Image Interpolation Using Fourier Phase Features

Image interpolation has been widely used for enhancing spatial resolution of the input images. Generally, the spatial resolution enhancement techniques are categorized into single frame and multiple frame super resolution. Multi-frame super resolution techniques use a set of low resolution frames, while single image super resolution only requires one single input to reconstruct a high resolution image. In real life applications, single image super resolution is preferred when lacking of multiple frames in the data. In this work, we present a single image interpolation approach for reproducing high frequency missing components of the input low resolution images. The high frequency feature is first extracted in Fourier domain, and then the system is trained to regenerate better pixel values, which contribute to better resolution. We evaluate the method visually and quantitatively using several test images.https://ecommons.udayton.edu/stander_posters/1822/thumbnail.jp

Single image example-based super-resolution using cross-scale patch matching and Markov random field modelling

Example-based super-resolution has become increasingly popular over the last few years for its ability to overcome the limitations of classical multi-frame approach. In this paper we present a new example-based method that uses the input low-resolution image itself as a search space for high-resolution patches by exploiting self-similarity across different resolution scales. Found examples are combined in a high-resolution image by the means of Markov Random Field modelling that forces their global agreement. Additionally, we apply back-projection and steering kernel regression as post-processing techniques. In this way, we are able to produce sharp and artefact-free results that are comparable or better than standard interpolation and state-of-the-art super-resolution techniques

Confidence-aware Levenberg-Marquardt optimization for joint motion estimation and super-resolution

Motion estimation across low-resolution frames and the reconstruction of high-resolution images are two coupled subproblems of multi-frame super-resolution. This paper introduces a new joint optimization approach for motion estimation and image reconstruction to address this interdependence. Our method is formulated via non-linear least squares optimization and combines two principles of robust super-resolution. First, to enhance the robustness of the joint estimation, we propose a confidence-aware energy minimization framework augmented with sparse regularization. Second, we develop a tailor-made Levenberg-Marquardt iteration scheme to jointly estimate motion parameters and the high-resolution image along with the corresponding model confidence parameters. Our experiments on simulated and real images confirm that the proposed approach outperforms decoupled motion estimation and image reconstruction as well as related state-of-the-art joint estimation algorithms.Comment: accepted for ICIP 201

Multi-frame Image Super-resolution Reconstruction Using Multi-grained Cascade Forest

Super-resolution image reconstruction utilizes two algorithms, where one is for single-frame image reconstruction, and the other is for multi-frame image reconstruction. Single-frame image reconstruction generally takes the first degradation and is followed by reconstruction, which essentially creates a problem of insufficient characterization. Multi-frame images provide additional information for image reconstruction relative to single frame images due to the slight differences between sequential frames. However, the existing super-resolution algorithm for multi-frame images do not take advantage of this key factor, either because of loose structure and complexity, or because the individual frames are restored poorly. This paper proposes a new SR reconstruction algorithm for images using Multi-grained Cascade Forest. Multi-frame image reconstruction is processed sequentially. Firstly, the image registration algorithm uses a convolutional neural network to register low-resolution image sequences, and then the images are reconstructed after registration by the Multi-grained Cascade Forest reconstruction algorithm. Finally, the reconstructed images are fused. The optimal algorithm is selected for each step  to get the most out of the details and tightly connect the internal logic of each sequential step.This novel approach proposed in this paper, in which the depth of the cascade forest is procedurally generated for recovered images, rather than being a constant. After training each layer, the recovered image is automatically evaluated, and new layers are constructed for training until an optimal restored image is obtained. Experiments show that this method improves the quality of image reconstruction while preserving the details of the image

Multi-frame Image Super-resolution Reconstruction Using Multi-grained Cascade Forest

Super-resolution image reconstruction utilizes two algorithms, where one is for single-frame image reconstruction, and the other is for multi-frame image reconstruction. Single-frame image reconstruction generally takes the first degradation and is followed by reconstruction, which essentially creates a problem of insufficient characterization. Multi-frame images provide additional information for image reconstruction relative to single frame images due to the slight differences between sequential frames. However, the existing super-resolution algorithm for multi-frame images do not take advantage of this key factor, either because of loose structure and complexity, or because the individual frames are restored poorly. This paper proposes a new SR reconstruction algorithm for images using Multi-grained Cascade Forest. Multi-frame image reconstruction is processed sequentially. Firstly, the image registration algorithm uses a convolutional neural network to register low-resolution image sequences, and then the images are reconstructed after registration by the Multi-grained Cascade Forest reconstruction algorithm. Finally, the reconstructed images are fused. The optimal algorithm is selected for each step  to get the most out of the details and tightly connect the internal logic of each sequential step.This novel approach proposed in this paper, in which the depth of the cascade forest is procedurally generated for recovered images, rather than being a constant. After training each layer, the recovered image is automatically evaluated, and new layers are constructed for training until an optimal restored image is obtained. Experiments show that this method improves the quality of image reconstruction while preserving the details of the image

