Academic Journal of Science and Technology ISSN: 2771-3032 | Vol. 14, No. 1, 2025 150 Image Recognition Method for Corn Northern Leaf Blight of Unmanned Aerial Vehicles Based on Deep Learning Xianyuan Liu, Wei Su Jilin Institute of Chemical Technology, Jilin 132000, China Abstract: Aiming at the problems of high complexity, false detection and missing detection of maize big spot based on UAV image, an improved algorithm for maize big spot detection was proposed. The algorithm is based on EMA and the improved YOLOv8-BiFPN feature pyramid network. By adding the efficient multi-scale EMA attention mechanism module, the capturing ability of detail information is improved, thus enhancing the feature extraction ability of the model. The YOLOv8 structure is improved into YOLOV8-BIFPN feature pyramid network by integrating BiFPN structure, which can extract context information more efficiently. By introducing WloU loss function, low quality samples in training data are filtered effectively, and the generalization ability of the model is improved. In this paper, the accuracy P was increased by 2.7%, the recall rate R was increased by 4.7%, the average accuracy mAP50 was increased by 3.1%, and the model size was reduced by 2.78M. Compared with other YOLO algorithms, the proposed method has significant advantages in the detection of corn big spot disease. Keywords: EMA Attention Mechanism; UAV image; YOLOv8-BiFPN; Corn Large Spot Disease. 1. Introduction In China's agricultural structure, corn is the largest crop, accounting for nearly 40% of the total grain output, with a planting area of 650 million mu. It is the foundation of grain production, the link between crop cultivation and breeding, more than 60% of its output is used for the production of feed, and it plays an important role in the economy, sustainable agriculture, and the development of rural livelihoods, and is also key to ensuring food security and promoting sustainable social and economic development. However, in recent years, the frequent occurrence of corn diseases, especially the large spot disease, poses a major threat to corn leaves, affecting photosynthesis and thus threatening the yield and quality of corn. Due to the inefficiency, high cost, subjectivity, and lack of timeliness of traditional manual detection methods, machine vision technology is introduced to achieve rapid and effective identification of diseases, thereby formulating control measures to reduce the negative impact of diseases, ensuring food security, and promoting sustainable agricultural development. With the development and cost reduction of UAV technology, its flexibility and accessibility have been widely applied in various fields, and its aerial photography images play an important role in target detection. Combined with machine vision technology, it can achieve rapid and effective disease detection, providing innovative scientific and technological means for agricultural production. At present, YOLOv8, as a more advanced target detection model, has shown great potential in the agricultural field, especially in crop disease detection. Lu et al. proposed the YOLOv8_Rice model, which significantly improved the recognition ability of small-sized and irregularly shaped disease types by optimizing the attention mechanism and introducing deformable convolution. In addition, He et al. proposed the EDS-YOLOv8 algorithm, which significantly improved the accuracy of dense weed detection. Sun et al. proposed a lightweight network to improve the YOLOv8 model, effectively reducing the model's parameter volume and computational complexity while maintaining accuracy in the detection of tobacco pests in complex environments. Deng Pengfei et al. used the fusion structure of Inception and VGG as the feature extraction model, and compressed the model through transfer learning, channel pruning, and knowledge distillation, achieving rapid identification of corn diseases. Ye et al. proposed an improved YOLOv8 lightweight pest image recognition model, which significantly improved the performance of small target detection by introducing BiFormer attention mechanism and GELAN network. Liu et al. proposed a feature-enhanced detection algorithm based on SSD, integrating the residual structure of the ResNet50 network into the backbone network, improving the detection ability for small targets. The YOLOv8 model has also been applied to agricultural resource monitoring and yield estimation. Yu et al. proposed a model based on improved YOLOv8, using PConv technology to improve model detection accuracy in complex situations. With the development of agricultural automation and intelligence, the application of YOLOv8 algorithm models in agricultural robots and intelligent agricultural equipment is also becoming more and more widespread. Guo et al. used the improved YOLOv8 algorithm model to achieve early detection of harmful plants by combining multi-source image data. Zhu Qi et al. proposed a DSCS-YOLO-based apple surface defect detection method, designed a DSCS shallow- deep feature