Scan Conversion Algorithm Research Articles

Stochastic Rounding for Image Interpolation and Scan Conversion

The stochastic rounding (SR) function is proposed to evaluate and demonstrate the effects of stochastically rounding row and column subscripts in image interpolation and scan conversion. The proposed SR function is based on a pseudorandom number, enabling the pseudorandom rounding up or down any non-integer row and column subscripts. Also, the SR function exceptionally enables rounding up any possible cases of subscript inputs that are inferior to a pseudorandom number. The algorithm of interest is the nearest-neighbor interpolation (NNI) which is traditionally based on the deterministic rounding (DR) function. Experimental simulation results are provided to demonstrate the performance of NNI-SR and NNI-DR algorithms before and after applying smoothing and sharpening filters of interest. Additional results are also provided to demonstrate the performance of NNI-SR and NNI-DR interpolated scan conversion algorithms in cardiac ultrasound videos.

RETRACTED ARTICLE: Simulation of coastal beach stability and coastal running based on embedded image system

Approximately 80% of the sandy beaches along the coastline have been eroded, resulting in the coarsening, narrowing of sandy beaches, steeper slopes, accelerated shoreline retreat, loss of a large amount of coastal land, and destruction of the ecological environment. Coastal beach stability assessment technology, through more than 1 year of field data observation, the stability analysis of the coastal beaches, from the observations of various data shows that the coastal beaches are in a dynamic and stable equilibrium state during the measurement period; around the beach, there is no large-scale erosion and accumulation. Moreover, because society is progressing, people’s concept of life is also constantly changing, and the requirements for health are also constantly improving. People have begun to advocate sports, and running has become people’s main sport due to its low economic cost and convenience. In this way, even many people who have no experience in running start to run. However, due to the constraints of the runners’ physical fitness and the surrounding sports environment and other objective conditions, coupled with the current running styles and even insufficient research on the prevention of injuries during the running process, they cannot meet the actual needs of people during the running process. People who experience sports are more likely to get injured. Using the embedded image system to conduct sustainable simulations of people running along the coast can fully analyze and investigate the injuries related to running, so that people can exercise more scientifically and promote running along the coast. At the same time, in order to improve the image display effect and algorithm efficiency of embedded image processing system in low resolution environment, Bresenham anti aliasing algorithm of region cloth is improved. The combination of linear scan conversion algorithm and region anti aliasing algorithm can effectively improve the drawing speed and operation efficiency of anti aliasing algorithm.

Fast 3-D Ultrasonic Imaging Using Time-Domain Synthetic Aperture Focusing Techniques Based on Circular Scan Conversions

Drawing-arc-based synthetic aperture focusing technique (DAB-SAFT) is capable of greatly improving the imaging speed by reinterpreting the focusing process in the forward direction, but it is only suitable for a two-dimensional (2-D) ultrasonic testing. By extending DAB-SAFT to fast 3-D ultrasonic imaging, this paper proposes both spherical scan-conversion-based SAFT and a spherical-surface-conversion-based SAFT (SSCB-SAFT) for a 3-D nondestructive testing. In SSCB-SAFT, the entire imaging procedure is converted to multiple scan-conversion operations of spherical surfaces. To obtain the coordinates of pixels on a given spherical surface, the spherical scan-conversion algorithm is presented based on circular scan conversions to speed up the imaging procedure by avoiding the time-consuming computations of root-mean-square distances. Besides, the performance of DAB-SAFT is further improved based on the relative positions between different scanning positions, which largely reduce the number of circular arc scan-conversion operations. This acceleration strategy is also applicable to SSCB-SAFT. The simulation experiments show that the improved SSCB-SAFT speeds up the imaging procedure four times while maintaining the same results.

A real-time data-based scan conversion method for single element ultrasound transducers

The current work investigates the performance of a real-time scan conversion algorithm for generating a 2-D ultrasound image from a laterally scanned single-element ultrasound transducer, which has applications in point-of-care devices such as for skin imaging. The algorithm employs a fixed calibration curve to update a predefined image grid in real time. Simulations showed that the calibration curve (with a maximum of 1) is robust to changes in scatterer concentration (8.3×10-3 mean absolute error), signal to noise ratio (1.0×10-3 mean absolute error for −5 dB SNR), and can be accurately predicted from a small number (31) of point scatterers (6.9×10-3 mean absolute error). Good agreement was also found between the calibration curves obtained from simulated and experimental data (1.19×10-2 mean absolute error). The scan conversion algorithm was validated by evaluation of the position estimation errors on both simulations and experiments. Clinical images of skin lesions (N = 20) demonstrate the feasibility of the algorithm for real, non-homogeneous tissue. Use of a fixed calibration curve compared to an adaptive calibration curve gave similar accuracies in the scanning step size range of 150–350 μm (with an average overlap of the accuracy ranges of 92.94% for simulations and 42.83% for experiments), and a 350-fold improvement in computation time.

