Abstract

We present a novel hybrid scheme called "hyper-resolution" that integrates image probability-filtering-based interpolation and improved Poisson maximum a posteriori (MAP) super-resolution to respectively enhance high spatial and spatial-frequency resolutions of a single down-sampled image. A new approach to interpolation is proposed for simultaneous image interpolation and smoothing by exploiting the probability filter coupled with a pyramidal decomposition and the Poisson MAP super-resolution is improved with the techniques of edge maps and pseudo-blurring. Simulation results demonstrate that this hyper-resolution scheme substantially improves the quality of a single gray-level, color, or noisy image, respectively.

Highlights

  • The quality of an image can be evaluated on its spatial and spatial-frequency resolutions

  • With the comparison between B-spline and probability-filtering-based interpolation, it can be found that bilinear or cubic spline interpolation performs on an image as weighted mean filtering while the probability-filteringbased interpolation acts as an adaptive filtering useful for preserving image features in addition to image interpolation; that is because the former creates interpolated pixels by averaging their own neighborhood pixels and the latter analyzes the characteristics of surrounding pixels prior to interpolating pixels

  • The interpolation was done with a factor of 22 for each cycle; the super-resolution procedure of the proposed hyper-resolution scheme, shown in Figure 3, adopted 25 iterations and the point spread function (PSF) with a standard deviation of 1 pixel because of the pyramidal decomposition used here, four neighboring pixels in the interpolated image mainly contributing to one pixel in its own decimated image

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Summary

INTRODUCTION

The quality of an image can be evaluated on its spatial and spatial-frequency resolutions. Image interpolation is performed by pixel replication in a small neighborhood of each existing pixel This is equivalent to a first-order linear filter. The improved Poisson maximum a posteriori (MAP) super-resolution [23] is performed to reconstruct the high spatial-frequency spectrum of the interpolated image. To illustrate the performance of the proposed scheme, this research has studied the resolution enhancement on gray-level, color, and noisy images, respectively, and comparisons will be made among the superresolution coupled with different interpolators.

B-SPLINE INTERPOLATION
NOVEL HYPER-RESOLUTION SCHEME
Interpolation based on the probability filter
Improved Poisson MAP super-resolution algorithm
Analysis of the hyper-resolution scheme
EXPERIMENTAL RESULTS AND EVALUATIONS
Resolution enhancement of gray-level images
Resolution enhancement of color images
Resolution enhancement of noisy images
CONCLUSIONS
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