opencv/samples/dnn/object_detection.py

import cv2 as cv
import argparse
import numpy as np
import sys
import time
from threading import Thread
if sys.version_info[0] == 2:
    import Queue as queue
else:
    import queue

from common import *
from tf_text_graph_common import readTextMessage
from tf_text_graph_ssd import createSSDGraph
from tf_text_graph_faster_rcnn import createFasterRCNNGraph

backends = (cv.dnn.DNN_BACKEND_DEFAULT, cv.dnn.DNN_BACKEND_HALIDE, cv.dnn.DNN_BACKEND_INFERENCE_ENGINE, cv.dnn.DNN_BACKEND_OPENCV,
            cv.dnn.DNN_BACKEND_VKCOM, cv.dnn.DNN_BACKEND_CUDA)
targets = (cv.dnn.DNN_TARGET_CPU, cv.dnn.DNN_TARGET_OPENCL, cv.dnn.DNN_TARGET_OPENCL_FP16, cv.dnn.DNN_TARGET_MYRIAD, cv.dnn.DNN_TARGET_HDDL,
           cv.dnn.DNN_TARGET_VULKAN, cv.dnn.DNN_TARGET_CUDA, cv.dnn.DNN_TARGET_CUDA_FP16)

parser = argparse.ArgumentParser(add_help=False)
parser.add_argument('--zoo', default=os.path.join(os.path.dirname(os.path.abspath(__file__)), 'models.yml'),
                    help='An optional path to file with preprocessing parameters.')
parser.add_argument('--input', help='Path to input image or video file. Skip this argument to capture frames from a camera.')
parser.add_argument('--out_tf_graph', default='graph.pbtxt',
                    help='For models from TensorFlow Object Detection API, you may '
                         'pass a .config file which was used for training through --config '
                         'argument. This way an additional .pbtxt file with TensorFlow graph will be created.')
parser.add_argument('--framework', choices=['caffe', 'tensorflow', 'torch', 'darknet', 'dldt'],
                    help='Optional name of an origin framework of the model. '
                         'Detect it automatically if it does not set.')
parser.add_argument('--thr', type=float, default=0.5, help='Confidence threshold')
parser.add_argument('--nms', type=float, default=0.4, help='Non-maximum suppression threshold')
parser.add_argument('--backend', choices=backends, default=cv.dnn.DNN_BACKEND_DEFAULT, type=int,
                    help="Choose one of computation backends: "
                         "%d: automatically (by default), "
                         "%d: Halide language (http://halide-lang.org/), "
                         "%d: Intel's Deep Learning Inference Engine (https://software.intel.com/openvino-toolkit), "
                         "%d: OpenCV implementation, "
                         "%d: VKCOM, "
                         "%d: CUDA" % backends)
parser.add_argument('--target', choices=targets, default=cv.dnn.DNN_TARGET_CPU, type=int,
                    help='Choose one of target computation devices: '
                         '%d: CPU target (by default), '
                         '%d: OpenCL, '
                         '%d: OpenCL fp16 (half-float precision), '
                         '%d: NCS2 VPU, '
                         '%d: HDDL VPU, '
                         '%d: Vulkan, '
                         '%d: CUDA, '
                         '%d: CUDA fp16 (half-float preprocess)' % targets)
parser.add_argument('--async', type=int, default=0,
                    dest='asyncN',
                    help='Number of asynchronous forwards at the same time. '
                         'Choose 0 for synchronous mode')
args, _ = parser.parse_known_args()
add_preproc_args(args.zoo, parser, 'object_detection')
parser = argparse.ArgumentParser(parents=[parser],
                                 description='Use this script to run object detection deep learning networks using OpenCV.',
                                 formatter_class=argparse.ArgumentDefaultsHelpFormatter)
args = parser.parse_args()

args.model = findFile(args.model)
args.config = findFile(args.config)
args.classes = findFile(args.classes)

# If config specified, try to load it as TensorFlow Object Detection API's pipeline.
config = readTextMessage(args.config)
if 'model' in config:
    print('TensorFlow Object Detection API config detected')
    if 'ssd' in config['model'][0]:
        print('Preparing text graph representation for SSD model: ' + args.out_tf_graph)
        createSSDGraph(args.model, args.config, args.out_tf_graph)
        args.config = args.out_tf_graph
    elif 'faster_rcnn' in config['model'][0]:
        print('Preparing text graph representation for Faster-RCNN model: ' + args.out_tf_graph)
        createFasterRCNNGraph(args.model, args.config, args.out_tf_graph)
        args.config = args.out_tf_graph