A New Dynamic Programming Approach for Scan Conversion of a Circle

Generally curve may be generated as a sequence of many small lines; some curves like circle, parabola, ellipse, in particular can be generated with help of D.D.A. algorithm and other special algorithms. There are two main recursive algorithms for scan conversion of the circle on computer screen, the Bresenhams and the Midpoint circle generating algorithm both are pixel based; in this paper we are presenting a recursive new approach for scan conversion of the circle. The pixel in one octant has been determined with help of this algorithm and rest of the parts of the circle will be generated with help of symmetry. General Terms Dynamic Programming, Symmetry, Euclidean geometry, Octant

Performance of New GPU-Based Scan-Conversion Algorithm Implemented Using OpenGL

A new GPU-based scan-conversion algorithm implemented using OpenGL is described. The compute performance of this new algorithm running on a modem GPU is compared to the performance of three common scan-conversion algorithms (nearest-neighbor, linear interpolation and bilinear interpolation) implemented in software using a modem CPU. The quality of the images produced by the algorithm, as measured by signal-to-noise power, is also compared to the quality of the images produced using these three common scan-conversion algorithms.

Speed-up of the disaggregation of emission inventories and increased resolution of disaggregated maps using landuse data

This study describes the full disaggregation process of emission inventory maps in support of environmental modeling studies in a geographical information system. Using a heuristic approach, appropriate algorithms were found to accelerate the computational disaggregation speed. The algorithms were based on scan-conversion algorithms employed in the field of computer graphics. Various algorithms were analyzed in terms of supporting emission inventories with different shapes, such as points, polylines and polygons. The algorithms were implemented by using Visual Basic, thereby enabling the efficiencies of the algorithms to be analyzed and compared with each other. For the disaggregation of polygon types, with the aim of increasing the resolution of an inventory map, we suggest the advanced polygon-disaggregation method with land use data. An air dispersion simulation was performed in order to compare the accuracy of the emission input data generated by existing disaggregation methods and the advanced method proposed in the present study.

Real-Time 3-D Ultrasound Scan Conversion Using a Multicore Processor

Real-time 3-D ultrasound scan conversion (SC) in software has not been practical due to its high computation and I/O data handling requirements. In this paper, we describe software-based 3-D SC with high volume rates using a multicore processor, Cell. We have implemented both 3-D SC approaches: 1) the separable 3-D SC where two 2-D coordinate transformations in orthogonal planes are performed in sequence and 2) the direct 3-D SC where the coordinate transformation is directly handled in 3-D. One Cell processor can scan-convert a 192 x 192 x 192 16-bit volume at 87.8 volumes/s with the separable 3-D SC algorithm and 28 volumes/s with the direct 3-D SC algorithm.

2D point-in-polygon test by classifying edges into layers

The 2D point-in-polygon test is a fundamental problem in geometry, and of importance in various applications in computer graphics and other areas. In taking advantage of the basic idea of the polygon scan conversion algorithm, a novel method for the point-in-polygon test is proposed in this paper, capable of handling simple polygons in arbitrary shapes, possibly with holes. In the preprocess of the method, the edges of the polygon are classified into layers according to the occlusion relations between the edges viewed orthogonally in a direction, called the test direction, which guarantees that the edges of a layer can be occluded by only the edges of its preceding layers. At the same time, the edges at each layer are queued up respectively along the direction vertical to the test direction because there is no occlusion relation between the edges of the same layer. As a result, based on the layers, the calculation of the segments by the line through the tested point to intersect the polygon along the test direction, and then the inclusion test of the point against the segments could be feasibly made. The method has a low storage requirement in O( n), here, n is the number of the edges of the polygon. The time complexity of its preprocess ranges from O( n) to O( n 2), depending on the polygon shape and the test direction. And its inclusion test has a time complexity between O(log( n)) and O( n), but less than O((log( n)) 2) in most cases, depending on the construction of the layers. In the case of convex polygons and monotone polygons, the time complexity for the preprocess and the inclusion test could be O( n) and O(log( n)), respectively. On the other hand, the method is also easy to integrate with a variety of existing methods such as ray crossing methods and grid-based methods for improving the inclusion test further. Experimental results show that the method is robust and efficient in computation.

