Compile YOLO-V2 and YOLO-V3 in DarkNet Models

Author: Siju Samuel

This article is an introductory tutorial to deploy darknet models with TVM. All the required models and libraries will be downloaded from the internet by the script. This script runs the YOLO-V2 and YOLO-V3 Model with the bounding boxes Darknet parsing have dependancy with CFFI and CV2 library Please install CFFI and CV2 before executing this script

pip install cffi opencv-python

# numpy and matplotlib
import numpy as np
import matplotlib.pyplot as plt
import sys

# tvm, relay
import tvm
from tvm import te
from tvm import relay
from ctypes import *
from tvm.contrib.download import download_testdata
from tvm.relay.testing.darknet import __darknetffi__
import tvm.relay.testing.yolo_detection
import tvm.relay.testing.darknet

Choose the model

Models are: ‘yolov2’, ‘yolov3’ or ‘yolov3-tiny’

# Model name
MODEL_NAME = "yolov3"

Download required files

Download cfg and weights file if first time.

CFG_NAME = MODEL_NAME + ".cfg"
WEIGHTS_NAME = MODEL_NAME + ".weights"
REPO_URL = "https://github.com/dmlc/web-data/blob/main/darknet/"
CFG_URL = REPO_URL + "cfg/" + CFG_NAME + "?raw=true"
WEIGHTS_URL = "https://pjreddie.com/media/files/" + WEIGHTS_NAME

cfg_path = download_testdata(CFG_URL, CFG_NAME, module="darknet")
weights_path = download_testdata(WEIGHTS_URL, WEIGHTS_NAME, module="darknet")

# Download and Load darknet library
if sys.platform in ["linux", "linux2"]:
    DARKNET_LIB = "libdarknet2.0.so"
    DARKNET_URL = REPO_URL + "lib/" + DARKNET_LIB + "?raw=true"
elif sys.platform == "darwin":
    DARKNET_LIB = "libdarknet_mac2.0.so"
    DARKNET_URL = REPO_URL + "lib_osx/" + DARKNET_LIB + "?raw=true"
else:
    err = "Darknet lib is not supported on {} platform".format(sys.platform)
    raise NotImplementedError(err)

lib_path = download_testdata(DARKNET_URL, DARKNET_LIB, module="darknet")

DARKNET_LIB = __darknetffi__.dlopen(lib_path)
net = DARKNET_LIB.load_network(cfg_path.encode("utf-8"), weights_path.encode("utf-8"), 0)
dtype = "float32"
batch_size = 1

data = np.empty([batch_size, net.c, net.h, net.w], dtype)
shape_dict = {"data": data.shape}
print("Converting darknet to relay functions...")
mod, params = relay.frontend.from_darknet(net, dtype=dtype, shape=data.shape)

Import the graph to Relay

compile the model

target = tvm.target.Target("llvm", host="llvm")
dev = tvm.cpu(0)
data = np.empty([batch_size, net.c, net.h, net.w], dtype)
shape = {"data": data.shape}
print("Compiling the model...")
with tvm.transform.PassContext(opt_level=3):
    lib = relay.build(mod, target=target, params=params)

[neth, netw] = shape["data"][2:]  # Current image shape is 608x608

Load a test image

test_image = "dog.jpg"
print("Loading the test image...")
img_url = REPO_URL + "data/" + test_image + "?raw=true"
img_path = download_testdata(img_url, test_image, "data")

data = tvm.relay.testing.darknet.load_image(img_path, netw, neth)

Execute on TVM Runtime

The process is no different from other examples.

from tvm.contrib import graph_executor

m = graph_executor.GraphModule(lib["default"](dev))

# set inputs
m.set_input("data", tvm.nd.array(data.astype(dtype)))
# execute
print("Running the test image...")

# detection
# thresholds
thresh = 0.5
nms_thresh = 0.45

m.run()
# get outputs
tvm_out = []
if MODEL_NAME == "yolov2":
    layer_out = {}
    layer_out["type"] = "Region"
    # Get the region layer attributes (n, out_c, out_h, out_w, classes, coords, background)
    layer_attr = m.get_output(2).numpy()
    layer_out["biases"] = m.get_output(1).numpy()
    out_shape = (layer_attr[0], layer_attr[1] // layer_attr[0], layer_attr[2], layer_attr[3])
    layer_out["output"] = m.get_output(0).numpy().reshape(out_shape)
    layer_out["classes"] = layer_attr[4]
    layer_out["coords"] = layer_attr[5]
    layer_out["background"] = layer_attr[6]
    tvm_out.append(layer_out)

elif MODEL_NAME == "yolov3":
    for i in range(3):
        layer_out = {}
        layer_out["type"] = "Yolo"
        # Get the yolo layer attributes (n, out_c, out_h, out_w, classes, total)
        layer_attr = m.get_output(i * 4 + 3).numpy()
        layer_out["biases"] = m.get_output(i * 4 + 2).numpy()
        layer_out["mask"] = m.get_output(i * 4 + 1).numpy()
        out_shape = (layer_attr[0], layer_attr[1] // layer_attr[0], layer_attr[2], layer_attr[3])
        layer_out["output"] = m.get_output(i * 4).numpy().reshape(out_shape)
        layer_out["classes"] = layer_attr[4]
        tvm_out.append(layer_out)

elif MODEL_NAME == "yolov3-tiny":
    for i in range(2):
        layer_out = {}
        layer_out["type"] = "Yolo"
        # Get the yolo layer attributes (n, out_c, out_h, out_w, classes, total)
        layer_attr = m.get_output(i * 4 + 3).numpy()
        layer_out["biases"] = m.get_output(i * 4 + 2).numpy()
        layer_out["mask"] = m.get_output(i * 4 + 1).numpy()
        out_shape = (layer_attr[0], layer_attr[1] // layer_attr[0], layer_attr[2], layer_attr[3])
        layer_out["output"] = m.get_output(i * 4).numpy().reshape(out_shape)
        layer_out["classes"] = layer_attr[4]
        tvm_out.append(layer_out)
        thresh = 0.560

# do the detection and bring up the bounding boxes
img = tvm.relay.testing.darknet.load_image_color(img_path)
_, im_h, im_w = img.shape
dets = tvm.relay.testing.yolo_detection.fill_network_boxes(
    (netw, neth), (im_w, im_h), thresh, 1, tvm_out
)
last_layer = net.layers[net.n - 1]
tvm.relay.testing.yolo_detection.do_nms_sort(dets, last_layer.classes, nms_thresh)

coco_name = "coco.names"
coco_url = REPO_URL + "data/" + coco_name + "?raw=true"
font_name = "arial.ttf"
font_url = REPO_URL + "data/" + font_name + "?raw=true"
coco_path = download_testdata(coco_url, coco_name, module="data")
font_path = download_testdata(font_url, font_name, module="data")

with open(coco_path) as f:
    content = f.readlines()

names = [x.strip() for x in content]

tvm.relay.testing.yolo_detection.show_detections(img, dets, thresh, names, last_layer.classes)
tvm.relay.testing.yolo_detection.draw_detections(
    font_path, img, dets, thresh, names, last_layer.classes
)
plt.imshow(img.transpose(1, 2, 0))
plt.show()