What is the difference between "SPPF/SPP -> C3" and "C3 -> SPPF/SPP" in backbone ?

[sunshanlu]

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Question

Hello, I found that the last two layers of the backbone of the configuration file of version v5.0 of YOLOv5 use "C3 -> SPP", while the configuration file of version v6.0 uses "C3-> SPPF". I would like to ask what is the reason for this? Thank you.

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[UltralyticsAssistant]

👋 Hello @sunshanlu, thank you for your interest in YOLOv5 🚀! This is an automated response to assist you while an Ultralytics engineer reviews your question.

Regarding your query about the differences between "SPPF/SPP -> C3" and "C3 -> SPPF/SPP" in different YOLOv5 versions, this pertains to architectural changes aimed at improving model performance and efficiency.

For detailed explanations on updates and improvements between versions, you can refer to the YOLOv5 release notes and documentation in the repository. Meanwhile, if you have any specific questions about these layers or their configurations, feel free to provide more details, and an Ultralytics engineer will assist you soon. 😊

If this is a 🔄 follow-up question, please include the context or examples that can help us provide a more accurate answer.

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[pderrenger]

@sunshanlu the change from "C3 -> SPP" in YOLOv5 v5.0 to "C3 -> SPPF" in v6.0 is primarily due to performance improvements. The SPPF (Spatial Pyramid Pooling - Fast) module replaces SPP to enhance processing speed while maintaining similar functionality. SPPF is designed to be more efficient, significantly reducing the processing time. You can find more details about this change in the YOLOv5 architecture documentation.