# Load names of classes
classes = None
if args.classes:
    with open(args.classes, 'rt') as f:
        classes = f.read().rstrip('\n').split('\n')

# Load a network
net = cv.dnn.readNet(cv.samples.findFile(args.model), cv.samples.findFile(args.config), args.framework)
net.setPreferableBackend(args.backend)
net.setPreferableTarget(args.target)
outNames = net.getUnconnectedOutLayersNames()

confThreshold = args.thr
nmsThreshold = args.nms

def postprocess(frame, outs):
    frameHeight = frame.shape[0]
    frameWidth = frame.shape[1]

    def drawPred(classId, conf, left, top, right, bottom):
        # Draw a bounding box.
        cv.rectangle(frame, (left, top), (right, bottom), (0, 255, 0))

        label = '%.2f' % conf

        # Print a label of class.
        if classes:
            assert(classId < len(classes))
            label = '%s: %s' % (classes[classId], label)

        labelSize, baseLine = cv.getTextSize(label, cv.FONT_HERSHEY_SIMPLEX, 0.5, 1)
        top = max(top, labelSize[1])
        cv.rectangle(frame, (left, top - labelSize[1]), (left + labelSize[0], top + baseLine), (255, 255, 255), cv.FILLED)
        cv.putText(frame, label, (left, top), cv.FONT_HERSHEY_SIMPLEX, 0.5, (0, 0, 0))

    layerNames = net.getLayerNames()
    lastLayerId = net.getLayerId(layerNames[-1])
    lastLayer = net.getLayer(lastLayerId)

    classIds = []
    confidences = []
    boxes = []
    if lastLayer.type == 'DetectionOutput':
        # Network produces output blob with a shape 1x1xNx7 where N is a number of
        # detections and an every detection is a vector of values
        # [batchId, classId, confidence, left, top, right, bottom]
        for out in outs:
            for detection in out[0, 0]:
                confidence = detection[2]
                if confidence > confThreshold:
                    left = int(detection[3])
                    top = int(detection[4])
                    right = int(detection[5])
                    bottom = int(detection[6])
                    width = right - left + 1
                    height = bottom - top + 1
                    if width <= 2 or height <= 2:
                        left = int(detection[3] * frameWidth)
                        top = int(detection[4] * frameHeight)
                        right = int(detection[5] * frameWidth)
                        bottom = int(detection[6] * frameHeight)
                        width = right - left + 1
                        height = bottom - top + 1
                    classIds.append(int(detection[1]) - 1)  # Skip background label
                    confidences.append(float(confidence))
                    boxes.append([left, top, width, height])
    elif lastLayer.type == 'Region':
        # Network produces output blob with a shape NxC where N is a number of
        # detected objects and C is a number of classes + 4 where the first 4
        # numbers are [center_x, center_y, width, height]
        for out in outs:
            for detection in out:
                scores = detection[5:]
                classId = np.argmax(scores)
                confidence = scores[classId]
                if confidence > confThreshold:
                    center_x = int(detection[0] * frameWidth)
                    center_y = int(detection[1] * frameHeight)
                    width = int(detection[2] * frameWidth)
                    height = int(detection[3] * frameHeight)
                    left = int(center_x - width / 2)
                    top = int(center_y - height / 2)
                    classIds.append(classId)
                    confidences.append(float(confidence))
                    boxes.append([left, top, width, height])
    else:
        print('Unknown output layer type: ' + lastLayer.type)
        exit()

    # NMS is used inside Region layer only on DNN_BACKEND_OPENCV for another backends we need NMS in sample
    # or NMS is required if number of outputs > 1
    if len(outNames) > 1 or lastLayer.type == 'Region' and args.backend != cv.dnn.DNN_BACKEND_OPENCV:
        indices = []
        classIds = np.array(classIds)
        boxes = np.array(boxes)
        confidences = np.array(confidences)
        unique_classes = set(classIds)
        for cl in unique_classes:
            class_indices = np.where(classIds == cl)[0]
            conf = confidences[class_indices]
            box  = boxes[class_indices].tolist()
            nms_indices = cv.dnn.NMSBoxes(box, conf, confThreshold, nmsThreshold)
            nms_indices = nms_indices[:, 0] if len(nms_indices) else []
            indices.extend(class_indices[nms_indices])
    else:
        indices = np.arange(0, len(classIds))

    for i in indices:
        box = boxes[i]
        left = box[0]
        top = box[1]
        width = box[2]
        height = box[3]
        drawPred(classIds[i], confidences[i], left, top, left + width, top + height)

