In the field of image superresolution reconstruction (SRR), the prior can be employed to solve the ill-posed problem. However, the prior model is selected empirically and characterizes the entire image so that the local feature of image cannot be represented accurately. This paper proposes a feature-driven prior model relying on feature of the image and introduces a block-based maximum a posteriori (MAP) framework under which the image is split into several blocks to perform SRR. Therefore, the local feature of image can be characterized more accurately, which results in a better SRR. In process of recombining superresolution blocks, we still design a border-expansion strategy to remove a byproduct, namely, cross artifacts. Experimental results show that the proposed method is effective.
Current mainstream super-resolution algorithms based on deep learning use a deep convolution neural network (CNN) framework to realize end-to-end learning from low-resolution (LR) image to high-resolution (HR) images, and have achieved good image restoration effects. However, as the number of layers in the network is increased, better results are not necessarily obtained, and there will be problems such as slow training convergence, mismatched sample blocks, and unstable image restoration results. We propose a preclassified deep-learning algorithm (MGEP-SRCNN) using Multilabel Gene Expression Programming (MGEP), which screens out a sample sub-bank with high relevance to the target image before image block extraction, preclassifies samples in a multilabel framework, and then performs nonlinear mapping and image reconstruction. The algorithm is verified through standard images, and better objective image quality is obtained. The restoration effect under different magnification conditions is also better.The gradient descent method continuously adjusts the weights to obtain a mapping from LR to HR. Its simple network structure design and excellent image restoration results created a precedent for deep learning in super-resolution image reconstruction. However, the SRCNN method does not obtain better results when the number of layers in the network is increased. The training convergence rate is slow and it is not suitable for multiscale amplification.Based on the above problems, we propose an improved deep learning algorithm for Gene Expression Programming (GEP) preclassification. This method uses the GEP multilabeling algorithm to classify the trained image set and select a subset of samples that are related in color and texture feature categories, thereby reducing the complexity of the convolutional neural network parameters. We compare the performance of our approach to that of other state-of-the-art methods and obtain improved objective image quality.
Related WorkIn recent years, deep learning and artificial intelligence have been widely used in various industries, especially in the field of computer vision, and have achieved better results than traditional methods [14,15]. Using the feed-forward depth network methods of CNN is the mainstream of the current super-resolution reconstruction field after sparse representation. Such methods focus less on the reconstruction speed and more on whether the high-resolution map can be better restored at a large magnification. They have better generalization ability and ability to characterize the high-level characteristics, compared with traditional shallow learning algorithms.
SRCNN/Fast SRCNN (FSRCNN)Dong et al. [5] first proposed the use of a convolutional neural network for image super-resolution reconstruction. An LR image was first enlarged to the target size using Bicubic interpolation, and then a nonlinear mapping was performed through a three-layer convolutional network. The obtained results were output as high-resolution images, and good results were obtained. As s...
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