An Improved Medical Image Fusion Method Based on PCNN in NSST Domain

In order to more accurately realize fusion of remote sensing images, we propose a novel remote sensing images fusion algorithm combining extended non-subsampled shearlet transform (NSST) and modified pulse-coupled neural network (PCNN). Firstly, it makes histogram matching and intensity smoothing and filtering treatment on intensity component and full-color image of multi-spectral image. Secondly, such intensity component and full-color image are decomposed by extended NSST to get corresponding high-frequency and low-frequency coefficients. For low-frequency coefficients, fusion is made by sparse representation; for high-frequency coefficients, a modified pulse-coupled neural network (PCNN) strategy is put forward to process. Finally, the processed result is drawn by inverse transformation of the extended NSST and intensity-hue-saturation inverse transformation. The experimental results show that the proposed algorithm reserves as much spectral information as possible and improve spatial resolution; its visual effects and objective indexes are better than other classical fusion algorithms.

As a novel MGA (Multiscale Geometric Analysis) tool, shearlet is equipped with a rich mathematical structure similar to wavelet. In this paper, a novel image fusion method using Non-subsampled Shearlet Transform is proposed. First, the source images are decomposed into low-pass and high-pass subbands using NSST. Second, the high-pass subbands coefficients of the images are fused according to the average gradient. Third, the low-pass subbands coefficients of the images are fused by the weighted regional entropy. Finally, the image is reconstructed by the inverse non-subsampled shearlet transform. In the method, two sets of source images and five objective parameters are used to test the algorithm. The experimental results show that the proposed method is better than the conventional DWT-based and NSCT-based methods.

There are many artificial parameters when fuse infrared and visible images, to overcome the lack of detail in the fusion image because of the artifacts, a novel fusion algorithm for infrared and visible images that is based on different constraints in non-subsampled shearlet transform (NSST) domain is proposed. There are high bands and low bands of images that are decomposed by the NSST. After analyzing the characters of the bands, fusing the high level bands by the gradient constraint, the fused image can obtain more details; fusing the low bands by the constraint of saliency in the images, the targets are more salient. Before the inverse NSST, the Nash equilibrium is used to update the coefficient. The fused images and the quantitative results demonstrate that our method is more effective in reserving details and highlighting the targets when compared with other state-of-the-art methods.

Combined with the shared similarity among multiple source images and depth of field in a camera, a new image fusion algorithm based on nonsubsampled shearlet transform (NSST) domain is proposed. First, NSST is utilized for decomposition of the source images, the low frequency coefficients is fused by weight votes in the structure-driven regions by using shared similarity and depth of field (SSSID), and then apply larger sum-modified-Laplacian (SML) with depth of field to the high frequency coefficients, finally the fusion image is gained after we do the inverse NSST to the fused coefficients. The algorithm can not only preserve the information of the source images well, but also suppress pixel distortion due to nonlinear operations in transform domain. Experimental results demonstrate that the proposed method outperforms the state-of-the-art transform domain fusion methods on image quality and objective fusion criteria.

Presented is a novel technique to fuse multi‐sensor images using non‐subsampled shearlet transform (NSST) domain I 2 CM. First, multi‐scale and multi‐directional decompositions of source images can be performed by NSST. The classic ICM is improved to be I 2 CM which is then exploited to capture and extract the characteristics of each of the sub‐band images. Finally, the fused image is reconstructed from the fused sub‐images by adopting the inverse NSST. Experimental results demonstrate that the proposed image fusion scheme is very competitive compared with other conventional ones in both visual effect and objective evaluation criteria.

To overcome the artifact phenomenon caused by the incomplete registration of the source images, a new multi-focus image fusion approach is proposed based on sparse representation and non-subsampled shearlet transform (NSST). Firstly, the source images are decomposed to low- and high-frequency coefficients by NSST. The sparse representation is then adopted to fuse the low-frequency coefficients. For the high-frequency coefficients, a maximum sum-modified-Laplacian (SML) rule is put forward to merge them. Finally, the resultant image is obtained by the inverse NSST on the fused coefficients. Experimental results indicate that the proposed method can achieve satisfied effect compared with various existing image fusion methods.

