从函数传递和接收图像

Question

我正在创建一个函数（在 Python 中）expects/receives 多张人脸 [=18] 的单个图像 =]，以及 returns 多个较小的图像 （每个人脸一张图像）。我可以在函数内部执行 cv2.imshow 并看到预期的较小图像，但是当我尝试从函数外部执行 cv2.imshow 时，它不起作用（无法看到较小的图像，并得到一个 TypeError 代替）。希望得到一些指导。

def stills(user_image): #sub_frames = [] fqp_image_src = (user_image) raw_pic = cv2.imread(fqp_image_src) mpic = cv2.resize(raw_pic,(0,0), fx=0.30, fy=0.30) mpic_rgb = cv2.cvtColor(mpic, cv2.COLOR_BGR2RGB) face_boxes = haar_cascade_face.detectMultiScale(mpic_rgb, scaleFactor = 1.2, minNeighbors = 5) count = int(len(face_boxes)) for i in range(count): face_box = face_boxes[i] final = cv2.rectangle(mpic, (face_box[0], face_box[1]), ((face_box[0]+face_box[2]),(face_box[1]+face_box[3])), (0,255,0),2) sub_frame = final[face_box[1]:(face_box[1]+face_box[3]), face_box[0]:(face_box[0]+face_box[2])] #sub_frames.append(sub_frame) cv2.imshow('frame', sub_frame) # this works cv2.waitKey() return (sub_frame, final) # calling the function something = stills("abc.jpg") cv2.imshow('frame',something) # this does not work cv2.waitKey()

类型错误：参数 'mat'
应为 cv::UMat

Answer 1

这将达到您的预期，只是进行了一些简化并提供了完整的文件路径 . 一个关键错误是给 detectMultiScale 一张彩色图像，输入应该有 1 维，带有亮度（灰度）。

为了在方框中显示带有人脸的彩色图像，需要将图像的副本转换为 gar 比例并进行检测，给出坐标以在彩色图像中绘制。

import cv2
import os

# Take as a global the dir in witch is this file
PATH = os.path.dirname(os.path.abspath(__file__))

haar_cascade_face = cv2.CascadeClassifier(os.path.join(PATH, 'haarcascade_frontalface_alt.xml'))


def stills(user_image):
    image = os.path.join(PATH, user_image)
    image = cv2.imread(image)
    image = cv2.resize(image, (0, 0), fx=0.30, fy=0.30)

    gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    face_boxes = haar_cascade_face.detectMultiScale(gray_image, scaleFactor=1.073, minNeighbors=8)

    final = image  # make the funtion alwais give a image
    sub_frames = []

    # Check if there are faces
    if len(face_boxes) > 0:
        for x, y, w, h in face_boxes:
            final = cv2.rectangle(image, (x, y), (x+w, y+h), (0, 255, 0), 2)

            sub_frame = image[y:y+h, x:x+w]
            sub_frames.append([x, y, x+w, y+h])

            cv2.imshow('sub_frame', sub_frame)
            # cv2.waitKey() # No need to wait the user
    else:
        print('No faces found')

    return (sub_frames, final)


if __name__ == '__main__':
    fragments, final = stills("abc.jpg")
    cv2.imshow('frame', final)
    cv2.waitKey()

从函数传递和接收图像

Passing and Receiving Images from Function

python

opencv3.0