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nvidia--tensorrt/samples/python/introductory_parser_samples/onnx_resnet50.py
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Python

#
# SPDX-FileCopyrightText: Copyright (c) 1993-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import os
# This sample uses an ONNX ResNet50 Model to create a TensorRT Inference Engine
import random
import sys
import numpy as np
import tensorrt as trt
from PIL import Image
sys.path.insert(1, os.path.join(sys.path[0], os.path.pardir))
import common
class ModelData(object):
MODEL_PATH = "ResNet50.onnx"
INPUT_SHAPE = (3, 224, 224)
# We can convert TensorRT data types to numpy types with trt.nptype()
DTYPE = trt.float32
# You can set the logger severity higher to suppress messages (or lower to display more messages).
TRT_LOGGER = trt.Logger(trt.Logger.WARNING)
# The Onnx path is used for Onnx models.
def build_engine_onnx(model_file):
builder = trt.Builder(TRT_LOGGER)
network = builder.create_network(1 << int(trt.NetworkDefinitionCreationFlag.STRONGLY_TYPED))
config = builder.create_builder_config()
parser = trt.OnnxParser(network, TRT_LOGGER)
config.set_memory_pool_limit(trt.MemoryPoolType.WORKSPACE, common.GiB(1))
# Load the Onnx model and parse it in order to populate the TensorRT network.
with open(model_file, "rb") as model:
if not parser.parse(model.read()):
print("ERROR: Failed to parse the ONNX file.")
for error in range(parser.num_errors):
print(parser.get_error(error))
return None
engine_bytes = builder.build_serialized_network(network, config)
runtime = trt.Runtime(TRT_LOGGER)
return runtime.deserialize_cuda_engine(engine_bytes)
def load_normalized_test_case(test_image, pagelocked_buffer):
# Converts the input image to a CHW Numpy array
def normalize_image(image):
# Resize, antialias and transpose the image to CHW.
c, h, w = ModelData.INPUT_SHAPE
image_arr = (
np.asarray(image.resize((w, h), Image.LANCZOS))
.transpose([2, 0, 1])
.astype(trt.nptype(ModelData.DTYPE))
.ravel()
)
# This particular ResNet50 model requires some preprocessing, specifically, mean normalization.
return (image_arr / 255.0 - 0.45) / 0.225
# Normalize the image and copy to pagelocked memory.
np.copyto(pagelocked_buffer, normalize_image(Image.open(test_image)))
return test_image
def main():
# Set the data path to the directory that contains the trained models and test images for inference.
_, data_files = common.find_sample_data(
description="Runs a ResNet50 network with a TensorRT inference engine.",
subfolder="resnet50",
find_files=[
"binoculars.jpeg",
"reflex_camera.jpeg",
"tabby_tiger_cat.jpg",
ModelData.MODEL_PATH,
"class_labels.txt",
],
)
# Get test images, models and labels.
test_images = data_files[0:3]
onnx_model_file, labels_file = data_files[3:]
labels = open(labels_file, "r").read().split("\n")
# Build a TensorRT engine.
engine = build_engine_onnx(onnx_model_file)
# Inference is the same regardless of which parser is used to build the engine, since the model architecture is the same.
# Allocate buffers
inputs, outputs, bindings = common.allocate_buffers(engine)
# Contexts are used to perform inference.
context = engine.create_execution_context()
# Use context manager for proper stream lifecycle management
with common.CudaStreamContext() as stream:
# Load a normalized test case into the host input page-locked buffer.
test_image = random.choice(test_images)
test_case = load_normalized_test_case(test_image, inputs[0].host)
# Run the engine. The output will be a 1D tensor of length 1000, where each value represents the
# probability that the image corresponds to that label
trt_outputs = common.do_inference(
context,
engine=engine,
bindings=bindings,
inputs=inputs,
outputs=outputs,
stream=stream,
)
# We use the highest probability as our prediction. Its index corresponds to the predicted label.
pred = labels[np.argmax(trt_outputs[0])]
common.free_buffers(inputs, outputs)
if "_".join(pred.split()) in os.path.splitext(os.path.basename(test_case))[0]:
print("Correctly recognized " + test_case + " as " + pred)
else:
print("Incorrectly recognized " + test_case + " as " + pred)
if __name__ == "__main__":
main()