图像处理: 设计自定义透明度水印

JNingWei

发布于 2018-09-28 14:47:28

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发布于 2018-09-28 14:47:28

文章被收录于专栏：JNing的专栏JNing的专栏

效果图

未加水印前：

水印掩码：

透明度为 0.3 的水印图片：

透明度为 1.0 的水印图片：

实现代码

感觉我自己写的这段代码，效果比opencv官网上给出的例子效果要好，水印中不会夹带黑色噪点。

# coding=utf-8
import cv2
import numpy as np

bottom = cv2.imread('elegent.jpg')
mark = cv2.imread('mask.jpg')

# 加水印
def waterMark(src, mask, transparency):
    # 对掩码：转为float型 --> 乘上透明度 --> 地板整数 --> 回到uint8型
    mask = np.floor(mask.astype(np.float32) * transparency).astype(np.uint8)
    dst = cv2.add(src, mask)
    # 防止溢出像素值域
    dst = dst*(dst<=255) + 255*(dst>255)
    # 回到uint8型
    dst = dst.astype(np.uint8)
    return dst

b_rows, b_cols, b_channels = bottom.shape
m_rows, m_cols, m_channels = mark.shape
# 将图片右下角矩形块 替换为 加过水印的矩形块
bottom[b_rows-m_rows:b_rows, b_cols-m_cols:b_cols, ] = waterMark(bottom[b_rows-m_rows:b_rows, b_cols-m_cols:b_cols, ], mark, 0.3)

# 保存水印图片
cv2.imwrite('waterMark.jpg', bottom)

cv2.imshow('waterMark', bottom)
cv2.waitKey(3000)
cv2.destroyAllWindows()

对比

OpenCV官网上的类似例程：

具体代码：

# coding=utf-8
import cv2

img1 = cv2.imread('elegent.jpg')
img2 = cv2.imread('mask.jpg')

b_rows, b_cols, b_channels = img1.shape
m_rows, m_cols, m_channels = img2.shape

# I want to put logo on top-left corner, So I create a ROI
rows,cols,channels = img2.shape
roi = img1[b_rows-m_rows:b_rows, b_cols-m_cols:b_cols, ]
# Now create a mask of logo and create its inverse mask also
img2gray = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)
ret, mask = cv2.threshold(img2gray, 10, 255, cv2.THRESH_BINARY)
mask_inv = cv2.bitwise_not(mask)
# Now black-out the area of logo in ROI
img1_bg = cv2.bitwise_and(roi,roi,mask = mask_inv)
# Take only region of logo from logo image.
img2_fg = cv2.bitwise_and(img2,img2,mask = mask)
# Put logo in ROI and modify the main image
dst = cv2.add(img1_bg,img2_fg)
# img1[0:rows, 0:cols ] = dst

# 将图片右下角矩形块 替换为 加过水印的矩形块
img1[b_rows-m_rows:b_rows, b_cols-m_cols:b_cols, ] = dst
cv2.imwrite('res.jpg', img1)
cv2.imshow('res',img1)
cv2.waitKey(0)
cv2.destroyAllWindows()