cv2.addWeighted 图像叠加or图像混合加权

Python-OpenCV 图像叠加or图像混合加权实现
函数说明

cv2.addWeighted(src1, alpha, src2, beta, gamma[, dst[, dtype]]) → dst

参数说明

src1 – first input array.
alpha – weight of the first array elements.
src2 – second input array of the same size and channel number as src1.
beta – weight of the second array elements.
dst – output array that has the same size and number of channels as the input arrays.
gamma – scalar added to each sum.
dtype – optional depth of the output array; when both input arrays have the same depth, dtype can be set to -1, which will be equivalent to src1.depth().

此函数可以用一下矩阵表达式来代替：

dst = src1 * alpha + src2 * beta + gamma;

注意：由参数说明可以看出，被叠加的两幅图像必须是尺寸相同、类型相同的；并且，当输出图像array的深度为CV_32S时，这个函数就不适用了，这时候就会内存溢出或者算出的结果压根不对。

CV_32S is a signed 32bit integer value for each pixel
代码：

def addImage(img1_path, img2_path):
    img1 = cv2.imread(img1_path)
    img = cv2.imread(img2_path)
    h, w, _ = img1.shape
    # 函数要求两张图必须是同一个size
    img2 = cv2.resize(img, (w,h), interpolation=cv2.INTER_AREA)
    #print img1.shape, img2.shape
    #alpha，beta，gamma可调
    alpha = 0.7
    beta = 1-alpha
    gamma = 0
    img_add = cv2.addWeighted(img1, alpha, img2, beta, gamma)
    cv2.namedWindow('addImage')
    cv2.imshow('img_add',img_add)
    cv2.waitKey()
    cv2.destroyAllWindows()

img1:

img2:

叠加后结果：

（1）图1的权重为0.7，图二的权重为0.3， gamma为0 的结果：
img_add1

(2）图1的权重为0.7，图二的权重为0.3， gamma为100 的结果