Showing papers on "Image scaling published in 1991"

Directional interpolation of images based on visual properties and rank order filtering

Abstract: The goal of this research is to develop interpolation techniques which preserve or enhance the local structure critical to image quality. Preliminary results are presented which exploit either the properties of vision or the properties of the image in order to achieve the goals. Directional image interpolation is considered which is based on a local analysis of the spatial image structure. The extension of techniques for the design of linear filters based on properties of human perception reported previously to enhance the perceived quality of interpolated images is considered. >

Motion/pattern adaptive interpolation of interlaced video sequences

Abstract: A hybrid motion/pattern adaptive scheme for the conversion of interlaced video sequences to the progressive format is presented. It normally operates in the temporal interpolation model and switches to spatial interpolation when motion is detected. The filter for spatial interpolation is adapted according to the local image pattern. Directional filters are designed for oriented features based on their representation by oriented polynomials. Although the proposed scheme has only been applied to the interpolation of interlaced signals, its principle is applicable to other problems in video signal resolution enhancement. >

Basic principles of stereographic software development

Abstract: Generation of images for a time-multiplexed stereoscopic display environment is not a straightforward extension of image generation in a perspective graphics environment. There are several factors that must be taken into account in order to produce high-quality, stereographic images. An overview is provided of some of the factors that are important to the proper construction and display of computer graphic images in a time-multiplexed environment. In particular, image generation algorithms, horizontal parallax, interocular cross talk and ghosting, refresh rate, image scaling, and interaction with 3-D spaces are discussed.

Image resampling in remote sensing and image visualization applications

Abstract: Imaging applications often require image warping in order to obtain a desired spatial effect. In implementing a warping technique, means for transforming and resampling the source data must be chosen. A forward or reverse transformation mapping can be selected, though interpolation is more accurate using the reverse format. When applying a noninvertible transformation, forward mapping becomes necessary. A technique called bin mapping introduces an intermediate storage mechanism which allows for precise interpolation while applying a forward transformation.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Directional 3-D interpolation technique for volume rendering

Abstract: A 3-D interpolation method is proposed as the preprocessing step for 3-D visualization to compensate the poor interslice resolution in 3-D medical imaging The proposed method uses the surface information which is obtained at each voxel using local gradients If the voxel to be interpolated is found on a surface or in its vicinity, interpolation is performed along the direction parallel to the surface; otherwise interpolation is done along the vertical z-direction Since the method uses correlation information inherent in 3-D data effectively, it can provide the interpolated image which preserves the surface smoothness and also reduces the interpolation error near the surface As experimental results, volume rendering and cut-view images of interpolated 3-D medical data are presented >

Fast anamorphic image scaling

Abstract: Publisher Summary This chapter discusses a fast anamorphic image scaling method. There are many ways to rescale an image to the desired size. Some are considerably more accurate than others, and the more accurate methods generally are more computationally intensive. Pixel remapping operations like stretching, rotation, skewing, and rescaling are often implemented, as mappings from positions in the source image to positions in the destination image. This approach, however, often leaves “holes” in the destination because of rounding error in the computation of the destination position or the fact that there is not a one-to-one mapping between source pixels and destination pixels. Taking a different approach to the problem can eliminate these errors. Now one thinks of the remapping as defining which source pixel a particular destination pixel is taken from. This maps positions in the destination from positions in the source. The processing loop then is over the destination pixels rather than the source pixels, and thus, each pixel in the destination is assigned a value, even if more than one destination pixel maps from the same source pixel. This method chooses only one source pixel, always the most correct for a given mapping.

Method and device for binarizing gradation image

Abstract: PURPOSE:To obtain a clear binary image by using a half-contrast binarizing method to such a subject where a desired picture element to be extracted has a certain level of density with other picture elements kept approximately at density '0' respectively CONSTITUTION:A gradation image binarizing device consists of a TV camera 10, an A/D converter 11, an image memory 12, a differentiation circuit 13, an image scaling circuit 14, a local maximum value filter circuit 15, a smoothing circuit 16, an intra-image arithmetic circuit 17, a binarizing circuit 18, a CPU 19, a D/A converter 20, and a monitor 21 Then a threshold value image is produced from an image having its luminance set at 1/n (n: an integer of >=2 usually set at 2) against an image where a desired area to be extracted has a certain level of density with other areas kept approximately at density '0' respectively As a result, a clear binary image is obtained

Reconstruction of quincunx-coded image sequences using vector median

Abstract: A novel method for reconstruction of offset field quincunx coded color image sequences by processing signal components as vectors is presented. A multidimensional weighted vector median interpolation filter is introduced. The suggested interpolation method provides perfect reconstruction of still image areas and has good properties in moving areas of the sequence without any motion information. The performance of the proposed methods is tested using a video sequencer.

Interpolation algorithm for unequally spaced image data with image quality correction capability

Abstract: An image interpolation algorithm considering the sensor aperture characteristics of unequally spaced image data is presented. Recently, it has become possible to gather images by a high spatial resolution sensor on a satellite. Precision image processing is required to correct images which have blurs and geometric distortions due to the sensor characteristics. To realize precision image processing, we propose an unequally spaced interpolation filter with image quality correction capability. It consists in a restoration filter, and equally and unequally spaced interpolation filters. Image quality improves by about 15 percent in unequally spaced regions, and interpolation accuracy of less than 0.5 in gray levels is obtained. This is shown by evaluation experiments using thematic mapper sensor-type simulation data.