显示时图像更改形状 [英] Image change the shape when displaying

问题描述

我尝试显示此图片，因为我在我的目录中有此图片

I am trying to display this image as i have this image in my directory

但我用此代码显示它

Mat img=imread("D:\\vig.png");
imshow("image",img);
waitKey();
imwrite("D:\\img.jpg",img);

同样的图像显示如下

有什么问题？ / p>

Whats wrong with it

推荐答案

您的晕影只在alpha [第4]频道，并且它看起来颠倒（这里的不透明度值）。

your vignette is only in the alpha [4th] channel, and also it looks inverted (opacity values here).

（您的第一张照片似乎显示一个白色图片（或背景）的正片复合图片，可能来自photoshop等）

(your 1st picture seems to show a proper alpha composite with a white image(or background), that's probably from photoshop or the like. )

Mat img=imread("vig.png",-1); // load 'as is', don't convert to bgr !!
Mat ch[4]; 
split(img,ch);

Mat im2 = ch[3];              // here's the vignette

// im2 = 255 - im2;           // eventually cure the inversion

imshow("image",im2);
waitKey();
imwrite("img.jpg",im2);

注意，opencv不会做任何alpha合成，你必须滚动自己的公式。

again, note, that opencv won't do any alpha-compositing, you'll have to roll your own formulas for that.

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