拉普拉斯金字塔后的重建图像与原始图像不同 [英] Reconstructed Image after Laplacian Pyramid Not the same as original image

问题描述

我正在将RGB图像转换为YCbCr，然后想要计算相同的拉普拉斯金字塔。在颜色转换之后，我正在试验OpenCV的图像金字塔教程中的代码，以找到图像的拉普拉斯金字塔，然后重建原始图像。但是，如果我将代码中的级别数增加到更高的数字（例如10），则重建的图像（转换回RGB后）与原始图像看起来不一样（图像看起来模糊 - 请参见下面的链接确切的图像）。我不确定为什么会这样。是否会在级别增加或代码中出现任何问题时发生？

I am converting an RGB image into YCbCr and then want to compute the laplacian pyramid for the same. After color conversion, I am experimenting with the code give on the Image Pyramid tutorial of OpenCV to find the Laplacian pyramid of an image and then reconstruct the original image. However, if I increase the number of levels in my code to a higher number, say 10, then the reconstructed image(after conversion back to RGB) does not look the same as the original image(image looks blurred - please see below link for the exact image). I am not sure why this is happening. Is it suppose to happen when the levels increase or is there anything wrong in the code?

frame = cv2.cvtColor(frame_RGB, cv2.COLOR_BGR2YCR_CB)
height = 10
Gauss = frame.copy()
gpA = [Gauss]
for i in xrange(height):
    Gauss = cv2.pyrDown(Gauss)
    gpA.append(Gauss)

lbImage = [gpA[height-1]]

for j in xrange(height-1,0,-1):
    GE = cv2.pyrUp(gpA[j])
    L = cv2.subtract(gpA[j-1],GE)
    lbImage.append(L)

ls_ = lbImage[0]     
for j in range(1,height,1):
    ls_ = cv2.pyrUp(ls_)
    ls_ = cv2.add(ls_,lbImage[j])

ls_ = cv2.cvtColor(ls_, cv2.COLOR_YCR_CB2BGR)                
cv2.imshow("Pyramid reconstructed Image",ls_)
cv2.waitKey(0)

作为参考，请参阅重建图像和原始图像。

For reference, please see the reconstructed image and the original image.

重建图片

原始图片

推荐答案

pyrDown模糊图像并对其进行下采样，丢失一些信息。保存的金字塔等级（ gpA [] 此处）包含越来越小的图像矩阵，但不保留被拒绝的信息详细信息（高频信息）。

pyrDown blurs an image and downsamples it, loosing some information. Saved pyramid levels (gpA[] here) contain smaller and smaller image matrices, but don't keep rejected information details (high-frequency ones).

所以重建的图像无法显示所有原始细节

So reconstructed image cannot show all original details

来自教程：
注意：当我们缩小图片大小时，我们实际上会丢失图片信息。

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