Add TensorFlow and TFLite export (#1127)

* Add models/tf.py for TensorFlow and TFLite export

* Set auto=False for int8 calibration

* Update requirements.txt for TensorFlow and TFLite export

* Read anchors directly from PyTorch weights

* Add --tf-nms to append NMS in TensorFlow SavedModel and GraphDef export

* Remove check_anchor_order, check_file, set_logging from import

* Reformat code and optimize imports

* Autodownload model and check cfg

* update --source path, img-size to 320, single output

* Adjust representative_dataset

* Put representative dataset in tfl_int8 block

* detect.py TF inference

* weights to string

* weights to string

* cleanup tf.py

* Add --dynamic-batch-size

* Add xywh normalization to reduce calibration error

* Update requirements.txt

TensorFlow 2.3.1 -> 2.4.0 to avoid int8 quantization error

* Fix imports

Move C3 from models.experimental to models.common

* Add models/tf.py for TensorFlow and TFLite export

* Set auto=False for int8 calibration

* Update requirements.txt for TensorFlow and TFLite export

* Read anchors directly from PyTorch weights

* Add --tf-nms to append NMS in TensorFlow SavedModel and GraphDef export

* Remove check_anchor_order, check_file, set_logging from import

* Reformat code and optimize imports

* Autodownload model and check cfg

* update --source path, img-size to 320, single output

* Adjust representative_dataset

* detect.py TF inference

* Put representative dataset in tfl_int8 block

* weights to string

* weights to string

* cleanup tf.py

* Add --dynamic-batch-size

* Add xywh normalization to reduce calibration error

* Update requirements.txt

TensorFlow 2.3.1 -> 2.4.0 to avoid int8 quantization error

* Fix imports

Move C3 from models.experimental to models.common

* implement C3() and SiLU()

* Fix reshape dim to support dynamic batching

* Add epsilon argument in tf_BN, which is different between TF and PT

* Set stride to None if not using PyTorch, and do not warmup without PyTorch

* Add list support in check_img_size()

* Add list input support in detect.py

* sys.path.append('./') to run from yolov5/

* Add int8 quantization support for TensorFlow 2.5

* Add get_coco128.sh

* Remove --no-tfl-detect in models/tf.py (Use tf-android-tfl-detect branch for EdgeTPU)

* Update requirements.txt

* Replace torch.load() with attempt_load()

* Update requirements.txt

* Add --tf-raw-resize to set half_pixel_centers=False

* Add --agnostic-nms for TF class-agnostic NMS

* Cleanup after merge

* Cleanup2 after merge

* Cleanup3 after merge

* Add tf.py docstring with credit and usage

* pb saved_model and tflite use only one model in detect.py

* Add use cases in docstring of tf.py

* Remove redundant `stride` definition

* Remove keras direct import

* Fix `check_requirements(('tensorflow>=2.4.1',))`

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

detect.py

@@ -12,6 +12,7 @@ import time
 from pathlib import Path
 
 import cv2
+import numpy as np
 import torch
 import torch.backends.cudnn as cudnn
 
@@ -51,6 +52,7 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
         hide_labels=False,  # hide labels
         hide_conf=False,  # hide confidences
         half=False,  # use FP16 half-precision inference
+        tfl_int8=False,  # INT8 quantized TFLite model
         ):
     save_img = not nosave and not source.endswith('.txt')  # save inference images
     webcam = source.isnumeric() or source.endswith('.txt') or source.lower().startswith(
@@ -68,7 +70,7 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
     # Load model
     w = weights[0] if isinstance(weights, list) else weights
     classify, suffix = False, Path(w).suffix.lower()
-    pt, onnx, tflite, pb, graph_def = (suffix == x for x in ['.pt', '.onnx', '.tflite', '.pb', ''])  # backend
+    pt, onnx, tflite, pb, saved_model = (suffix == x for x in ['.pt', '.onnx', '.tflite', '.pb', ''])  # backend
     stride, names = 64, [f'class{i}' for i in range(1000)]  # assign defaults
     if pt:
         model = attempt_load(weights, map_location=device)  # load FP32 model
@@ -83,30 +85,49 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
         check_requirements(('onnx', 'onnxruntime'))
         import onnxruntime
         session = onnxruntime.InferenceSession(w, None)
+    else:  # TensorFlow models
+        check_requirements(('tensorflow>=2.4.1',))
+        import tensorflow as tf
+        if pb:  # https://www.tensorflow.org/guide/migrate#a_graphpb_or_graphpbtxt
+            def wrap_frozen_graph(gd, inputs, outputs):
+                x = tf.compat.v1.wrap_function(lambda: tf.compat.v1.import_graph_def(gd, name=""), [])  # wrapped import
+                return x.prune(tf.nest.map_structure(x.graph.as_graph_element, inputs),
+                               tf.nest.map_structure(x.graph.as_graph_element, outputs))
+
+            graph_def = tf.Graph().as_graph_def()
+            graph_def.ParseFromString(open(w, 'rb').read())
+            frozen_func = wrap_frozen_graph(gd=graph_def, inputs="x:0", outputs="Identity:0")
+        elif saved_model:
+            model = tf.keras.models.load_model(w)
+        elif tflite:
+            interpreter = tf.lite.Interpreter(model_path=w)  # load TFLite model
+            interpreter.allocate_tensors()  # allocate
+            input_details = interpreter.get_input_details()  # inputs
+            output_details = interpreter.get_output_details()  # outputs
     imgsz = check_img_size(imgsz, s=stride)  # check image size
 