A Super-resolution Reconstruction Method of Remotely Sensed Image Based on Sparse Representation

The traditional method of image super-resolution reconstruction uses the sub-pixel displacement information between multi-frame low-resolution images to reconstruct a high-resolution image. Image super-resolution reconstruction is a typical mathematical inverse problem, and it is ill-posed problem [1]. To solve this problem, prior knowledge of data or question should be added. As the latest development achievements of signal priori or modeling, sparse representation of the signal has been studied in depth in the field of image processing. Super-resolution reconstruction based on sparse representation can improve the image quality and get richer image details [8]. Due to the sparse representation of image reconstruction has strong priority, this paper focuses on super-resolution reconstruction of the single frame remotely sensed image based on sparse representation. Compared with other algorithms, it is proved that the super-resolution reconstruction algorithm based on sparse representation has advantages in remotely sensed image reconstruction

A Collaborative Adaptive Wiener Filter for Multi-frame Super-resolution

Factors that can limit the effective resolution of an imaging system may include aliasing from under-sampling, blur from the optics and external factors, and sensor noise. Image restoration and super-resolution (SR) techniques can be used to improve image resolution. One SR method, developed recently, is the adaptive Wiener filter (AWF) SR algorithm. This is a multi-frame SR method that combines registered temporal frames through a joint nonuniform interpolation and restoration process to provide a high-resolution image estimate. Variations of this method have been demonstrated to be effective for multi-frame SR, as well demosaicing RGB and polarimetric imagery. While the AWF SR method effectively exploits subpixel shifts between temporal frames, it does not exploit self similarity within the observed imagery. However, very recently, the current authors have developed a multi-patch extension of the AWF method. This new method is referred to as a collaborative AWF (CAWF). The CAWF method employs a finite size moving window. At each position, we identify the most similar patches in the image within a given search window about the reference patch. A single-stage weighted sum of all of the pixels in all of the similar patches is used to estimate the center pixel in the reference patch. Like the AWF, the CAWF can perform nonuniform interpolation, deblurring, and denoising jointly. The big advantage of the CAWF, vs. the AWF, is the CAWF can also exploit self-similarity. This is particularly beneficial for treating low signal-to-noise ratio (SNR) imagery. To date, the CAWF has only been developed for Nyquist-sampled single-frame image restoration. In this paper, we extend the CAWF method for multi-frame SR. We provide a quantitative performance comparison between the CAWF SR and the AWF SR techniques using real and simulated data. We demonstrate that CAWF SR outperforms AWF SR, especially in low SNR applications

Enhancing Multi-View 3D-Reconstruction Using Multi-Frame Super Resolution

Multi-view stereo is a popular method for 3D-reconstruction. Super resolution is a technique used to produce high resolution output from low resolution input. Since the quality of 3D-reconstruction is directly dependent on the input, a simple path is to improve the resolution of the input. In this dissertation, we explore the idea of using super resolution to improve 3D-reconstruction at the input stage of the multi-view stereo framework. In particular, we show that multi-view stereo when combined with multi-frame super resolution produces a more accurate 3D-reconstruction. The proposed method utilizes images with sub-pixel camera movements to produce high resolution output. This enhanced output is fed through the multi-view stereo pipeline to produce an improved 3D-model. As a performance test, the improved 3D-model is compared to similarly generated 3D-reconstructions using bicubic and single image super resolution at the input stage of the multi-view stereo framework. This is done by comparing the point clouds of the generated models to a reference model using the metrics: average, median, and max distance. The model that has the metrics that are closest to the reference model is considered to be the better model. The overall experimental results show that the generated models, using our technique, have point clouds with average mean, median, and max distances of 4.3\%, 8.8\%, and 6\% closer to the reference model, respectively. This indicates an improvement in 3D-reconstruction using our technique. In addition, our technique has a significant speed advantage over the single image super resolution analogs being at least 6.8x faster. The use of multi-frame super resolution in conjunction with the multi-view stereo framework is a practical solution for enhancing the quality of 3D-reconstruction and shows promising results over single image up-sampling techniques