Subpixel rendering

About: Subpixel rendering is a research topic. Over the lifetime, 3885 publications have been published within this topic receiving 82789 citations.

Method for generating a subpixel mask for computer graphics system and apparatus thereof

Abstract: In a computer graphics system, a method for generating a subpixel mask for polygon edges directly by an operation without using a look-up table, includes the steps of forming subblocks by dividing a pixel into n subpixels depending on the slope of the polygon edge, calculating subblock coverage which is a distance from the pixel boundary to the intersection point of n subblocks and polygon edge, and generating an n×n subpixel mask depending on the calculated subblock coverage. In an apparatus using the method, edge-generated aliasing is removed.

Modification of pixel-swapping algorithm with initialization from a sub-pixel/pixel spatial attraction model

Abstract: Pixel-swapping algorithm is a simple and efficient technique for sub-pixel mapping (Atkinson, 2001 and 2005). It was initially applied in shoreline and rural land-cover mapping but has been expanded to other land-cover mapping. However, due to its random initializing process, this algorithm must swap a large number of sub-pixels, and therefore it is computation intensive. This computing power consumption intensifies when the scale factor is large. A new, modified pixel-swapping algorithm (MPS) is presented in this paper to reduce the computation time, as well as to improve sub-pixel mapping accuracy. The MPS algorithm replaces the original random initializing process with a process based on a sub-pixel/pixel spatial attraction model. The new algorithm was used to allocate multiple land-covers at the subpixel level. The results showed that the MPS algorithm outperformed the original algorithm both in sub-pixel mapping accuracy and computational time. The improvement is especially significant in the case of large scale factors. Furthermore, the MPS is less sensitive to the size of neighboring sub-pixels and can still result in increased accuracy even if the size of neighbors is small. The MPS was also much less time consuming, as it reduced both the iterations and total amount of swapping needed.

Hardware based interdigitation

Abstract: A system and method for interdigitating multiple perspective views in a stereoscopic image viewing system. A lenticular sheet is affixed in intimate juxtaposition with a display area having a defined aspect ratio. The display area includes a plurality of scan lines each having a plurality of pixels, each pixel including subpixels. A map having the same resolution as the display is created to store values corresponding to each subpixel in the display area. Preferably, the map is generated beforehand and stored for later use through a lookup operation. A buffer stores a frame having n views, wherein each of the n views has the same aspect ratio as the display area. A plurality of masks is also created and stored. Each mask corresponds to a unique one of the n views and includes opaque areas and a plurality of transparent windows, each of which corresponds to a selected subpixel location. The n views are then interdigitated while applying the corresponding masks, and a value is assigned to each subpixel using the map.

Correction method and software for image distortion and nonuniform response in charge-coupled device-based X-ray detectors utilizing X-ray image intensifier

Abstract: An on-site method of correcting the image distortion and nonuniform response of a charge-coupled device (CCD)-based X-ray detector was developed using the response of the imaging plate as a reference. The CCD-based X-ray detector consists of a beryllium-windowed X-ray image intensifier (Be-XRII) and a CCD as the image sensor. An image distortion of 29% was improved to less than 1% after the correction. In the correction of nonuniform response due to image distortion, subpixel approximation was performed for the redistribution of pixel values. The optimal number of subpixels was also discussed. In an experiment with polystyrene (PS) latex, it was verified that the correction of both image distortion and nonuniform response worked properly. The correction for the "contrast reduction" problem was also demonstrated for an isotropic X-ray scattering pattern from the PS latex.

How Accurate Can Block Matches Be in Stereo Vision

Abstract: This article explores the subpixel accuracy attainable for the disparity computed from a rectified stereo pair of images with small baseline. In this framework we consider translations as the local deformation model between patches in the images. A mathematical study first shows how discrete block-matching can be performed with arbitrary precision under Shannon-Whittaker conditions. This study leads to the specification of a block-matching algorithm which is able to refine disparities with subpixel accuracy. Moreover, a formula for the variance of the disparity error caused by the noise is introduced and proved. Several simulated and real experiments show a decent agreement between this theoretical error variance and the observed root mean squared error in stereo pairs with good signal-to-noise ratio and low baseline. A practical consequence is that under realistic sampling and noise conditions in optical imaging, the disparity map in stereo-rectified images can be computed for the majority of pixels (but only for those pixels with meaningful matches) with a $1/20$ pixel precision.