将opencv图像转换为gdi位图不起作用取决于图像大小 [英] Converting opencv image to gdi bitmap doesn't work depends on image size

问题描述

我有这个代码将opencv图像转换为位图：

I have this code that converts an opencv image to a bitmap:

  void processimage(MAT imageData)
  {
      Gdiplus::Bitmap bitmap(imageData.cols,imageData.rows,stride, PixelFormat24bppRGB,imageData.data);

   // do some work with bitmap
  }

它当图像大小为2748 X 3664时效果很好。但是我想要处理尺寸为1374 X 1832的图像，它不起作用。

It is working well when the size of image is 2748 X 3664. But I am tring to process an image wth size 1374 X 1832, it doesn't work.

错误是无效的参数（2）。

The error is invalid parameter(2).

我检查过并确认：

in 2748 * 3664：

in 2748 *3664:

• cols = 2748


• rows = 3664


• stride = 8244


• 图片继续。

• cols=2748
• rows=3664
• stride= 8244
• image is continues.

in 1374 X 1832

in 1374 X 1832

• cols = 1374


• rows = 1832


• stride = 4122


• 图片继续。

• cols=1374
• rows=1832
• stride= 4122
• image is continues.

所以一切看起来都对我不错，但它会产生错误。

So everything seems correct to me, but it generate error.

问题是什么？我该如何解决？

What is the problem and how can I fix it?

根据答案解释了为什么我无法创建位图。我终于以这种方式实现了它：

Based on answer which explained why I can not create bitmap. I finally implemented it in this way:

   Mat newImage;
   cvtColor(imageData, newImage, CV_BGR2BGRA);
   Gdiplus::Bitmap bitmap(newImage.cols,newImage.rows,newImage.step1(), PixelFormat32bppRGB,newImage.data);

如此有效，我将输入图像转换为每像素4个字节，然后使用将其转换为位图。

So effectively, I convert input image to a 4 byte per pixel and then use the convert it to bitmap.

Roger Rowland 的所有信用额度。

推荐答案

我认为问题是BMP格式的步幅必须是4的倍数。

I think the problem is that a BMP format must have a stride that is a multiple of 4.

您的放大图像的步幅为8244 ，这是有效的（8244/4 = 2061），但你的小图像的步幅为4122，而不是（4122/4 = 1030.5）。

Your larger image has a stride of 8244, which is valid (8244/4 = 2061) but your smaller image has a stride of 4122, which is not (4122/4 = 1030.5).

as 它在MSDN上说 stride 参数（我强调）：

As it says on MSDN for the stride parameter (with my emphasis):

整数，指定一个$开头之间的字节偏移量b $ b扫描线和下一个。这通常（但不一定）像素格式的
字节数（例如，每
像素16位的2）乘以位图的宽度。传递给此
参数的值必须是四的倍数。

假设您的步幅是的，我认为你唯一的选择是逐行复制它。所以，比如：

Assuming your stride is correct, I think you're only option is to copy it row by row. So, something like:

1. 伟大的 Gdiplus :: Bitmap 所需大小和格式


2. 使用 LockBits 获取位图像素数据。


3. 一次复制一行OpenCV图像。


4. 致电 UnlockBits 发布位图数据。

1. Great a Gdiplus::Bitmap of the required size and format
2. Use LockBits to get the bitmap pixel data.
3. Copy the OpenCV image one row at a time.
4. Call UnlockBits to release the bitmap data.

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