Accelerating techniques in volume rendering of irregular data

Volume rendering of irregular data has become a challenging research topic in the area of scientific visualization in recent years. In comparison with regular data rendering, irregular data volume rendering faces many new problems. Because cells in an irregular volume have various shape and size, volume rendering by the raycasting method has more difficulty in calculating the intersection between rays and cells, and the projection method has even greater trouble in queuing up cells, in particular concave cells. To accelerate volume rendering of irregular data, this paper presents a hybrid method which possesses the advantages of both raycasting and projection methods. The main strategy in the method is using a polygon scan conversion algorithm in 3-D space to set up a ray path with high efficiency, and by establishing intersection links to allow the operation of color composition to be locally conducted on-the-fly. As a result, it is possible to produce high quality images without the requirement of the heavy task for cell queuing up and complex ray intersection calculation.

A Real-Time Scan Conversion Algorithm on Commercially Available Microprocessors1

We have developed a new ultrasound scan conversion algorithm that can be executed very efficiently on modern microprocessors. Our algorithm is designed to handle the address calculations and input and output (I/O) data loading concurrently with the interpolation. The processing unit's computing power can be dedicated to performing pixel interpolations while the other operations are handled by an independent direct memory access (DMA) controller. By making intelligent use of the I/O transfer capabilities of the DMA controller, the algorithm avoids spending the processing unit's valuable computing cycles in address calculations and nonactive pixel blanking. Furthermore, the new approach speeds up the computation by utilizing the ability of superscalar and very long instruction word (VLIW) processors to perform multiple operations in parallel. Our scan conversion algorithm was implemented on a multimedia and imaging system based on the Texas Instruments TMS320C80 Multimedia Video Processor (MVP). Computing cycles are spent only on predeterminable nonzero output pixels. For example, an execution time of 11.4 ms was achieved when there are 101,829 nonzero output pixels. This algorithm demonstrates a substantial improvement over previous scan conversion algorithms, and its optimized implementation enables modern commercially available programmable processors to support scan conversion at video rates.

A real-time scan conversion algorithm on commercially available microprocessors.

We have developed a new ultrasound scan conversion algorithm that can be executed very efficiently on modern microprocessors. Our algorithm is designed to handle the address calculations and input and output (I/O) data loading concurrently with the interpolation. The processing unit's computing power can be dedicated to performing pixel interpolations while the other operations are handled by an independent direct memory access (DMA) controller. By making intelligent use of the I/O transfer capabilities of the DMA controller, the algorithm avoids spending the processing unit's valuable computing cycles in address calculations and nonactive pixel blanking. Furthermore, the new approach speeds up the computation by utilizing the ability of superscalar and very long instruction word (VLIW) processors to perform multiple operations in parallel. Our scan conversion algorithm was implemented on a multimedia and imaging system based on the Texas Instruments TMS320C80 Multimedia Video Processor (MVP). Computing cycles are spent only on predeterminable nonzero output pixels. For example, an execution time of 11.4 ms was achieved when there are 101,829 nonzero output pixels. This algorithm demonstrates a substantial improvement over previous scan conversion algorithms, and its optimized implementation enables modern commercially available programmable processors to support scan conversion at video rates.

Hybrid scan-conversion of circles

Conventional algorithms for scan-conversion of circles select one pixel in each iteration. Run-length slice circle algorithms have therefore been suggested. These algorithms determine a run of pixels in each iteration. The speed of scan-conversion is therefore increased due to I/O. A hybrid approach to the scan-conversion of circles is presented. The new approach combines the advantages of the two methods into a hybrid algorithm. Speedup is achieved in the hybrid algorithm not only due to the reduction in the number of I/O operations, but also due to a reduction in the number of arithmetic operations.

REGION COLORING, EDGE COLORING, AND SCAN-CONVERSION OF MAPS

A theory is introduced relating extrinsic colorings of complementary regions of an embedded graph to certain intrinsic colorings of the edges of the graph, called color cycles, that satisfy a certain self-consistency condition. A region coloring is lifted to an edge coloring satisfying the cycle condition, and a dual construction builds a region coloring from any color cycle and any embedding of the graph. Both constructs are canonical, and the constructions are information-conservative in the sense that lifting an arbitrary region coloring to a color cycle and then reconstructing a region coloring from the cycle, using the same embedding, results in the original region coloring. The theory is motivated by, and provides the proof of correctness of, new scan-conversion algorithms that are useful in settings where region boundaries have very high complexity. These algorithms have been implemented and provide useful display functionality previously unavailable on certain rastor devices.

