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In this paper, we propose a general purpose, simple and fast fusion algorithm based on guided image filter. The proposed method can well combine useful source image information into the fused image supported by multi-scale image decomposition, structure transferring property, visual saliency detection, and weight map construction. Multi-scale image decomposition is appropriate to represent and manipulate image features at various scales. Structure transferring property enabled by our algorithm can induce structures of one source image into the other. A new visual saliency detection based on guided image filter introduced in this paper is able to extract significant regions from visually different images of the same scene. The choice of weight maps helped to integrate the complementary information pixel by pixel at each scale. Experimental outcomes of the proposed method are compared and analyzed with traditional and recent guided image filter-based fusion algorithms in terms of visual quality, fusion metrics and run time. In addition, to enhance fusion results further we made an effort to find a suitable image and video enhancement algorithm. The fusion performance analysis clearly indicates that the proposed method is very promising along with less run time.

This work proposes the use of an unmanned aerial vehicle (UAV) with an autopilot to identify the defects present in municipal sewerage pipes. The framework also includes an effective autopilot control mechanism that can direct the flight path of a UAV within a sewer line. Both of these breakthroughs have been addressed throughout this work. The UAV's camera proved useful throughout a sewage inspection, providing important contextual data that helped analyze the sewerage line's internal condition. A plethora of information useful for understanding the sewerage line's inner functioning and extracting interior visual details can be obtained from camera‐recorded sewerage imagery if a defect is present. In the case of sewerage inspections, nevertheless, the impact of a false negative is significantly higher than that of a false positive. One of the trickiest parts of the procedure is identifying defective sewerage pipelines and false negatives. In order to get rid of the false negative outcome or false positive outcome, a guided image filter (GIF) is implemented in this proposed method during the pre‐processing stage. Afterwards, the algorithms Gabor transform (GT) and stroke width transform (SWT) were used to obtain the features of the UAV‐captured surveillance image. The UAV camera's sewerage image is then classified as “defective” or “not defective” using the obtained features by a Weighted Naive Bayes Classifier (WNBC). Next, images of the sewerage lines captured by the UAV are analyzed using speed‐up robust features (SURF) and deep learning to identify different types of defects. As a result, the proposed methodology achieved more favorable outcomes than prior existing approaches in terms of the following metrics: mean PSNR (71.854), mean MSE (0.0618), mean RMSE (0.2485), mean SSIM (98.71%), mean accuracy (98.372), mean specificity (97.837%), mean precision (93.296%), mean recall (94.255%), mean F1‐score (93.773%), and mean processing time (35.43 min). This work describes the construction of an image analysis‐based intelligent information analysis method that will identify issues within municipal sewerage pipes employing an autopilot‐controlled unmanned aerial vehicle (UAV).

This paper presents a novel facial expression recognition (FER) technique based on support vector machine (SVM) for the FER. Here it is called the FERS technique. First, the FERS technique develops a face detection method that combines the Haar-like features method with the self-quotient image (SQI) filter. As a result, the FERS technique possesses better detection rate because the face detection method gets more accurate in locating face regions of an image. The main reason is that the SQI filter can overcome the insufficient light and shade light. Subsequently, three schemes, the angular radial transform (ART), the discrete cosine transform (DCT) and the Gabor filter (GF), are simultaneously employed in the design of the feature extraction for facial expression in the FERS technique. More specifically, they are employed in constructing a set of training patterns for the training of an SVM. The FERS technique then exploits the trained SVM to recognize the facial expression for a query face image. Finally, experimental results show that the recognition performance of the FERS technique can be better than that of other existing methods under consideration in the paper.

An underwater image enhancement technique based on weighted guided filter image fusion is proposed to address challenges, including optical absorption and scattering, color distortion, and uneven illumination. The method consists of three stages: color correction, local contrast enhancement, and fusion algorithm methods. In terms of color correction, basic correction is achieved through channel compensation and remapping, with saturation adjusted based on histogram distribution to enhance visual richness. For local contrast enhancement, the approach involves box filtering and a variational model to improve image saturation. Finally, the method utilizes weighted guided filter image fusion to achieve high visual quality underwater images. Additionally, our method outperforms eight state-of-the-art algorithms in no-reference metrics, demonstrating its effectiveness and innovation. We also conducted application tests and time comparisons to further validate the practicality of our approach.

In the state of the art, grayscale image enhancement algorithms are typically adopted for enhancement of RGB color images captured with low or non-uniform illumination. As these methods are applied to each RGB channel independently, imbalanced inter-channel enhancements (color distortion) can often be observed in the resulting images. On the other hand, images with non-uniform illumination enhanced by the retinex algorithm are prone to artifacts such as local blurring, halos, and over-enhancement. To address these problems, an improved RGB color image enhancement method is proposed for images captured under non-uniform illumination or in poor visibility, based on weighted guided image filtering (WGIF). Unlike the conventional retinex algorithm and its variants, WGIF uses a surround function instead of a Gaussian filter to estimate the illumination component; it avoids local blurring and halo artifacts due to its anisotropy and adaptive local regularization. To limit color distortion, RGB images are first converted to HSI (hue, saturation, intensity) color space, where only the intensity channel is enhanced, before being converted back to RGB space by a linear color restoration algorithm. Experimental results show that the proposed method is effective for both RGB color and grayscale images captured under low exposure and non-uniform illumination, with better visual quality and objective evaluation scores than from comparator algorithms. It is also efficient due to use of a linear color restoration algorithm.

