. It is assumed that each signature family contains a dominant line and the method proposed is based on using line enhancement and grouping procedures to isolate these dominant components. Using the extracted lines, a family of two-dimensional matched filters are designed for each signature and used to detect the weaker members of the family. Cleaned-up low-entropy spectrograms of each source can then be produced.     

基于矢量量化的数字视频压缩技术

对基于矢量量化的数字视频压缩技术进行了论述，并根据分析结果提出了一种新的矢量量化算法——多级矢量量化联合编码算法，该算法保持了多级矢量量化算法编码速度快、图像相关性小等特点，同时提高了编码质量。实验表明，该算法与已有的算法相比具有较高的图像质量和更高的压缩率。     

An optimal frequency domain filter for edge detection in digital pictures

Edge detection and enhancement are widely used in image processing applications. In this paper we consider the problem of optimizing spatial frequency domain filters for detecting edges in digital pictures. The filter is optimum in that it produces maximum energy within a resolution interval of specified width in the vicinity of the edge. We show that, in the continuous case, the filter transfer function is specified in terms of the prolate spheroidal wave function. In the discrete case, the filter transfer function is specified in terms of the sampled values of the first-order prolate spheroidal wave function or in terms of the sampled values of an asymptotic approximation of the wave function. Both versions can be implemented via the fast Fourier transform (FFT). We show that the optimum filter is very effective for detecting blufred and noisy edges. Finally, we compare the performance of the optimum edge detection filter with other edge detection filters using a variety of input images.     

Analysis of color difference in digital proofing based on color management system

Managing and controlling color is a major concern for the imaging industry. The aim of the investigation was to identify the color difference that exists in the color patches in a typical color reproduction workflow. After the calibration, characterization and conversion of all the devices （Microtek scanmaker8700, Apple CRT and EPSON stylus pro 7800） using GretagMacbeth Profilemaker 5.05 software and X-Rite Eye-one spectrophotometer, the color gamut of the devices were inspected with ColorThink software for profile accuracy. Based on the results obtained by spectrophotometer measurements, the reproduction quality of specially color patches was evaluated in terms of the AE in CIEL＊a＊b＊ color space. The analysis shows the color difference that exists in digital proofing and the results can be significant to acquire flexibility over colors in reproducing images.     

Motion estimation based color transfer and its application to color video compression

In this paper a novel scheme for color video compression using color transfer technique is proposed. Towards this, a new color transfer mechanism for video using motion estimation is presented. Encoder and decoder architectures for the proposed compression scheme are also presented. In this scheme, compression is achieved by firstly discarding chrominance information for all but selected reference frames and then using motion prediction and discrete cosine transform (DCT) based quantization. At decompression stage, the luminance-only frames are colored using chrominance information from the reference frames applying the proposed color transfer technique. To integrate color transfer mechanism with hybrid compression scheme a new color transfer protocol is defined. Both compression scheme and color transfer work in YCbCr color space.

Automated event clustering and quality screening of consumer pictures for digital albuming

In this paper, algorithms for automatic albuming of consumer photographs are described. Specifically, two core algorithms namely event clustering and screening of low-quality images, are introduced and their performance is evaluated. Event clustering and image quality screening have many applications including albuming services, image management and organization, and digital photofinishing. These are difficult tasks because there is, in general, none (or very limited) contextual information about picture content, and the final interpretation could be subjective. A novel event-clustering algorithm is created to automatically segment pictures into events and subevents for albuming, based on date/time metadata information, as well as color content of the pictures. A block-based color histogram correlation technique is developed for image content comparison of general consumer pictures. A new quality-screening algorithm is developed based on object quality measures, to detect problematic images caused by underexposure, low contrast, and camera defocus or movement.     

Efficient axis-translation of binary digital pictures by blocks in linear quadtree representation

For binary digital pictures with large all-black fragments, the linear quadtree representation is a space-efficient data structure on which many time-efficient algorithms, such border-determination and filling, have been implemented. Translation—moving the picture bodily in a fixed direction—was originally done by converting each pixel into bit-map form. More recently, a recursive translation-rotation algorithm has appeared which makes better use of the hierarchical nature of the data structure, together with a time-complexity bound expressed in terms of the output. We present a nonrecursive translation algorithm with the same asymptotic worst-case time-complexity bound as the recursive algorithm, but which turns out to execute significantly faster than either of the previous algorithms. We generalize this algorithm to higher dimensional pictures, and we express the time-complexity in terms of the input data.     

“Probability transforms” of digital pictures

Let g be any local property (e.g., gray level or gradient magnitude) defined on a digital picture. Let p_g(z) be the relative frequency with which g has value z. At each point (x,y) of the picture we can display p_g[g(x,y)], appropriately scaled; the result is called the p_g transform of the picture. Alternatively, we can use joint or conditional frequencies of pairs of local properties to define transforms. This note gives examples of such transforms for various gs and discusses their possible uses and limitations.     

Erratum to: Color-secure digital image compression

Multimedia Tools and Applications -     

A novel quantum representation of color digital images

In this paper, we propose a novel quantum representation of color digital images (NCQI) in quantum computer. The freshly proposed quantum image representation uses the basis state of a qubit sequence to store the RGB value of each pixel. All pixels are stored into a normalized superposition state and can be operated simultaneously. Comparison results with the latest multi-channel representation for quantum image reveal that NCQI can achieve a quadratic speedup in quantum image preparation. Meanwhile, some NCQI-based image processing operations are discussed. Analyses and comparisons demonstrate that many color operations can be executed conveniently based on NCQI. Therefore, the proposed NCQI model is more flexible and better suited to carry out color quantum image processing.