在脸部周围绘制奇特的矩形 [英] Drawing fancy rectangle around face

问题描述

我正在使用以下代码检测面部并在面部上方绘制矩形.

I am using the following code to detect face and draw rectangle on top of the face.

while True:
    # get video frame
    ret, img = cap.read()

    input_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    img_h, img_w, _ = np.shape(input_img)

    detected = detector(input_img, 1)

    for i, d in enumerate(detected):
        x1, y1, x2, y2, w, h = d.left(), d.top(), d.right() + 1, d.bottom() + 1, d.width(), d.height()
        cv2.rectangle(img, (x1, y1), (x2, y2), (255, 0, 0), 2)

    cv2.imshow("result", img)
    key = cv2.waitKey(30)

    if key == 27:
        break

矩形看起来像这样:

但是我正试图得到一个与此类似的矩形:

However Im trying to get a rectangle similar to this:

有没有可以帮助我获得这种有效矩形的OpenCV或dlib函数?

Is there any OpenCV or dlib function that can help me get this sort of effective rectangle?

推荐答案

使用绘制弧.

要绘制的框架包括4个相似的部分(每个角一个)，每个部分都旋转(或镜像).

The frame you want to draw consists of 4 similar parts (one per corner), each rotated (or mirrored).

让我们看一下左上角:

如您所见，我们需要绘制2个线段(长度为d)和一条弧线(半径为r的四分之一圆).

As you can see, we need to draw 2 line segments (of length d) and an arc (a quarter of a circle of radius r).

比方说，左上角的坐标是(x1, y1).

Let's say the coordinates of the top-left corner are (x1, y1).

这意味着弧将在位置(x1 + r, y1 + r)处具有中心.

That means that the arc will have a center at position (x1 + r, y1 + r).

其中一行将从(x1 + r, y1)到(x1 + r + d, y1).

另一行将从(x1, y1 + r)到(x1, y1 + r + d).

其他情况也会发生类似的情况.

Similar situation will happen with the other corners.

示例代码:

import cv2
import numpy as np

# ============================================================================

def draw_border(img, pt1, pt2, color, thickness, r, d):
    x1,y1 = pt1
    x2,y2 = pt2

    # Top left
    cv2.line(img, (x1 + r, y1), (x1 + r + d, y1), color, thickness)
    cv2.line(img, (x1, y1 + r), (x1, y1 + r + d), color, thickness)
    cv2.ellipse(img, (x1 + r, y1 + r), (r, r), 180, 0, 90, color, thickness)

    # Top right
    cv2.line(img, (x2 - r, y1), (x2 - r - d, y1), color, thickness)
    cv2.line(img, (x2, y1 + r), (x2, y1 + r + d), color, thickness)
    cv2.ellipse(img, (x2 - r, y1 + r), (r, r), 270, 0, 90, color, thickness)

    # Bottom left
    cv2.line(img, (x1 + r, y2), (x1 + r + d, y2), color, thickness)
    cv2.line(img, (x1, y2 - r), (x1, y2 - r - d), color, thickness)
    cv2.ellipse(img, (x1 + r, y2 - r), (r, r), 90, 0, 90, color, thickness)

    # Bottom right
    cv2.line(img, (x2 - r, y2), (x2 - r - d, y2), color, thickness)
    cv2.line(img, (x2, y2 - r), (x2, y2 - r - d), color, thickness)
    cv2.ellipse(img, (x2 - r, y2 - r), (r, r), 0, 0, 90, color, thickness)

# ============================================================================

img = np.zeros((256,256,3), dtype=np.uint8)

draw_border(img, (10,10), (100, 100), (127,255,255), 1, 10, 20)
draw_border(img, (128,128), (240, 160), (255,255,127), 1, 5, 5)

cv2.imwrite('round_rect.png', img)

结果:

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