画Bounding box的几种方法

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在做深度学习的图像的localization时，需要画出bounding box和他们的类别名称，这里介绍两种方式

  1. 利用PIL中的ImageDraw.rectangle
  2. 利用matplotlib.patches
  3. 利用openCV

利用PIL中的ImageDraw.rectangle

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from PIL import Image, ImageDraw
import numpy as np

def draw_bbox(img, boxes, label, classes):
	'''
	Args:
	  img: PIL image
	  boxes: Nx4 
	  label: [c1, c2 ,c3,....] 1xN
	  classes: ['bird', 'cat', 'dog', ....]
	'''
    font = ImageFont.truetype("arial.ttf", 24)
    draw = ImageDraw.Draw(img)
    for i, box in enumerate(boxes):
        draw.rectangle(list(box), outline='red')
        draw.text((box[0],box[1]), classes[label[i]-1], font=font)
    img.show()

    
img = Image.open('12.jpg')
label = [1,2]
classes = ['sasiki', 'naruto']
boxes = np.array([[304,70,514,386],[547,55,762,360]], dtype=float)
draw_bbox(img, boxes, label, classes)

Imgur

利用matplotlib.patches

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import matplotlib.pyplot as plt
import cv2
import numpy as np

def draw_bbox(img, boxes, label=None, classes=None):
    '''
    Args:
      img: narrary image
      boxes: Nx4 [[xmin, ymin, xmax, ymax],[.. ..]]
      label: [c1, c2 ,c3,....] 1xN
      classes: ['bird', 'cat', 'dog', ....]
    '''
    plt.imshow(img)
    wh = boxes[:,2:4] - boxes[:,0:2]
    for i in range(len(boxes)):
        currentAxis=plt.gca()
        rect=patches.Rectangle((boxes[i,0], boxes[i,1]),wh[i, 0],wh[i, 1],linewidth=1,edgecolor='r',facecolor='none')
        currentAxis.add_patch(rect)
        plt.text(boxes[i,0], boxes[i,1], classes[label[i]-1], color='white',fontsize=16)
    plt.show()
    
    
img = cv2.imread('12.jpg')
boxes = np.array([[304,70,514,386],[547,55,762,360]], dtype=float)
label = [1, 2]
classes = ['sasiki', 'naruto']
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
draw_bbox(img, boxes, label, classes)

Imgur

利用openCV

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import cv2
import numpy as np
from PIL import Image, ImageDraw

def draw_bbox(img, boxes, label, classes):
    for i in range(len(boxes)):
        pt1 = (int(boxes[i,0]),int(boxes[i,1]))
        pt2 = (int(boxes[i,2]),int(boxes[i,3]))
        cv2.rectangle(img, pt1, pt2, (0,255,0), 4)

        font = cv2.FONT_HERSHEY_SIMPLEX
        cv2.putText(img, classes[label[i]-1], pt1, font, 2, (255,0,0), 6)

    # using Image to show
    img_new = Image.fromarray(img)
    img_new.show()
    # using matplotlib.pyplot
    plt.imshow(img)
    plt.show()
    
    
img = cv2.imread('12.jpg')
boxes = np.array([[304,70,514,386],[547,55,762,360]], dtype=float)
label = [1, 2]
classes = ['sasiki', 'naruto']

img = BGR2RGB(img)
draw_bbox(img, boxes, label, classes)

Imgur