MEAN-SSD: A novel real-time detector for apple leaf diseases using improved light-weight convolutional neural networks

Alternaria blotch, Brown spot, Mosaic, Grey spot, and Rust are 5 common apple leaf diseases that severely impact apple production and quality. At present, although many CNN methods have been proposed for apple leaf diseases, there are still lack of apple leaf disease detection models that can be applied on mobile devices, which limits their application in practical production. This paper proposes a light-weight CNN model that can be deployed on mobile devices to detect apple leaf diseases in real time. First, a dataset of apple leaf diseases composed of simple background images and complex background images, which is called AppleDisease5, is constructed via data augmentation technology and data annotation technology. Then a basic module called MEAN block(Mobile End AppleNet block) is proposed to increase the detection speed and reduce model’s size by reconstructing the common 3×3 convolution. Meanwhile, the Apple-Inception module is built by introducing GoogLeNet’s Inception module and replacing all 3×3 convolution kernels with MEAN block in Inception. Finally, a new apple leaf disease detection model, MEAN-SSD(Mobile End AppleNet based SSD algorithm), is built by using the MEAN block and Apple-Inception module. The experiment results show that MEAN-SSD can achieve the detection performance of 83.12% mAP and a speed of 12.53 FPS, which illustrates that the novel MEAN-SSD model can efficiently and accurately detect 5 common apple leaf diseases on mobile devices.