# Process inputs
winName = 'Deep learning object detection in OpenCV'
cv.namedWindow(winName, cv.WINDOW_NORMAL)

def callback(pos):
    global confThreshold
    confThreshold = pos / 100.0

cv.createTrackbar('Confidence threshold, %', winName, int(confThreshold * 100), 99, callback)

cap = cv.VideoCapture(cv.samples.findFileOrKeep(args.input) if args.input else 0)

class QueueFPS(queue.Queue):
    def __init__(self):
        queue.Queue.__init__(self)
        self.startTime = 0
        self.counter = 0

    def put(self, v):
        queue.Queue.put(self, v)
        self.counter += 1
        if self.counter == 1:
            self.startTime = time.time()

    def getFPS(self):
        return self.counter / (time.time() - self.startTime)


process = True

#
# Frames capturing thread
#
framesQueue = QueueFPS()
def framesThreadBody():
    global framesQueue, process

    while process:
        hasFrame, frame = cap.read()
        if not hasFrame:
            break
        framesQueue.put(frame)


#
# Frames processing thread
#
processedFramesQueue = queue.Queue()
predictionsQueue = QueueFPS()
def processingThreadBody():
    global processedFramesQueue, predictionsQueue, args, process

    futureOutputs = []
    while process:
        # Get a next frame
        frame = None
        try:
            frame = framesQueue.get_nowait()

            if args.asyncN:
                if len(futureOutputs) == args.asyncN:
                    frame = None  # Skip the frame
            else:
                framesQueue.queue.clear()  # Skip the rest of frames
        except queue.Empty:
            pass


        if not frame is None:
            frameHeight = frame.shape[0]
            frameWidth = frame.shape[1]

            # Create a 4D blob from a frame.
            inpWidth = args.width if args.width else frameWidth
            inpHeight = args.height if args.height else frameHeight
            blob = cv.dnn.blobFromImage(frame, size=(inpWidth, inpHeight), swapRB=args.rgb, ddepth=cv.CV_8U)
            processedFramesQueue.put(frame)

            # Run a model
            net.setInput(blob, scalefactor=args.scale, mean=args.mean)
            if net.getLayer(0).outputNameToIndex('im_info') != -1:  # Faster-RCNN or R-FCN
                frame = cv.resize(frame, (inpWidth, inpHeight))
                net.setInput(np.array([[inpHeight, inpWidth, 1.6]], dtype=np.float32), 'im_info')

            if args.asyncN:
                futureOutputs.append(net.forwardAsync())
            else:
                outs = net.forward(outNames)
                predictionsQueue.put(np.copy(outs))

        while futureOutputs and futureOutputs[0].wait_for(0):
            out = futureOutputs[0].get()
            predictionsQueue.put(np.copy([out]))

            del futureOutputs[0]


framesThread = Thread(target=framesThreadBody)
framesThread.start()

processingThread = Thread(target=processingThreadBody)
processingThread.start()

#
# Postprocessing and rendering loop
#
while cv.waitKey(1) < 0:
    try:
        # Request prediction first because they put after frames
        outs = predictionsQueue.get_nowait()
        frame = processedFramesQueue.get_nowait()

        postprocess(frame, outs)

        # Put efficiency information.
        if predictionsQueue.counter > 1:
            label = 'Camera: %.2f FPS' % (framesQueue.getFPS())
            cv.putText(frame, label, (0, 15), cv.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0))

            label = 'Network: %.2f FPS' % (predictionsQueue.getFPS())
            cv.putText(frame, label, (0, 30), cv.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0))

            label = 'Skipped frames: %d' % (framesQueue.counter - predictionsQueue.counter)
            cv.putText(frame, label, (0, 45), cv.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0))

        cv.imshow(winName, frame)
    except queue.Empty:
        pass


process = False
framesThread.join()
processingThread.join()