In multi-scale geometric analysis (MGA)-based fusion methods for infrared and visible images, adopting the same representation for the two types of images will result in the non-obvious thermal radiation target in the fused image, which can hardly be distinguished from the background. To solve the problem, a novel fusion algorithm based on nonlinear enhancement and non-subsampled shearlet transform (NSST) decomposition is proposed. Firstly, NSST is used to decompose the two source images into low- and high-frequency sub-bands. Then, the wavelet transform (WT) is used to decompose high-frequency sub-bands to obtain approximate sub-bands and directional detail sub-bands. The “average” fusion rule is performed for fusion for approximate sub-bands. And the “max-absolute” fusion rule is performed for fusion for directional detail sub-bands. The inverse WT is used to reconstruct the high-frequency sub-bands. To highlight the thermal radiation target, we construct a non-linear transform function to determine the fusion weight of low-frequency sub-bands, and whose parameters can be further adjusted to meet different fusion requirements. Finally, the inverse NSST is used to reconstruct the fused image. The experimental results show that the proposed method can simultaneously enhance the thermal target in infrared images and preserve the texture details in visible images, and which is competitive with or even superior to the state-of-the-art fusion methods in terms of both visual and quantitative evaluations.

Thick cloud coverage presents a significant challenge for the analysis and application of multi-temporal remote sensing imagery. Although existing cloud removal methods attempt to exploit spatio-spectral-temporal correlations, they often fail to adequately capture cross-scale complementary features due to single-scale reconstruction limitations, resulting in texture degradation and color distortion effects. To address this issue, we propose a multi-scale fully connected tensor network decomposition method guided by the non-subsampled shearlet transform (NSST). The proposed approach first applies NSST in the spatial domain, followed by parameter-adaptive pulse-coupled neural network (PCNN) fusion of each decomposed subband along the temporal dimension to construct a high-quality guidance image. This guidance image is subsequently employed to impose regularization constraints on both high- and low-frequency components of the tensor network decomposition in the NSST domain, enabling a comprehensive representation of multi-scale correlations. To efficiently solve the resulting optimization model, we develop a proximal alternating minimization (PAM)-based algorithm. Extensive experiments on both simulated and real satellite datasets demonstrate that the proposed method consistently outperforms existing approaches, achieving average improvements of 1.2–3.5 dB in PSNR and 0.5–2.0% in SSIM over the best baseline across various cloud coverage scenarios, while maintaining superior detail preservation and color consistency.

ABSTRACTIn order to improve the accuracy of change detection and reduce the running time, a change detection method based on equal weight image fusion and adaptive threshold in the NSST domain is proposed. First, the logarithmic transformation is used to transform images and the mean filter is applied to the transformed images. The log-ratio method and the mean ratio method are adopted to generate two kinds of difference images. The final difference image is achieved by equal weight image fusion method. Then, an adaptive threshold denoising method based on non-subsampled shearlet transform (NSST) is used to achieve noise reduction. Finally, the k-means clustering algorithm is utilized to get the change detection results. The experimental results show that the proposed algorithm has better change detection performance than the reference algorithms in visual effect and objective parameters.

In the current era of technological development, medical imaging plays an important role in many applications of medical diagnosis and therapy. In this regard, medical image fusion could be a powerful tool to combine multi-modal images by using image processing techniques. But, conventional approaches failed to provide the effective image quality assessments and robustness of fused image. To overcome these drawbacks, in this work three-stage multiscale decomposition (TSMSD) using pulse-coupled neural networks with adaptive arguments (PCNN-AA) approach is proposed for multi-modal medical image fusion. Initially, nonsubsampled shearlet transform (NSST) is applied onto the source images to decompose them into low frequency and high frequency bands. Then, low frequency bands of both the source images are fused using nonlinear anisotropic filtering with discrete Karhunen–Loeve transform (NLAF-DKLT) methodology. Next, high frequency bands obtained from NSST are fused using PCNN-AA approach. Now, fused low frequency and high frequency bands are reconstructed using NSST reconstruction. Finally, band fusion rule algorithm with pyramid reconstruction is applied to get final fused medical image. Extensive simulation outcome discloses the superiority of proposed TSMSD using PCNN-AA approach as compared to state-of-the-art medical image fusion methods in terms of fusion quality metrics such as entropy (E), mutual information (MI), mean (M), standard deviation (STD), correlation coefficient (CC) and computational complexity.

