坐标列表摘要

Question

我需要分析坐标列表。程序应该“总结”列表。

from PIL import Image
im = Image.open('map.png')
rgb_im = im.convert('RGB')
l = []
x = 0
y = 0

for y in range(im.size[1]):
    for x in range(im.size[0]):
        if sum(rgb_im.getpixel((x, y))) == 0:     
            a = [x, y]
                l.append(a)

这会从一张图像中生成所有黑色像素的坐标列表，该图像在白色表面上有几个黑色矩形。输出是这样的：

[[599, 257], [600, 257], [601, 257], [602, 257], [603, 257], [604, 257], [605, 257], [606, 257], [599, 258], [600, 258], [601, 258], [602, 258], [603, 258], [604, 258], [605, 258], [606, 258], [599, 259], [600, 259], [601, 259], [602, 259], [603, 259], [604, 259], [605, 259], [606, 259], [599, 260], [600, 260], [601, 260], [602, 260], [603, 260], [604, 260], [605, 260], [606, 260], [599, 261], [600, 261], [601, 261], [602, 261], [603, 261], [604, 261], [605, 261], [606, 261], [599, 262], [600, 262], [601, 262], [602, 262], [603, 262], [604, 262], [605, 262], [606, 262], [599, 263], [600, 263], [601, 263], [602, 263], [603, 263], [604, 263], [605, 263], [606, 263], [622, 286], [623, 286], [624, 286], [625, 286], [626, 286], [627, 286], [622, 287], [623, 287], [624, 287], [625, 287], [626, 287], [627, 287], [622, 288], [623, 288], [624, 288], [625, 288], [626, 288], [627, 288], [622, 289], [623, 289], [624, 289], [625, 289], [626, 289], [627, 289], [622, 290], [623, 290], [624, 290], [625, 290], [626, 290], [627, 290], [622, 291], [623, 291], [624, 291], [625, 291], [626, 291], [627, 291]]

“摘要”应该是关于黑色矩形的信息。输出应该是：每个矩形的[x-coordinate, y-coordinate, length, height]，这需要原点的坐标。

在这种情况下：[[599, 257, 8, 7], [622, 287, 6, 6]]

我不知道我是否应该使用数组或矩阵或完全不同的东西。我对想法持开放态度。重要的部分是从这些图像中获取信息。

提前谢谢大家！

Answer 1

您可以使用floodfill、connected components，或者其他方法。

在这里，我们将利用我们知道我们正在寻找与x 和y 轴对齐的矩形形状。

该算法在 x 和 y 方向扫描每个给定像素的四个相邻像素，并确定它们是否是孤立的黑色矩形的一部分；如果是，则将像素添加到组件中；当没有找到新的像素属于某个组件时，下一个可用像素将用作下一个组件的种子，以此类推。

从孤立的单个组件（黑色矩形）中，很容易找到边界框，并根据需要进行表示。

import tkinter as tk


def find_extent(points):
    xmin = min(x for x, _ in points)
    xmax = max(x for x, _ in points)
    ymin = min(y for _, y in points)
    ymax = max(y for _, y in points)
    return(xmin, ymin, xmax, ymax)
    
def get_four_neighbors(point):
    x, y = point
    return (x, y+1), (x, y-1), (x+1, y), (x-1, y)
    
def isolate_components(points):
    """return connected components,
    taking advantage that we are looking for rectangles
    """
    components = []
    points_ = set(tuple(point) for point in points)
    while points_:
        current_comp_head = points_.pop()
        to_visit = [current_comp_head]
        component = []
        while to_visit:
            current = to_visit.pop()
            component.append(current)
            for point in get_four_neighbors(current):
                if point in points_:
                    to_visit.append(point)
                    points_.remove(point)
        components.append(component)
    return components
    
root = tk.Tk()
canvas = tk.Canvas(root, width=800, height=800)
canvas.pack(expand=True, fill=tk.BOTH)

points = [[599, 257], [600, 257], [601, 257], [602, 257], [603, 257], [604, 257], [605, 257], [606, 257], [599, 258], [600, 258], [601, 258], [602, 258], [603, 258], [604, 258], [605, 258], [606, 258], [599, 259], [600, 259], [601, 259], [602, 259], [603, 259], [604, 259], [605, 259], [606, 259], [599, 260], [600, 260], [601, 260], [602, 260], [603, 260], [604, 260], [605, 260], [606, 260], [599, 261], [600, 261], [601, 261], [602, 261], [603, 261], [604, 261], [605, 261], [606, 261], [599, 262], [600, 262], [601, 262], [602, 262], [603, 262], [604, 262], [605, 262], [606, 262], [599, 263], [600, 263], [601, 263], [602, 263], [603, 263], [604, 263], [605, 263], [606, 263], [622, 286], [623, 286], [624, 286], [625, 286], [626, 286], [627, 286], [622, 287], [623, 287], [624, 287], [625, 287], [626, 287], [627, 287], [622, 288], [623, 288], [624, 288], [625, 288], [626, 288], [627, 288], [622, 289], [623, 289], [624, 289], [625, 289], [626, 289], [627, 289], [622, 290], [623, 290], [624, 290], [625, 290], [626, 290], [627, 290], [622, 291], [623, 291], [624, 291], [625, 291], [626, 291], [627, 291]]

components = isolate_components(points)

summaries = []
for component in components:
    summaries.append(find_extent(component))
    for x, y in component:
        canvas.create_rectangle(x, y, x, y, outline='blue', fill='blue')
    
for summary in summaries:
    x0, y0, x1, y1 = summary
    print(f'{x0}, {y0}, {x1-x0+1}, {y1-y0+1}')
    canvas.create_rectangle(x0, y0, x1+1, y1+1, outline='green', width=2)
        

root.mainloop()

输出：

599, 257, 8, 7
622, 286, 6, 6

（画布的裁剪截图）