This study introduces a new dense pest counting problem to predict densely distributed pests captured by digital traps. Unlike traditional detection‐based counting models for sparsely distributed objects, trap‐based pest counting must deal with dense pest distributions that pose challenges such as severe occlusion, wide pose variation, and similar appearances in colors and textures. To address these problems, it is essential to incorporate the local attention mechanism, which identifies locally important and unimportant areas to learn locally grouped features, thereby enhancing discriminative performance. Accordingly, this study presents a novel design that integrates locally grouped and scale‐guided attention into a multiscale CenterNet framework. To group local features with similar attributes, a straightforward method is introduced using the heatmap predicted by the first hourglass containing pest centroid information, which eliminates the need for complex clustering models. To enhance attentiveness, the pixel attention module transforms the heatmap into a learnable map. Subsequently, scale‐guided attention is deployed to make the object and background features more discriminative, achieving multiscale feature fusion. Through experiments, the proposed model is verified to enhance object features based on local grouping and discriminative feature attention learning. Additionally, the proposed model is highly effective in overcoming occlusion and poses variation problems, making it more suitable for dense pest counting. In particular, the proposed model outperforms state‐of‐the‐art models by a large margin, with a remarkable contribution to dense pest counting. To be specific, the proposed model can improve accuracy by approximately 1058.2%, 90.8%, and 31.3% in terms of mean absolute error (MAE) compared with Faster RCNN, YOLOv7, and multiscale CenterNet, respectively, for a uniform dataset.

Generative adversarial network (GAN)-based methods recover perceptually pleasant details in super resolution (SR), but they pertain to structural distortions. Recent study alleviates such structural distortions by attaching a gradient branch to the generator. However, this method compromises the perceptual details. In this paper, we propose a sparse gradient-guided attention generative adversarial network (SGAGAN), which incorporates a modified residual-in-residual sparse block (MRRSB) in the gradient branch and gradient-guided self-attention (GSA) to suppress structural distortions. Compared to the most frequently used block in GAN-based SR methods, i.e., residual-in-residual dense block (RRDB), MRRSB reduces computational cost and avoids gradient redundancy. In addition, GSA emphasizes the highly correlated features in the generator by guiding sparse gradient. It captures the semantic information by connecting the global interdependencies of the sparse gradient features in the gradient branch and the features in the SR branch. Experimental results show that SGAGAN relieves the structural distortions and generates more realistic images compared to state-of-the-art SR methods. Qualitative and quantitative evaluations in the ablation study show that combining GSA and MRRSB together has a better perceptual quality than combining self-attention alone.

Different from conventional haze removal methods based on a single image, near-infrared imaging can provide two types of multimodal images: one is the near-infrared image and the other is the visible color image. These two images have different characteristics regarding color and visibility. The captured near-infrared image is haze-free, but it is grayscale, whereas the visible color image has colors, but it contains haze. There are serious discrepancies in terms of brightness and image structures between the near-infrared image and the visible color image. Due to this discrepancy, the direct use of the near-infrared image for haze removal causes a color distortion problem during near-infrared fusion. The key objective for the near-infrared fusion is therefore to remove the color distortion as well as the haze. To achieve this objective, this paper presents a new near-infrared fusion model that combines the proposed new color and depth regularizations with the conventional haze degradation model. The proposed color regularization sets the color range of the unknown haze-free image based on the combination of the two colors of the colorized near-infrared image and the captured visible color image. That is, the proposed color regularization can provide color information for the unknown haze-free color image. The new depth regularization enables the consecutively estimated depth maps not to be largely deviated, thereby transferring natural-looking colors and high visibility of the colorized near-infrared image into the preliminary dehazed version of the captured visible color image with color distortion and edge artifacts. Experimental results show that the proposed color and depth regularizations can help remove the color distortion and the haze simultaneously. The effectiveness of the proposed color regularization for the near-infrared fusion is verified by comparing it with other conventional regularizations.

Near-infrared imaging has been considered as a solution to provide high quality photographs in dim lighting conditions. This imaging system captures two types of multimodal images: one is near-infrared gray image (NGI) and the other is the visible color image (VCI). NGI is noise-free but it is grayscale, whereas the VCI has colors but it contains noise. Moreover, there exist serious edge and brightness discrepancies between NGI and VCI. To deal with this problem, a new transfer-based fusion method is proposed for noise removal. Different from conventional fusion approaches, the proposed method conducts a series of transfers: contrast, detail, and color transfers. First, the proposed contrast and detail transfers aim at solving the serious discrepancy problem, thereby creating a new noise-free and detail-preserving NGI. Second, the proposed color transfer models the unknown colors from the denoised VCI via a linear transform, and then transfers natural-looking colors into the newly generated NGI. Experimental results show that the proposed transfer-based fusion method is highly successful in solving the discrepancy problem, thereby describing edges and textures clearly as well as removing noise completely on the fused images. Most of all, the proposed method is superior to conventional fusion methods and guided filtering, and even the state-of-the-art fusion methods based on scale map and layer decomposition.

