2.2.1. Test data collection

To improve the quality and diversity of citrus green fruit images, the modes of the collection were as follows: 1. A manual hand-held camera (Model D7100, APS-C frame camera of Nikon, Japan) was used to take multiangle visible images of citrus green fruits at a distance of 2-3 m from the canopy of the citrus tree, which produced JPEG images with a resolution of 4928×3264; 2. A wireless zoom camera (Hikvision 3T27EWD) was called in the orchard through the cloud platform. This zoom camera has a 1/2.7 largetarget sensor. At a distance of 5-10 m from the canopy of the citrus tree, we used it for remote real-time acquisition of visible images of citrus green fruits, which produced JPEG images with a resolution of 1280×720. The data acquisition mode diagram is shown in Figure 2 . Finally, 200 and 357 citrus green fruit images were collected using the hand-held camera and cloud platform, respectively, for a total of 557 images. The number of citrus green fruits in each image was 1-10. To obtain a unified data format, the picture resolution was compressed to 1280×720. Figure 3 shows citrus green fruit picture data that were collected by the two data collection modes.

Data acquisition mode diagram.

Citrus green fruit images. (A) Pictures of citrus green fruit that were captured with a manual handheld camera and (B) pictures of citrus green fruit that were obtained by the cloud platform.