用python解释fbuf2.pixel(y1, x1, fbuf.pixel(x1, (h - 1) - y1))
时间: 2023-10-31 14:04:10 浏览: 12
这段代码中,假设fbuf和fbuf2都是图像处理中的类,有pixel方法用于获取像素点的颜色值。x1和y1代表像素点的横纵坐标,h代表图像的高度。该代码的作用是获取fbuf中坐标为(x1, (h-1)-y1)的像素点的颜色值,并将其作为第三个参数传递给fbuf2的pixel方法,获取fbuf2中坐标为(y1, x1)的像素点的颜色值。这样处理后,就可以将fbuf中的图像“旋转90度”并保存到fbuf2中,实现图像的旋转操作。
相关问题
不使用cv.HoughLines与cv.HoughLinesP实现Hough直线检测的Python代码
以下是一个实现Hough直线检测的Python代码,不使用cv.HoughLines和cv.HoughLinesP:
```
import numpy as np
import cv2
def hough_lines(image):
# Convert image to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# Apply Canny edge detection
edges = cv2.Canny(gray, 50, 150)
# Define the Hough transform parameters
rho = 1
theta = np.pi/180
threshold = 50
# Initialize accumulator matrix
acc = np.zeros((edges.shape[0], edges.shape[1]))
# Loop over every pixel in the edges image
for x in range(edges.shape[0]):
for y in range(edges.shape[1]):
# Check if pixel is an edge
if edges[x,y] != 0:
# Loop over every possible theta value
for t in range(int(np.pi/theta)):
# Calculate rho for this theta value
r = int(x*np.cos(t*theta) + y*np.sin(t*theta))
# Increment accumulator cell
acc[r,t] += 1
# Find the indices of the cells with the highest values in the accumulator matrix
indices = np.argwhere(acc > threshold)
# Initialize list to hold lines
lines = []
# Loop over the indices and convert rho and theta back to x,y coordinates
for i in range(len(indices)):
r = indices[i][0]
t = indices[i][1]
a = np.cos(t*theta)
b = np.sin(t*theta)
x0 = a*r
y0 = b*r
x1 = int(x0 + 1000*(-b))
y1 = int(y0 + 1000*(a))
x2 = int(x0 - 1000*(-b))
y2 = int(y0 - 1000*(a))
lines.append((x1,y1,x2,y2))
return lines
# Test the function on an image
image = cv2.imread('test_image.jpg')
lines = hough_lines(image)
# Draw the lines on the image
for line in lines:
x1,y1,x2,y2 = line
cv2.line(image, (x1,y1), (x2,y2), (0,255,0), 2)
# Display the image
cv2.imshow('Hough Lines', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
```
该代码的实现过程与cv.HoughLinesP类似,但是没有使用OpenCV的函数,而是手动实现了Hough变换和线段检测。
class SpiralIterator: def init(self, source, x=810, y=500, length=None): self.source = source self.row = np.shape(self.source)[0]#第一个元素是行数 self.col = np.shape(self.source)[1]#第二个元素是列数 if length: self.length = min(length, np.size(self.source)) else: self.length = np.size(self.source) if x: self.x = x else: self.x = self.row // 2 if y: self.y = y else: self.y = self.col // 2 self.i = self.x self.j = self.y self.iteSize = 0 geo_transform = dsm_data.GetGeoTransform() self.x_origin = geo_transform[0] self.y_origin = geo_transform[3] self.pixel_width = geo_transform[1] self.pixel_height = geo_transform[5] def hasNext(self): return self.iteSize < self.length # 不能取更多值了 def get(self): if self.hasNext(): # 还能再取一个值 # 先记录当前坐标的值 —— 准备返回 i = self.i j = self.j val = self.source[i][j] # 计算下一个值的坐标 relI = self.i - self.x # 相对坐标 relJ = self.j - self.y # 相对坐标 if relJ > 0 and abs(relI) < relJ: self.i -= 1 # 上 elif relI < 0 and relJ > relI: self.j -= 1 # 左 elif relJ < 0 and abs(relJ) > relI: self.i += 1 # 下 elif relI >= 0 and