Parallel algorithms for circle detection in images

The detection of circles in images is an important task in many computer vision applications. When the three parameters (center coordinates and radius) of a circle are quantized into O( n) values each, a sequential algorithm using the Hough transform runs with a time complexity of O( n 4), where n × n is the size of the image. When information about the gradient direction is also used, the complexity of the sequential algorithm reduces to O( n 3). This paper proposes three parallel algorithms for circle detection on an n × n mesh of processing elements operating in the SIMD mode. The first two algorithms use the Hough transform and the third is based on a tracing algorithm. The first algorithm uses only the gradient magnitude and takes O( n 3) time. The second uses both the gradient magnitude and gradient direction and runs in O( n 2) time. The third method uses a midpoint circle scan conversion algorithm and runs with a complexity of O( n 2). This algorithm is the most efficient of the three. It does not use the gradient direction and offers an improvement of O( n 2) over its sequential counterpart that runs in O( n 4) time. When implemented with a table look-up operation, this algorithm has a low proportionality constant and offers a significant improvement in computational speed.

Flow visualization with surface particles

A technique for rendering particles in general, and surface particles in particular, is presented. This technique incorporates an improved shading model, the use of Gaussian filters to prevent spatial and temporal artifacts, and an efficient scan-conversion algorithm. The steps of the rendering are described: shading, filtering, scan conversion, and occlusion. Ways in which the process may be varied to further improve the results and widen the range of applications are discussed. >

Discrete ray tracing

Discrete ray tracing, or 3-D raster ray tracing (RRT), which, unlike existing ray tracing methods that use geometric representation for the 3-D scene employs a 3-D discrete raster of voxels for representing the 3-D scene in the same way a 2-D raster of pixels represents a 2-D image, is discussed. Each voxel is a small quantum unit of volume that has numeric values associated with it representing some measurable properties or attributes of the real object or phenomenon at that voxel. It is shown that RRT operates in two phases: preprocessing voxel and discrete ray tracing. In the voxel phase, the geometric model is digitized using 3-D scan-conversion algorithms that convert the continuous representation of the model into a discrete representation within the 3-D raster. In the second phase, RRT employs a discrete variation of the conventional recursive ray tracer in which 3-D discrete rays are traversed through the 3-D raster to find the first surface voxel. Encountering a nontransparent voxel indicates a ray-surface hit. Results obtained by running the RRT software one one 20-MIPS (25-GHz) processor of a Silicon Graphics 4D/240GTX are presented in terms of CPU time.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A scan conversion algorithm using quad‐tree representation of dZ buffer

AbstractThis paper proposes an extension of the Z buffer or dZ buffer that stores not only the Z component but also the normal vector of a visible polygon at the sampling point. While the conventional Z buffer algorithm is based on a zeroth‐order approximation of a visible polygon, the dZ buffer is considered as a first‐order approximation. As a result, the dZ buffer can approximate a surface by fewer sampling points.A quad‐tree based internal representation of the dZ buffer and scan conversion algorithm has been proposed using the representation. The proposed algorithm uses memory in proportion to the complexity of the generated image while the Z buffer uses memory in proportion to the image size. While the algorithm allows an incremental update of the dZ buffer as similarly to the Z buffer, anti‐alias processing is possible by controlling oversampling on demand.The algorithm can be implemented using recursive procedure calls including simple overlapping detection of triangles and rectangles. The algorithm is implemented and evaluated on a UNIX workstation and the result shows better figures in both conversion time and memory requirement.

High speed high quality antialiased vector generation

A vector generation method is described in which a high quality image rendering scheme is coupled with a high speed scan-conversion algorithm.The rendering scheme consists of two parts. First a prefiltering method is used to antialias the vectors. Second a compositing technique is used to compose the vectors into the frame-buffer.The scan-conversion algorithm presented allows a single vector to be scan-converted by a either by a single processor or a set of processors running in parallel. When using parallel processors, antialiased vectors may be scan-converted and written to a frame store at the same high speed as aliased vectors. The VLSI technology used to implement this algorithm is capable of drawing over two million high quality antialiased vectors per second.

On parallel scan-conversion algorithms for transputer networks

Two fundamental scan line procedures are considered from the point of view of parallel implementation on transputer networks. The paper describes algorithms for the scan conversion of polygons, and the related hidden surface elimination problem for three-dimensional models with polygonal data structures. In each case parallel designs have been implemented and timed in various configurations against a functionally equivalent, but not necessarily optimized, single processor code. The results presented demonstrate that scan line algorithms can be efficiently implemented on suitably configured networks of transputers.