Bacterial colonies detecting and counting based on enhanced CNN detection method

¹ Qilu University of Technology (Shandong Academy of Sciences), Institute of Oceanographic Instrumentation, 37 Miaoling Road, Qingdao, China, 266100
² Shandong Provincial Key Laboratory of Marine monitoring instrument equipment technology, 37 Miaoling Road, Qingdao, China, 266100
³ National Engineering and Technological Research Center of Marine Monitoring Equipment, 37 Miaoling Road, Qingdao, China, 266100

^* Corresponding author: zhiganggai@126.com (Z. Gai); xss_qd@126.com (S. Xu)

Abstract

Bacterial colonies detecting and counting is tedious and time-consuming work. Fortunately CNN (convolutional neural network) detection methods are effective for target detection. The bacterial colonies are a kind of small targets, which have been a difficult problem in the field of target detection technology. This paper proposes a small target enhancement detection method based on double CNNs, which can not only improve the detection accuracy, but also maintain the detection speed similar to the general detection model. The detection method uses double CNNs. The first CNN uses SSD_MOBILENET_V1 network with both target positioning and target recognition functions. The candidate targets are screened out with a low confidence threshold, which can ensure no missing detection of small targets. The second CNN obtains candidate target regions according to the first round of detection, intercepts image sub-blocks one by one, uses the MOBILENET_V1 network to filter out targets with a higher confidence threshold, which can ensure good detection of small targets. Through the two-round enhancement detection method has been transplanted to the embedded platform NVIDIA Jetson AGX Xavier, the detection accuracy of small targets is significantly improved, and the target error detection rate and missed detection rate are reduced to less than 1%.