Low-light images have low visibility, poor contrast, and weakened details, which pose significant obstacles for subsequent computer vision tasks. When enhancing low-light images, multiple factors such as brightness, contrast, artifacts, and noise need to be considered, making this problem challenging. Low-light enhancement algorithms based on the Retinex theory are important methods in the field of image enhancement, with a wide range of applications and practicality. In this paper, starting from the low-light image imaging model, we address the issues of color distortion and limited brightness improvement exhibited by traditional Retinex-based algorithms and deep learning algorithms in actual low-light scenarios. We propose a filtering and data-driven composite enhancement algorithm (FADDC) that performs weighted fusion on output and intermediate quantities before outputting them. Experimental results combining SCI-Net with traditional algorithms SSR and MSR demonstrate that this fusion method can effectively enhance image brightness without color distortion, achieving better enhancement results.
The current convolution-based semantic segmentation network lacks long-range dependencies for infrared small target detection, which may lead to unsatisfactory detection results in the real scenario. To address the problem, this paper proposed a semantic segmentation network based on hetero-range feature fusion (HRFFnet). Compared with the common semantic segmentation networks, this network includes two feature extraction branches. One is a short-range extraction branch consisting of convolution operations, and the other is a long-range feature extraction branch consisting of transformer. The HRFFnet complements the local features extracted by the convolutional neural network by adding the transformer structure to the segmentation network to introduce the long-range information of image. And this paper also designed a hetero-range fusion module. This module is based on atrous spatial pyramid pooling and adds shortcut connection to fuse different ranges of features extracted from images, which can maintain resolution of image and improve ability of feature representation. The hetero-range fusion module fuses long-range dependencies and short-range information extracted by transformer and convolution to capture multi-scale contextual information about the scene in infrared images and facilitate the interchange of information between different features. To evaluate the HRFFnet, we compare the performance of our network against other high-performance convolution-based methods and transformer-based networks on the open SIRST dataset with different evaluation metrics. The proposed method achieves a better combined results in terms of intersection of Dice coefficient, pixel accuracy, intersection over union and receiver operating characteristic curve. The experiments and results show that the network has some superiority: one is that it can break through the limitation of range of extracting features when only using convolutional network or transformer-based network; the other one is that this network can perform better with good robustness against real and complex scenarios. So, the proposed algorithm has broad application prospects in border patrol and urban security fields.
Synthetic Aperture Radar (SAR) imaging and visible light imaging are the two most commonly used imaging methods for remote sensing satellites. Since the imaging information of the two is highly complementary, many scenarios of data fusion need to use these two heterogeneous data. However, before data fusion, the data of the two modalities need to be aligned, and the performance of heterogeneous data matching algorithm directly affects the performance of obtaining ground control points during alignment. At present, there are many one-stage and two-stage methods for heterogeneous remote sensing image matching. The existing one-stage methods have problems such as large average prediction offset, low matching accuracy, and imbalance of features at different levels when combining features. The stage method cannot meet the actual needs in terms of speed and accuracy. To address these issues, this paper proposes an end-to-end heterogeneous remote sensing image matching framework HB3CF. The framework uses the classic image feature extraction network to construct a pair of pseudo-twin networks, which extract features from two heterogeneous images respectively. Then, the features of each level are uniformly sampled on the channel using the convolution layer to reduce the weight of the high-dimensional features in the joint features, which effectively improves the expression ability of the features of each level of the model. Finally, the matching results are obtained by performing convolution, cross-correlation and up-sampling operations on the high-dimensional features of the SAR image and the optical image. Experiments show that the average offset error of the model is reduced by about 25% compared to state-of-the-art methods. When the average offset error is less than or equal to 0 pixel, 1 pixel, 2 pixel and 3 pixel, the accuracy is increased by 8.53%, 9.54%, 4.16% and 1.12% respectively, reaching 25.90%, 65.03%, 86.65% and 92.15%, which greatly improves the accuracy of the matching method of heterogeneous images, and explores the application of deep learning methods in large-scale heterogeneous remote sensing image matching tasks.
If Toeplitz matrix is used for compression-aware ghost imaging, the imaging quality will be very low. In order to solve the problem, a new experimental scheme for ghost imaging is proposed in this paper. The scheme first extracts the Toeplitz matrix elements randomly and sparsely using a revolving matrix, and then modulates the illumination light field. The sampling is performed by using the Toeplitz matrix as a fixed matrix and another measurement matrix as a revolving matrix. The revolving matrix rotates around its center at a constant angular velocity. The fixed Toeplitz matrix is superimposed with the revolving matrix to form the optical field modulation matrix. The results of simulation experiments show that light field modulation scheme of the rotational random extraction of Toeplitz matrix can modulate the light field with more randomness. The use of this scheme in ghost imaging experiments results in high quality images with low distortion.