Medical image fusion is a crucial technology for biomedical diagnoses. However, current fusion methods struggle to balance algorithm design, visual effects, and computational efficiency. To address these challenges, we introduce a novel medical image fusion method based on the multi-scale shearing rolling weighted guided image filter (MSRWGIF). Inspired by the rolling guided filter, we construct the rolling weighted guided image filter (RWGIF) based on the weighted guided image filter. This filter offers progressive smoothing filtering of the image, generating smooth and detailed images. Then, we construct a novel image decomposition tool, MSRWGIF, by replacing non-subsampled shearlet transform's non-sampling pyramid filter with RWGIF to extract richer detailed information. In the first step of our method, we decompose the original images under MSRWGIF to obtain low-frequency subbands (LFS) and high-frequency subbands (HFS). Since LFS contain a large amount of energy-based information, we propose an improved local energy maximum (ILGM) fusion strategy. Meanwhile, HFS employ a fast and efficient parametric adaptive pulse coupled-neural network (AP-PCNN) model to combine more detailed information. Finally, the inverse MSRWGIF is utilized to generate the final fused image from fused LFS and HFS. To test the proposed method, we select multiple medical image sets for experimental simulation and confirm its advantages by combining seven high-quality representative metrics. The simplicity and efficiency of the method are compared with 11 classical fusion methods, illustrating significant improvements in the subjective and objective performance, especially for color medical image fusion.

Hyperspectral remote sensing images (HSIs) have both spectral and spatial characteristics. The adept exploitation of these attributes is central to enhancing the classification accuracy of HSIs. In order to effectively utilize spatial and spectral features to classify HSIs, this paper proposes a method for the spatial feature extraction of HSIs based on a mutually guided image filter (muGIF) and combined with the band-distance-grouped principal component. Firstly, aiming at the problem that previously guided image filtering cannot effectively deal with the inconsistent information structure between the guided and target information, a method for extracting spatial features using muGIF is proposed. Then, aiming at the problem of the information loss caused by a single principal component as a guided image in the traditional GIF-based spatial–spectral classification, a spatial feature-extraction framework based on the band-distance-grouped principal component is proposed. The method groups the bands according to the band distance and extracts the principal components of each set of band subsets as the guide map of the current band subset to filter the HSIs. A deep convolutional neural network model and a generative adversarial network model for the filtered HSIs are constructed and then trained using samples for HSIs’ spatial–spectral classification. Experiments show that compared with the traditional methods and several popular spatial–spectral HSI classification methods based on a filter, the proposed methods based on muGIF can effectively extract the spatial–spectral features and improve the classification accuracy of HSIs.

As the mine hoist monitors video images with poor light, low brightness, heavy dust, and low contrast, the monitoring video images are not conducive to monitoring. They cannot meet the needs of applications. Based on actual video surveillance data, this paper proposes a dark channel prior (DCP) method integrated with a guided image filter video image enhancement algorithm. Firstly, we analyzed the characteristics of the mine hoist system’s video images. Then, the DCP technique was used to enhance the video images. A guided image filter algorithm was introduced to ensure that the video has more clarity and visual impact. Comparing the suggested method to the other four algorithms, it performed better both subjectively and objectively than the algorithms mentioned above. Experiments demonstrate that the proposed technique can successfully improve the entire clarity and contrast of video images while avoiding the over-enhancement of bright areas close to the light source, meeting the practical application requirements of video surveillance.

The weighted median filter and the guided image filter are considered important methods for the recently popular variational and non-local total variational optical flow estimation. Their attractive advantages are that outlier reduction is attained, while motion boundaries are preserved. However, these methods still suffer from halo artifacts near edges caused by motion occlusion and illumination changes in adverse outdoor conditions. To overcome these drawbacks, we propose weighted guided filtering with a non-local steering kernel during the coarse-to-fine optical flow estimation. The weighted guided filtering can preserve the motion edges more efficiently by incorporating edge-aware weighting into the filtering process, and the non-local steering kernel can leverage the edge direction more sufficiently. First, we formulate weighted guided filtering with a non-local steering kernel to preserve the edges and improve the robustness of optical flow estimation. Second, we present a combination of median filtering and weighted guided filtering with a non-local steering kernel to optimize the optical flow estimation under the coarse-to-fine process. We compare the proposed method with several state-of-the-art methods using the Middlebury and MPI Sintel test datasets. The results indicate that the proposed method is robust for optical flow estimation and able to preserve motion boundaries.

High spatial resolution multispectral (HMS) images can provide sufficient information for researchers to analyze the potential disasters in the living environment. However, an original multispectral (MS) image is with low-space-resolution and high-spectrum-resolution, while an original panchromatic (PAN) image has the opposite property. Pansharpening aims at obtaining HMS image by retaining spectrum of the MS image and injecting details of the PAN image simultaneously. In this paper, we present a new pansharpening method. First, we use a bilateral filter (BF) to obtain the low-frequency-component (LFC) of PAN and MS images, respectively. Then the high-frequency-component (HFC) of PAN and MS images are readily obtained. Second, an adaptive intensity-hue-saturation (AIHS) based method is applied to generate the HFC of intensity. Finally, a dual-scale guided image filter (GIF) is utilized to calculate the difference between HFC of intensity and PAN to get the detail images. And then, these detail images are injected into the original MS image to achieve the HMS image. The proposed method is applied into testing various satellite data sets, and performs better effect on both visual quality and objective indictors than the existing methods.