# Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license

# Ultralytics YOLO26 object detection model with P3/8 - P6/64 outputs
# Model docs: https://docs.ultralytics.com/models/yolo26
# Task docs: https://docs.ultralytics.com/tasks/detect

# Parameters
nc: 80 # number of classes
end2end: True # whether to use end-to-end mode
reg_max: 1 # DFL bins
scales: # model compound scaling constants, i.e. 'model=yolo26n-p6.yaml' will call yolo26-p6.yaml with scale 'n'
  # [depth, width, max_channels]
  n: [0.50, 0.25, 1024] # summary: 349 layers, 4,063,872 parameters, 4,063,872 gradients, 6.0 GFLOPs
  s: [0.50, 0.50, 1024] # summary: 349 layers, 15,876,448 parameters, 15,876,448 gradients, 22.3 GFLOPs
  m: [0.50, 1.00, 512] # summary: 369 layers, 32,400,096 parameters, 32,400,096 gradients, 77.3 GFLOPs
  l: [1.00, 1.00, 512] # summary: 523 layers, 39,365,600 parameters, 39,365,600 gradients, 97.0 GFLOPs
  x: [1.00, 1.50, 512] # summary: 523 layers, 88,330,368 parameters, 88,330,368 gradients, 216.6 GFLOPs

# YOLO26n backbone
backbone:
  # [from, repeats, module, args]
  - [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
  - [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
  - [-1, 2, C3k2, [256, False, 0.25]]
  - [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
  - [-1, 2, C3k2, [512, False, 0.25]]
  - [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
  - [-1, 2, C3k2, [512, True]]
  - [-1, 1, Conv, [768, 3, 2]] # 7-P5/32
  - [-1, 2, C3k2, [768, True]]
  - [-1, 1, Conv, [1024, 3, 2]] # 9-P6/64
  - [-1, 2, C3k2, [1024, True]]
  - [-1, 1, SPPF, [1024, 5]] # 11
  - [-1, 2, C2PSA, [1024]] # 12

# YOLO26n head
head:
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 8], 1, Concat, [1]] # cat backbone P5
  - [-1, 2, C3k2, [768, True]] # 15

  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 6], 1, Concat, [1]] # cat backbone P4
  - [-1, 2, C3k2, [512, True]] # 18

  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 4], 1, Concat, [1]] # cat backbone P3
  - [-1, 2, C3k2, [256, True]] # 21 (P3/8-small)

  - [-1, 1, Conv, [256, 3, 2]]
  - [[-1, 18], 1, Concat, [1]] # cat head P4
  - [-1, 2, C3k2, [512, True]] # 24 (P4/16-medium)

  - [-1, 1, Conv, [512, 3, 2]]
  - [[-1, 15], 1, Concat, [1]] # cat head P5
  - [-1, 2, C3k2, [768, True]] # 27 (P5/32-large)

  - [-1, 1, Conv, [768, 3, 2]]
  - [[-1, 12], 1, Concat, [1]] # cat head P6
  - [-1, 1, C3k2, [1024, True, 0.5, True]] # 30 (P6/64-large)

  - [[21, 24, 27, 30], 1, Detect, [nc]] # Detect(P3, P4, P5, P6)