如何在opencv中合并一个RGBA和一个RGB图像
如何在opencv中合并一个RGBA和一个RGB图像
提问于 2022-01-04 12:11:52
我有两张照片。在一幅图像中，通过以A图像格式编辑通道RGBA，白色像素被设置为透明(或无色)。假设这个图像名是image_rgba.png，另一个图像是image.jpg。现在，我希望使用下面的python代码将image_rgba.png映像放在image.jpg的特定位置
import cv2
import numpy as np
import matplotlib.pyplot as plt
image = cv2.imread('image.jpg')
label = cv2.imread('image_rgba.png')
label = cv2.cvtColor(label, cv2.COLOR_BGR2RGBA)
new_image = image.copy()
new_image = cv2.cvtColor(new_image, cv2.COLOR_BGR2RGBA)
new_image[200:290, 300:384, :] = label当我写这个图像时，image_rgba.png的边缘是无色的，在输出图像中被设置为白色(以下图像中绿色框的白色边缘)。
我希望绿色框标签的白色边缘不显示，而是背景图像显示在该像素。我发现了similar问题，但它无助于解决我的问题。如果有人能帮我，我会很感激的。
回答 1
Stack Overflow用户
回答已采纳
发布于 2022-01-04 13:38:13
这是你怎么做的。我不是OpenCV专家，所以可能有更简单的方法。代码中的注释解释了它的功能。总的想法是：
- 从PNG
- 提取α通道，提取具有相同大小的
- α混合的背景片段，
- 将结果放回背景
import cv2
def alphaMerge(small_foreground, background, top, left):
"""
Puts a small BGRA picture in front of a larger BGR background.
:param small_foreground: The overlay image. Must have 4 channels.
:param background: The background. Must have 3 channels.
:param top: Y position where to put the overlay.
:param left: X position where to put the overlay.
:return: a copy of the background with the overlay added.
"""
result = background.copy()
# From everything I read so far, it seems we need the alpha channel separately
# so let's split the overlay image into its individual channels
fg_b, fg_g, fg_r, fg_a = cv2.split(small_foreground)
# Make the range 0...1 instead of 0...255
fg_a = fg_a / 255.0
# Multiply the RGB channels with the alpha channel
label_rgb = cv2.merge([fg_b * fg_a, fg_g * fg_a, fg_r * fg_a])
# Work on a part of the background only
height, width = small_foreground.shape[0], small_foreground.shape[1]
part_of_bg = result[top:top + height, left:left + width, :]
# Same procedure as before: split the individual channels
bg_b, bg_g, bg_r = cv2.split(part_of_bg)
# Merge them back with opposite of the alpha channel
part_of_bg = cv2.merge([bg_b * (1 - fg_a), bg_g * (1 - fg_a), bg_r * (1 - fg_a)])
# Add the label and the part of the background
cv2.add(label_rgb, part_of_bg, part_of_bg)
# Replace a part of the background
result[top:top + height, left:left + width, :] = part_of_bg
return result
background = cv2.imread('image.jpg')
# Read the image "unchanged" to get the alpha channel as well
label = cv2.imread('image_rgba.png', cv2.IMREAD_UNCHANGED)
result = alphaMerge(label, background, 100, 200)
cv2.imshow("result", result)
cv2.waitKey()我在以下背景下进行了测试：
这个前景是：
结果如Python代码所示：
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原文链接：
https://stackoverflow.com/questions/70578600
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