Near-infrared gray images captured along with corresponding visible color images have recently proven useful for image restoration and classification. This paper introduces a new coloring method to add colors to near-infrared gray images based on a contrast-preserving mapping model. A naive coloring method directly adds the colors from the visible color image to the near-infrared gray image. However, this method results in an unrealistic image because of the discrepancies in the brightness and image structure between the captured near-infrared gray image and the visible color image. To solve the discrepancy problem, first, we present a new contrast-preserving mapping model to create a new near-infrared gray image with a similar appearance in the luminance plane to the visible color image, while preserving the contrast and details of the captured near-infrared gray image. Then, we develop a method to derive realistic colors that can be added to the newly created near-infrared gray image based on the proposed contrast-preserving mapping model. Experimental results show that the proposed new method not only preserves the local contrast and details of the captured near-infrared gray image, but also transfers the realistic colors from the visible color image to the newly created near-infrared gray image. It is also shown that the proposed near-infrared coloring can be used effectively for noise and haze removal, as well as local contrast enhancement.

Recently, image pairs, such as noisy and blurred images or infrared and noisy images, have been considered as a solution to provide high-quality photographs under low lighting conditions. In this paper, a new method for decomposing the image pairs into two layers, i.e., the base layer and the detail layer, is proposed for image pair fusion. In the case of infrared and noisy images, simple naive fusion leads to unsatisfactory results due to the discrepancies in brightness and image structures between the image pair. To address this problem, a local contrast-preserving conversion method is first proposed to create a new base layer of the infrared image, which can have visual appearance similar to another base layer, such as the denoised noisy image. Then, a new way of designing three types of detail layers from the given noisy and infrared images is presented. To estimate the noise-free and unknown detail layer from the three designed detail layers, the optimization framework is modeled with residual-based sparsity and patch redundancy priors. To better suppress the noise, an iterative approach that updates the detail layer of the noisy image is adopted via a feedback loop. This proposed layer-based method can also be applied to fuse another noisy and blurred image pair. The experimental results show that the proposed method is effective for solving the image pair fusion problem.

Modulating the orientation of elliptically clustered dots in each halftone cell enables binary data to be embedded into the clustered halftone dots. In this paper, a new decoding method is proposed for recovering hidden binary data from clustered halftone dots by using learned dictionaries, which are optimized to represent clustered dots with different elliptical shapes. The basic idea is that the reconstruction errors of the clustered dots in a halftone cell are differentiable according to the dictionaries used. The experimental results showed that determining which of the learned dictionaries provides a minimum reconstruction error in a halftone cell can reveal the orientation of the clustered dots and thus indicate the embedded binary data. The experiment results also showed that the proposed decoding method can be applied to other types of clustered halftone dots to infer hidden binary data.

A method is proposed for fully restoring local image structures of an unknown continuous-tone patch from an input halftoned patch with homogenously distributed dot patterns, based on a locally learned dictionary pair via feature clustering. First, many training sets consisting of paired halftone and continuous-tone patches are collected, and then histogram-of- oriented-gradient (HOG) feature vectors that describe the edge orientations are calculated from every continuous-tone patch, to group the training sets. Next, a dictionary learning algorithm is separately conducted on the categorized training sets, to obtain the halftone and continuous-tone dictionary pairs, optimized to edge-oriented patch representation. Finally, an adaptively smoothing filter is applied to the input halftone patch, to predict the HOG feature vector of an unknown continuous-tone patch, and to select one of the previously learned dictionary pairs, based on the Euclidean distance between the HOG mean feature vectors of the grouped training sets and the predicted HOG vector. In addition to using the local dictionary pairs, a patch fusion technique is used to reduce some artifacts, such as color noise and overemphasized edges on smooth regions. Experimental results show that the use of the paired dictionary selected by the local edge orientation and patch fusion technique not only reduced the artifacts in smooth regions, but also provided well expressed fine details and outlines, especially in the areas of textures, lines, and regular patterns.

This paper proposes a colorimetric characterization method using the color correlation between the colorants in a hi-fi printer. While several colorant combinations can be used to match a certain color stimulus in a hi-fi printing system with more than 3 colorants, conventional colorimetric characterization methods only use 3 or 4 colorants to render a color, thereby limiting the color representation. As a result, the gamut is limited as they give up the other combinations of colorants. Therefore, this paper proposes a method of colorimetric characterization that uses combinations of all the colorants. As such, certain colorant combinations are selected based on considering the correlation factor between the colorant amount distributions. The correlation factor also affects the interpolation error, as the colorants are not independent of each other. Consequently, the total gamut is increased in low lightness regions, and the colors are represented more accurately.

Mobile displays such as PDAs and cellular phones can be placed under various illumination levels, different from the flat panel displays mainly used in the indoor environment. In particular, in the daylight condition, the displayed images or text on a mobile display can be darkly perceived, i.e., the degradation of sunlight-readability. In this paper, we consider why this kind of problem occurs in mobile phones and suggest the illumination level adaptive color reproduction method with lightness adaptation model and flare compensation.