selection module based on the Dense module and SE module, improved the original decoupling head with ELU activation function, and used the Wise-IoU loss function for nonlinear gain, achieving dynamic focused learning of the network. Liu et al. proposed a lightweight apple detection algorithm Faster-YOLO-AP based on improved YOLOv8, which is specifically designed for edge computing devices to achieve real-time object detection. Wang et al. proposed a YOLOv8+ model for strawberry maturity detection and classification, providing technical support for intelligent harvesting systems. Zhang et al. improved the YOLOv8 151 algorithm by introducing Mish activation function and DenseBlock structure, improving the accuracy and robustness of agricultural pest and disease detection. Zhu et al. proposed the Poly-YOLOv8 model and designed a new loss calculation algorithm, improving the model's detection ability for polygonal targets. The aforementioned methods have some issues with real- time and accuracy in detection speed and model precision. In response to these issues, this paper improves the YOLOv8n as the benchmark algorithm to achieve UAV image corn large spot disease detection, and the main improvements and innovations to the YOLOv8 algorithm are as follows: first, a new attention mechanism module is introduced to improve recognition accuracy, then the new feature pyramid network structure adopts cross-scale connection methods and weighted feature methods to effectively integrate multi-scale features, fully solving the problem of large scale differences and feature loss, in addition, the introduction of a new loss function effectively reduces the negative impact of low- quality samples, further enhancing the model's generalization performance. 2. Improved YOLOv8 Algorithm The YOLOv8 algorithm is known for its fast speed and high accuracy, and has been widely applied. The innovation of the YOLOv8 model structure first uses a deep convolutional neural network as its feature extractor, which greatly helps in capturing richer image features. At the same time, multi-scale feature fusion technology is introduced into the algorithm, making it more effective in handling targets of different sizes and improving the algorithm's ability to detect small targets. YOLOv8 also optimizes the loss function by introducing new regularization terms and adjusting the predicted bounding box, further improving the accuracy of detection. YOLOv8 has achieved simultaneous improvement in recognition speed and detection accuracy through these improvements. The optimization of YOLOv8 has achieved good results in target detection tasks. 2.1. Maize Large Spot Disease Recognition Algorithm Model To improve the detection accuracy of maize large spot disease, this paper proposes an improved optimization plan based on the YOLOv8 network architecture. The model is based on the YOLOv8 base algorithm and is improved and optimized, as shown in Figure 1. Figure 1. Improved and optimized YOLOv8 network structure The specific improvements of the improved model compared to the pre-improved model are as follows. Backbone Network: Three multi-scale attention EMA modules are introduced to capture detail information and improve the model's feature extraction capability, while retaining the original SPPF module in the model, which can solve the problem of repeated feature extraction of images by convolutional neural networks, speed up the generation of candidate boxes, and save computational costs. Neck Network: A lightweight YOLOv8-BiFPN feature pyramid network structure is proposed by fusing BiFPN and the original YOLOv8 structure to enhance the model's multi- scale feature fusion capability and improve the network's detection accuracy for small targets. 152 Head Network: The original network loss function is optimized with WIoU Loss, introducing a dynamic non- monotonic focusing mechanism to improve the model's generalization capability. In summary, this design method improves the existing algorithm, achieving high detection speed and model lightweight while improving detection accuracy, thereby enhancing the extraction capability of maize large spot disease features and enhancing the stability of the detection process. 2.2. Backbone Network Improvement. By introducing the EMA (Efficient Multi-Scale Attention) attention module, the ability of the attention mechanism to obtain local important information is improved. EMA, as a multi-scale efficient attention mechanism, reshapes the channel dimension while maintaining the original channel dimension, improving computational ability while minimizing the loss of channel information. EMA is mainly responsible for global information encoding, can manage the channel weights of multiple parallel subnetworks, and promotes cross-dimensional information integration between these subnetworks, thereby producing output features. Its structure is shown in Figure 2. When the input features C H WR  X are divided into N sub-features   C//C H 0 1, , , R W i N i    X X X X X according to the EMA channel number, let N<