Y. Huilian, L. Jundi, and S. Weiping, Analysis on apple production, processing, trade and consumption situation in major apple producing countries, Northern Horticulture?2015, pp.166-169

X. Xue, Q. Yun, and W. Jian, Research status and prospect of apple detection and localization methods under orchard environment, J]. Journal of Agricultural Science and Technology?2017?19, issue.2, pp.65-74

. Zhou-guomin, Research and development of digital orchard in China

, Agriculture Network Information?2012, issue.1, pp.10-12

. Zhou-guomin, Application Situation and Outlook of Digital Orchard, J].Agricultural, vol.2012, issue.1, pp.10-12

K. Yamamoto, W. Guo, and Y. Yoshioka, On plant detection of intact tomato fruits using image analysis and machine learning methods, Sensors, vol.14, issue.7, pp.12191-12206, 2014.

S. Chaivivatrakul and M. Dailey, Texture-based fruit detection, Precision Agriculture, vol.15, pp.662-683, 2014.

F. Longsheng, W. Bin, and C. Yongjie, Kiwifruit recognition at nighttime using artificial lighting based on machine vision, International Journal of Agricultural and Biological Engineering, vol.8, issue.4, pp.52-59, 2015.

C. Mccool, I. Sa, and F. Dayoub, Visual detection of occluded crop: For automated harvesting[C]//Robotics and Automation (ICRA), IEEE, pp.2506-2512, 2016.

D. Bulanon, T. Kataoka, and Y. Ota, A segmentation algorithm for the automatic recognition of Fuji apples at harvest, Biosystems Engineering, vol.83, issue.4, pp.405-412, 2002.

L. Huang, D. He, and S. X. Yang, Segmentation on ripe Fuji apple with fuzzy 2D entropy based on 2D histogram and GA optimization, J]. Intelligent Automation & Soft Computing, vol.19, issue.3, pp.239-251, 2013.

D. Kim, H. Choi, and J. Choi, A Novel Red Apple Detection Algorithm Based on AdaBoost Learning, IEIE Transactions on Smart Processing & Computing, vol.4, issue.4, pp.265-271, 2015.

Q. Jianping, Y. Xinting, and W. Xiaoming, Mature apple recognition based on hybrid color space in natural scene, Transactions of the Chinese Society of Agricultural Engineering, vol.28, pp.137-142, 2012.

J. Rakun, D. Stajnko, and D. Zazula, Detecting fruits in natural scenes by using spatial-frequency based texture analysis and multiview geometry, Computers and Electronics in Agriculture, vol.76, issue.1, pp.80-88, 2011.

R. Linker, O. Cohen, and A. Naor, Determination of the number of green apples in RGB images recorded in orchards, Computers and Electronics in Agriculture, pp.45-57, 201281.

Z. Chunlong, Z. Ji, and Z. Junxiong, Recognition of green apple in similar background, Transactions of the Chinese Society for Agricultural Machinery, pp.277-281, 201445.

S. Yongsheng, L. Gang, and G. Rui, Segmentation algorithm for green apples recognition based on K-means algorithm, Transactions of the Chinese Society for Agricultural Machinery, pp.100-104, 200940.

C. Yongjie, S. Shuai, and W. Xiaxia, Recognition and feature extraction of kiwifruit in natural environment based on machine vision, Transactions of the Chinese Society for Agricultural Machinery, pp.247-252, 201344.

L. Drever, W. Roa, and A. Mcewan, Iterative threshold segmentation for PET target volume delineation, J]. Medical physics, vol.34, issue.4, pp.1253-1265, 2007.

S. Sengupta and W. S. Lee, Identification and determination of the number of immature green citrus fruit in a canopy under different ambient light conditions, Biosystems Engineering, vol.117, pp.51-61, 2014.

M. Smereka and I. Duleba, Circular Object Detection Using a Modified Hough Transform, J]. Applied Mathematics and Computer Science, vol.18, issue.1, pp.85-91, 2008.

T. Atherton and D. J. Kerbyson, Size invariant circle detection, vol.17, pp.795-803, 1999.

E. Davies, Computer and machine vision: theory, algorithms

N. Dalal and B. Triggs, Histograms of oriented gradients for human detection[C]//Computer Vision and Pattern Recognition, IEEE Computer Society Conference on. IEEE, vol.1, pp.886-893, 2005.

. Hu-qingxin, W. Peng, and . Xiaxia, Pedestrian detection in infrared images based on multi-feature fusion, J]. Journal of Computer Applications, issue.A01, pp.157-160, 201336.

A. Gavriilidis, C. Stahlschmidt, and J. Velten, Feature Recycling Cascaded SVM Classifier Based on Feature Selection of HOGs for Pedestrian Detection, /International Conference on Multimedia Communications, Services and Security, pp.82-94, 2013.

M. Chunyan, Z. Lihua, and X. Changyi, Comparison of apple recognition methods under natural light, Journal of China Agricultural University, issue.11, pp.43-50, 201621.

V. Vpnik, A. Chervonenkis, and . Ja, Theoey of Pattern Recognition, 1974.

W. Can and L. Zhiwei, Weed recognition using SVM model with fusion height and monocular image features, Transactions of the Chinese Society of Agricultural Engineering, vol.32, pp.165-174, 2016.

H. Chen and F. Jiyou, Online apple grading based on decision fusion of image features, Transactions of the Chinese Society of Agricultural Engineering, vol.33, pp.285-291, 2017.