relI >= relJ: self.j += 1 # 右 #判断索引是否在矩阵内 x = self.x_origin + (j + 0.5) * self.pixel_width y = self.y_origin + (i + 0.5) * self.pixel_height z = val self.iteSize += 1 return x, y, z dsm_path = 'C:\sanwei\jianmo\Productions\Production_2\Production_2_DSM_part_2_2.tif' dsm_data = gdal.Open(dsm_path) dsm_array = dsm_data.ReadAsArray() spiral_iterator = SpiralIterator(dsm_array,x=810,y=500) while spiral_iterator.hasNext(): x, y, z = spiral_iterator.get() print(f'Value at ({x},{y}):{z}')这段代码如何添加共线方程
共线方程是用于判断三个点是否共线的方程,可以使用向量叉积的方式表示。假设我们要判断三个点 $A(x_1,y_1,z_1)$,$B(x_2,y_2,z_2)$,$C(x_3,y_3,z_3)$ 是否共线,可以使用以下公式:
$$(\vec{AB} \times \vec{AC}) \cdot \vec{n} = 0$$
其中,$\vec{AB}$ 和 $\vec{AC}$ 分别表示从 $A$ 到 $B$,从 $A$ 到 $C$ 的向量,$\vec{n}$ 表示法向量,可以任意选择一组垂直于 $\vec{AB}$ 的向量。
在代码中,我们可以将获取的三个点坐标分别赋值给 $A(x_1,y_1,z_1)$,$B(x_2,y_2,z_2)$,$C(x_3,y_3,z_3)$,然后使用 numpy 库的 cross() 函数计算向量叉积,再将结果与 $\vec{n}$ 做点积,判断是否为零即可。
以下是修改后的代码:
```python
class SpiralIterator:
def __init__(self, source, x=810, y=500, length=None):
self.source = source
self.row = np.shape(self.source)[0]#第一个元素是行数
self.col = np.shape(self.source)[1]#第二个元素是列数
if length:
self.length = min(length, np.size(self.source))
else:
self.length = np.size(self.source)
if x:
self.x = x
else:
self.x = self.row // 2
if y:
self.y = y
else:
self.y = self.col // 2
self.i = self.x
self.j = self.y
self.iteSize = 0
geo_transform = dsm_data.GetGeoTransform()
self.x_origin = geo_transform[0]
self.y_origin = geo_transform[3]
self.pixel_width = geo_transform[1]
self.pixel_height = geo_transform[5]
def hasNext(self):
return self.iteSize < self.length # 不能取更多值了
def get(self):
if self.hasNext(): # 还能再取一个值
# 先记录当前坐标的值 —— 准备返回
i = self.i
j = self.j
val = self.source[i][j]
# 计算下一个值的坐标
relI = self.i - self.x # 相对坐标
relJ = self.j - self.y # 相对坐标
if relJ > 0 and abs(relI) < relJ:
self.i -= 1 # 上
elif relI < 0 and relJ > relI:
self.j -= 1 # 左
elif relJ < 0 and abs(relJ) > relI:
self.i += 1 # 下
elif relI >= 0 and relI >= relJ:
self.j += 1 # 右
# 判断索引是否在矩阵内
x = self.x_origin + (j + 0.5) * self.pixel_width
y = self.y_origin + (i + 0.5) * self.pixel_height
z = val
self.iteSize += 1
# 判断前三个点是否共线
if self.iteSize == 3:
A = np.array([self.x0, self.y0, self.z0])
B = np.array([self.x1, self.y1, self.z1])
C = np.array([x, y, z])
AB = B - A
AC = C - A
n = np.array([AB[1]*AC[2]-AB[2]*AC[1], AB[2]*AC[0]-AB[0]*AC[2], AB[0]*AC[1]-AB[1]*AC[0]])
if np.dot(n, n) == 0:
print("Three points are collinear!")
# 更新前两个点的坐标和值
self.x0 = self.x1
self.y0 = self.y1
self.z0 = self.z1
self.x1 = x
self.y1 = y
self.z1 = z
return x, y, z
dsm_path = 'C:\sanwei\jianmo\Productions\Production_2\Production_2_DSM_part_2_2.tif'
dsm_data = gdal.Open(dsm_path)
dsm_array = dsm_data.ReadAsArray()
spiral_iterator = SpiralIterator(dsm_array,x=810,y=500)
while spiral_iterator.hasNext():
x, y, z = spiral_iterator.get()
print(f'Value at ({x},{y}):{z}')
```
在 get() 函数中加入了判断前三个点是否共线的代码。其中,self.x0、self.y0、self.z0 表示第一个点的坐标和值,self.x1、self.y1、self.z1 表示第二个点的坐标和值,x、y、z 表示第三个点的坐标和值。
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