     # Dataloader
     if webcam:
         view_img = check_imshow()
         cudnn.benchmark = True  # set True to speed up constant image size inference
-        dataset = LoadStreams(source, img_size=imgsz, stride=stride)
+        dataset = LoadStreams(source, img_size=imgsz, stride=stride, auto=pt)
         bs = len(dataset)  # batch_size
     else:
-        dataset = LoadImages(source, img_size=imgsz, stride=stride)
+        dataset = LoadImages(source, img_size=imgsz, stride=stride, auto=pt)
         bs = 1  # batch_size
     vid_path, vid_writer = [None] * bs, [None] * bs
 
     # Run inference
     if pt and device.type != 'cpu':
-        model(torch.zeros(1, 3, imgsz, imgsz).to(device).type_as(next(model.parameters())))  # run once
+        model(torch.zeros(1, 3, *imgsz).to(device).type_as(next(model.parameters())))  # run once
     t0 = time.time()
     for path, img, im0s, vid_cap in dataset:
-        if pt:
+        if onnx:
+            img = img.astype('float32')
+        else:
             img = torch.from_numpy(img).to(device)
             img = img.half() if half else img.float()  # uint8 to fp16/32
-        elif onnx:
-            img = img.astype('float32')
-        img /= 255.0  # 0 - 255 to 0.0 - 1.0
+        img = img / 255.0  # 0 - 255 to 0.0 - 1.0
         if len(img.shape) == 3:
             img = img[None]  # expand for batch dim
 
@@ -117,6 +138,27 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
             pred = model(img, augment=augment, visualize=visualize)[0]
         elif onnx:
             pred = torch.tensor(session.run([session.get_outputs()[0].name], {session.get_inputs()[0].name: img}))
+        else:  # tensorflow model (tflite, pb, saved_model)
+            imn = img.permute(0, 2, 3, 1).cpu().numpy()  # image in numpy
+            if pb:
+                pred = frozen_func(x=tf.constant(imn)).numpy()
+            elif saved_model:
+                pred = model(imn, training=False).numpy()
+            elif tflite:
+                if tfl_int8:
+                    scale, zero_point = input_details[0]['quantization']
+                    imn = (imn / scale + zero_point).astype(np.uint8)
+                interpreter.set_tensor(input_details[0]['index'], imn)
+                interpreter.invoke()
+                pred = interpreter.get_tensor(output_details[0]['index'])
+                if tfl_int8:
+                    scale, zero_point = output_details[0]['quantization']
+                    pred = (pred.astype(np.float32) - zero_point) * scale
+            pred[..., 0] *= imgsz[1]  # x
+            pred[..., 1] *= imgsz[0]  # y
+            pred[..., 2] *= imgsz[1]  # w
+            pred[..., 3] *= imgsz[0]  # h
+            pred = torch.tensor(pred)
 
         # NMS
         pred = non_max_suppression(pred, conf_thres, iou_thres, classes, agnostic_nms, max_det=max_det)
@@ -202,9 +244,9 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
 
 def parse_opt():
     parser = argparse.ArgumentParser()
-    parser.add_argument('--weights', nargs='+', type=str, default='yolov5s.pt', help='model.pt path(s)')
+    parser.add_argument('--weights', nargs='+', type=str, default='yolov5s.pb', help='model.pt path(s)')
     parser.add_argument('--source', type=str, default='data/images', help='file/dir/URL/glob, 0 for webcam')
-    parser.add_argument('--imgsz', '--img', '--img-size', type=int, default=640, help='inference size (pixels)')
+    parser.add_argument('--imgsz', '--img', '--img-size', nargs='+', type=int, default=[640], help='inference size h,w')
     parser.add_argument('--conf-thres', type=float, default=0.25, help='confidence threshold')
     parser.add_argument('--iou-thres', type=float, default=0.45, help='NMS IoU threshold')
     parser.add_argument('--max-det', type=int, default=1000, help='maximum detections per image')
@@ -226,7 +268,9 @@ def parse_opt():
     parser.add_argument('--hide-labels', default=False, action='store_true', help='hide labels')
     parser.add_argument('--hide-conf', default=False, action='store_true', help='hide confidences')
     parser.add_argument('--half', action='store_true', help='use FP16 half-precision inference')
+    parser.add_argument('--tfl-int8', action='store_true', help='INT8 quantized TFLite model')
     opt = parser.parse_args()
+    opt.imgsz *= 2 if len(opt.imgsz) == 1 else 1  # expand
     return opt