Multi-scale geometric analysis is a popular tool that is widely used in the field of multi-focus image fusion. It plays a large role in extracting the features from input images. In this paper, a novel multi-focus image fusion method based on a non-fixed-base dictionary and multi-measure optimization is presented in the non-subsampled shearlet transform (NSST) domain. The proposed approach contains the following four steps. The input images are first decomposed by NSST into low- and high-frequency coefficients. Second, a sparse representation (SR)-based framework is proposed and applied to merge the low-frequency coefficients of the input images. In this framework, a non-fixed-base dictionary iteratively trained by the previous dictionary is constructed, which represents the complex details of the source images. Third, a type-2 fuzzy logic scheme is introduced for the high-frequency coefficient fusion, which can effectively select the high-quality coefficients from the source images so that it can achieve better performance. Finally, an inverse NSST operation is conducted in the merged low- and high-pass subbands and thus obtains the initial fused image. A multi-measure optimization method is then employed to optimize the initial fused image, and thus, the final fused result is achieved. In this method, three different measures, namely, pixel difference, visual saliency, and similarity, are designed to select the focus regions more completely. The experimental results demonstrate that our proposed approach yields a better effect than other methods in both the visual quality and the objective assessment.

To preserve more useful information in visible and infrared images and improve the quality of the fused image, a method based on the nonsubsampled shearlet transform (NSST) and fuzzy C-means clustering is proposed. First, the source images are decomposed by NSST so as to get their own low- and high-frequency subbands. Second, the low-frequency subbands are divided into the infrared target part and the background part by fuzzy C-means clustering while different fusion rules are applied to the infrared target part and background part, respectively. Then, a choose-max fusion rule based on the sum-modified Laplacian of source images and local energy of coefficient is proposed to integrate the high-frequency subbands. Finally, the fused image is obtained by inverse NSST. The comparison experiment with the other three state-of-the-art fusion methods shows that the proposed method has good subjective visual effects and superior objective evaluations.

Many fusion methods have been proposed to fuse medical image, but these approaches alway lead to fusion image distortion or image information loss. To overcome the above disadvantages, combined with nonsubsampled shearlet transform (NSST) and spiking cortical model (SCM), a new medical image fusion is proposed. First, NSST is utilized for decomposition of the source images. Secondly, the low and high frequency coefficients of NSST are all fused by fired map of improved SCM (ISCM), which motivated by larger summodified-Laplacian (SML). Finally, the fusion image is gained by inverse NSST. The algorithm can both preserve the information of the source images well and suppress pixel distortion. Experimental results demonstrate that the proposed method outperforms the state-of-the-art fusion methods.

This paper presents a novel multimodal medical image fusion framework (M3IF-NSST-CNN) combining the Non-Subsampled Shearlet Transform (NSST) and deep convolutional neural network (CNN) methods to enhance diagnostic accuracy by effectively integrating Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Initially, both CT and MRI images undergo decomposition via NSST, producing distinct low-pass (LPSB) and high-pass subbands (HPSB). The LPSB fusion leverages a correlation-based approach, ensuring preservation of structural integrity and maximization of complementary information. Concurrently, the HPSB are merged through a Universal Image Quality Index (UIQI)-based fusion rule, prioritizing edge and detail retention critical for precise medical diagnosis. Subsequently, an inverse NSST transforms these fused sub-bands, generating a preliminary fused image. This image is then further refined through a CNN-based noise reduction module comprising convolutional layers, batch normalization, and Rectified Linear Unit (ReLU) activation functions. The deep CNN architecture progressively refines the fused output, significantly reducing artifacts and noise, thus improving the overall clarity and interpretability of the resultant image. This approach addresses common limitations in image fusion, such as loss of edge details, distortion, and the inability to preserve critical information. The hybrid M3IF-NSST-CNN method improves both the visual quality and parametric accuracy of the fusion, outperforming comparable techniques. By preserving more detail and edge information, this method offers significant advancements in multi-modal medical image fusion for enhanced diagnostic insights.

In this study, pulse coupled neural network (PCNN) was modified and applied to the enhancement of blur images. In the transform domain of nonsubsample shearlet transform (NSST), PCNN was used to enhance the details of images in the low- and high-frequency subbands, and then the enhanced low- and high-frequency coefficients were used for NSST inverse transformation to obtain the enhanced images. The results showed that the proposed method can produce higher-quality images and suppress noise better than traditional image enhancement strategies.