使用opencv python在图像上绘制网格线答案

【问题标题】：Drawing grid lines across the image uisng opencv python使用opencv python在图像上绘制网格线
【发布时间】：2017-06-29 05:00:41
【问题描述】：

使用 OpenCV python，我想在打开相机时制作一个网格。你们能帮我一个逻辑或代码吗？请找到下面的图片链接以便更好地理解。

Camera switched on and pointed to a floor

Grid Lines are split across the whole image

【问题讨论】：

标签： python opencv

【解决方案1】：

这是我的问题的解决方案。好好利用吧。

import matplotlib.pyplot as plt
import matplotlib.ticker as plticker
try:
    from PIL import Image
except ImportError:
    import Image

# Open image file
image = Image.open('bird.jpg')
my_dpi=200.

# Set up figure
fig=plt.figure(figsize=(float(image.size[0])/my_dpi,float(image.size[1])/my_dpi),dpi=my_dpi)
ax=fig.add_subplot(111)

# Remove whitespace from around the image
fig.subplots_adjust(left=0,right=1,bottom=0,top=1)

# Set the gridding interval: here we use the major tick interval
myInterval=300.
loc = plticker.MultipleLocator(base=myInterval)
ax.xaxis.set_major_locator(loc)
ax.yaxis.set_major_locator(loc)

# Add the grid
ax.grid(which='major', axis='both', linestyle='-', color='g')

# Add the image
ax.imshow(image)

# Find number of gridsquares in x and y direction
nx=abs(int(float(ax.get_xlim()[1]-ax.get_xlim()[0])/float(myInterval)))
ny=abs(int(float(ax.get_ylim()[1]-ax.get_ylim()[0])/float(myInterval)))




# Save the figure
fig.savefig('birdgrid_without_Label.jpg')

【讨论】：

【解决方案2】：

def draw_grid(img, line_color=(0, 255, 0), thickness=1, type_=_cv2.LINE_AA, pxstep=50):
    '''(ndarray, 3-tuple, int, int) -> void
    draw gridlines on img
    line_color:
        BGR representation of colour
    thickness:
        line thickness
    type:
        8, 4 or cv2.LINE_AA
    pxstep:
        grid line frequency in pixels
    '''
    x = pxstep
    y = pxstep
    while x < img.shape[1]:
        _cv2.line(img, (x, 0), (x, img.shape[0]), color=line_color, lineType=type_, thickness=thickness)
        x += pxstep

    while y < img.shape[0]:
        _cv2.line(img, (0, y), (img.shape[1], y), color=line_color, lineType=type_, thickness=thickness)
        y += pxstep

【讨论】：

【解决方案3】：

您可以使用cv2.line() 函数在输入图像上画线。因此，根据您要在哪里画线，您的基本代码将如下所示：

img = cv2.imread(r"path\to\img")
cv2.line(img, (start_x, start_y), (end_x, end_y), (255, 0, 0), 1, 1)

要获取图像的尺寸，您可以使用img.shape，它将返回(height, width)。

例如，要通过中心绘制一条垂直线，您的代码如下所示：

cv2.line(img, (int(img.shape[1]/2), 0),(int(img.shape[1]/2), img.shape[0]), (255, 0, 0), 1, 1)

【讨论】：

【解决方案4】：

这是一个创建 m x n 网格的简单解决方案（尽可能均匀地分割）：

import cv2 as cv  # tested with version 4.5.3.56 (pip install opencv-python)
import numpy as np


def draw_grid(img, grid_shape, color=(0, 255, 0), thickness=1):
    h, w, _ = img.shape
    rows, cols = grid_shape
    dy, dx = h / rows, w / cols

    # draw vertical lines
    for x in np.linspace(start=dx, stop=w-dx, num=cols-1):
        x = int(round(x))
        cv.line(img, (x, 0), (x, h), color=color, thickness=thickness)

    # draw horizontal lines
    for y in np.linspace(start=dy, stop=h-dy, num=rows-1):
        y = int(round(y))
        cv.line(img, (0, y), (w, y), color=color, thickness=thickness)

    return img

这是一个在 CLI 中包装此函数的脚本： https://gist.github.com/mathandy/389ddbad48810d188bdc997c3a1dab0c

【讨论】：