Graphics.DrawImage 会无意中修剪图像吗？

发布于 2024-07-12 12:46:18 字数 974 浏览 4 评论 0原文

我使用的代码接受位图并将其转换为 24 BPP，以便我可以在特别需要该文件格式的程序中使用它。这是代码：

    using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))
    {
       if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
       {
          using (Bitmap tempImage2 = new Bitmap(tempImage.Size.Width, tempImage.Size.Height,
             System.Drawing.Imaging.PixelFormat.Format24bppRgb))
          {
             using (Graphics g = Graphics.FromImage(tempImage2))
             {
                g.DrawImage(tempImage, new Point(0, 0));
             }
             RecognizeBitmap(pageToScan, tempImage2); //Thanks to Tim on this refactoring.
          }
       }
       else
          RecognizeBitmap(pageToScan, tempImage);
    }

我对上面的代码有两个问题：

对于特定的图像，我认为这剪掉了最右边的 200 tempImage2 右侧的像素。是这可能吗？这怎么可能发生了，我该如何阻止它？ A 我的朋友建议说可能与步幅有关正在使用的 TIFF 文件。
有没有将图像转换为 24 的更快方法内存中的BPP？

原文

I'm using code that takes a bitmap and converts it to 24 BPP so that I can use it in a program that specifically requires that file format. Here is the code:

    using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))
    {
       if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
       {
          using (Bitmap tempImage2 = new Bitmap(tempImage.Size.Width, tempImage.Size.Height,
             System.Drawing.Imaging.PixelFormat.Format24bppRgb))
          {
             using (Graphics g = Graphics.FromImage(tempImage2))
             {
                g.DrawImage(tempImage, new Point(0, 0));
             }
             RecognizeBitmap(pageToScan, tempImage2); //Thanks to Tim on this refactoring.
          }
       }
       else
          RecognizeBitmap(pageToScan, tempImage);
    }

I have two questions about the code above:

With a particular image, I think
that this clipped the rightmost 200
pixels right off of tempImage2. Is
this possible? How might this
happen, and how can I stop it? A
friend of mine suggested that it
might have to do with the stride of
the TIFF file being used.
Is there a
faster way to convert an image to 24
BPP in memory?

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一绘本一梦想 2024-07-19 12:46:18

更好的方法是使用 Bitmap.Clone 方法。这需要 PixelFormat 作为参数：

using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))    
{           
    if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
    {
        Rectangle r = new Rectangle(0, 0, tempImage.Width, tempImage.Height);
        RecognizeBitmap(pageToScan, tempImage.Clone(r, PixelFormat.Format24bppRgb);          
    }
    else                  
    {
        RecognizeBitmap(pageToScan, tempImage);    
    }
}

A better way is to use the Bitmap.Clone method. This takes a PixelFormat as a parameter:

using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))    
{           
    if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
    {
        Rectangle r = new Rectangle(0, 0, tempImage.Width, tempImage.Height);
        RecognizeBitmap(pageToScan, tempImage.Clone(r, PixelFormat.Format24bppRgb);          
    }
    else                  
    {
        RecognizeBitmap(pageToScan, tempImage);    
    }
}

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