Correlated imaging is a research hotspot in recent years. It shows advantages over conventional optical imaging on scanning and imaging rate, noise immunity and so on, and has good application prospects in military electronic reconnaissance and other fields According to the basic principle of polarization correlation imaging, this paper established the spectral polarization BRDF model of rough surface. Taking two typical materials of aluminum alloy and PC plastic as target and background, the effects of wavelength on polarization correlated imaging of rough surface objects is analyzed. Theoretical analysis and simulation results show that the wavelength has little influence on the conventional correlated imaging, and the effects on the polarization correlated imaging appear in complex refractive index, linear polarization and contrast. The wavelength of the best imaging quality can be determined according to different material properties of the set target and the known background.
In order to make the system design meet the requirements of practical ghost imaging, the impact of mechanical vibration on the ghost imaging is analyzed. In ghost imaging system, the light field modulated by a digital micromirror device (DMD) is used to illuminate the target and the transmission or scattering light is detected by a single pixel detector. The target is reconstructed by combining the results of the detector and the intensity distribution of light field, so the modulation matrices of light field play a vital role in ghost imaging. By considering the form of imaging system to vibration and taking the modulation transfer function as an evaluation function, this paper quantitatively analyzes the impacts of various forms of mechanical vibration on the intensity distribution of light field. Combining engineering practice, several solutions are proposed to reduce the impact of vibration on the imaging quality. The results of simulation and experiment indicated that the analysis is correct and usable.
Compressive sensing ghost imaging (CSGI) is an imaging mechanism that can nonlocally obtain an unknown object’s information with a single-pixel detector by the correlation of intensity fluctuations. In the practical research and application of CSGI, object detection plays a crucial role in real-time monitoring and dynamic optimization of speckle pattern. We demonstrate, for the first time to our knowledge, how to solve the low-resolution and undersampling problems in CSGI object detection. The method we use is to combine generative adversarial networks (GANs) with object detection systems. The robustness of the object detection model can increase by generating reconstructed images of different resolutions and sampling rates for training. The experiment results have verified that the mean average precision of CSGI object detection using GANs has been improved 16.48% and 2.98% on MSCOCO 2017 compared with two traditional learning methods, respectively.
Ghost imaging is an imaging mechanism that can non-locally obtain an unknown object’s information with a single-pixel detector by the correlation of intensity fluctuations. To overcome the drawback of polarization compressive ghost imaging (PCGI), here we develop a novel adaptive polarization compressive ghost imaging (APCGI) method. By performing principal component analysis of the polarization statistics, we can compute the optimum unequal weighting coefficients forming as linear combinations of the light into bucket detectors. The specific steps of APCGI include calculating complete polarization parameters on the background, performing principal components analysis for optimal parameters, obtaining the information on the target-with-background scene. Experimental results demonstrate that adaptive polarization compressive ghost imaging performs better in restraining the background and pop out the details of targets as well as obtains better image quality.
Ghost imaging is an indirect system that allows the imaging of an object without directly seeing the object. The speckle pattern that contains the information about light and objects has increasingly become a popular topic in pseudothermal light ghost imaging. However, existing research still has encountered problems of poor imaging quality and slow sampling speeds. We propose a ghost imaging method based on N-order speckle patterns to recover the object (NSGI). The N-order speckle patterns combine N independent laser speckles individually produced by passing an expanded and collimated He–Ne laser through a digital micromirror device (DMD). The sampling frequency can be improved by controlling the trigger signals of different DMDs. The results of the simulation and experiment have verified that our method can increase sampling speed and reconstruction accuracy. In addition, NSGI can be applied to more applications by designing multiple independent speckles with different properties.
As a new imaging mechanism, ghost imaging has become a hot area of research in optical imaging field. In this paper, the effect of intensity correlation order on lensless ghost imaging system is investigated. We demonstrate that the image quality of Nth-order ghost imaging and Nth-order ghost imaging with background subtraction can be affected by the different intensity correlation order of test light and reference both theoretically and experimentally. The result indicates that the image quality will not be certainly increased with the increasing of the intensity correlation order, and here will be very useful for choosing an appropriate intensity correlation order in practice.
Sparse decomposition is one of the core issue of compressive sensing ghost image. At this stage, traditional
methods still have the problems of poor sparsity and low reconstruction accuracy, such as discrete fourier transform and
discrete cosine transform. In order to solve these problems, joint orthogonal bases transform is proposed to optimize
ghost imaging. First, introduce the principle of compressive sensing ghost imaging and point out that sparsity is related
to the minimum sample data required for imaging. Then, analyze the development and principle of joint orthogonal
bases in detail and find out it can use less nonzero coefficients to reach the same identification effect as other methods.
So, joint orthogonal bases transform is able to provide the sparsest representation. Finally, the experimental
setup is built in order to verify simulation results. Experimental results indicate that the PSNR of joint orthogonal bases
is much higher than traditional methods by using same sample data in compressive sensing ghost image.Therefore, joint
orthogonal bases transform can realize better imaging quality under less sample data, which can satisfy the system
requirements of convenience and rapid speed in ghost image.
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