每像素16位图像编辑 [英] 16 Bit per Pixel image editing

问题描述

嗨！
我正在尝试编辑16位图像数据，但无法访问每个像素的完整16位.
以下代码可完美处理8位图像.

Hi!
I´m trying to edit 16 bit image data but I can´t access the full 16 bit of each pixel.
The following code is working flawlessly with 8 bit images.

private void ImageEditing()
{            
    //opening a 8 bit per pixel jpg image
    Bitmap bmp = new Bitmap("Image.jpg");

    int Width = bmp.Width;
    int Height = bmp.Height;

    //creating the bitmapdata and lock bits
    System.Drawing.Rectangle rec = new System.Drawing.Rectangle(0, 0, Width, Height);
    BitmapData bmd = bmp.LockBits(rec, ImageLockMode.ReadOnly, bmp.PixelFormat);

    unsafe
    {
        //iterating through all the pixels in y direction
        for (int y = 0; y < Height; y++)
        {
            //getting the pixels of current row
            byte* row = (byte*)bmd.Scan0 + (y * bmd.Stride);

            //iterating through all the pixels in x direction
            for (int x = 0; x < Width; x++)
            {
                //getting index of current pixel (3 because of the 3 * 8bits per pixel)
                int index = x * 3;

                //getting R, G and B values
                byte R = row[index + 2];
                byte G = row[index + 1];
                byte B = row[index];
            }
        }
    }

    //unlocking bits and disposing image
    bmp.UnlockBits(bmd);
    bmp.Dispose();
}

如果我想将其调整为16位并用ushorts(无符号16位整数)替换字节，还打开一个16位图像，则可以编译该图像，但在图片中间某处会收到AccesViolationException.

有任何想法我做错了或有不同的解决方法吗?

除了一些有关如何显示Raw image data的文章，在这里或与Google无关，我找不到任何东西.在这种情况下，因为我没有那个.

希望大家能帮忙
Johannes

If I want to adapt it to 16 bit and replace bytes with ushorts(unsigned 16 bit integer) and also open a 16 bit image it compiles but I get an AccesViolationException somewhere in the middle of the picture.

Any ideas what I did wrong or are there any different approches?

I couldn´t find anything here or with google except some article on how to display Raw image data which doesn´t help me in this case as I don´t have that.

I hope you guys can help
Johannes

推荐答案

该代码基本上是正确的，但是它不能普遍起作用，只是因为您的所有移位都取决于您从未使用过的像素格式.您仅将bmp.PixelFormat作为参数透明地传递给新的位图.除非您分析System.Drawing.PixelFormat的值(可能需要使用if或switch)并相应地移动指针算法，否则代码无法正常工作.请参阅:
http://msdn.microsoft.com/en-us/library/system. drawing.image.pixelformat.aspx [ ^ ]，
http://msdn.microsoft.com/en-us/library/system. drawing.imaging.pixelformat.aspx [ ^ ].

—SA

The code is basically correct, but it cannot universally work, just because all your shifts will depends on pixel format, which you never use. You only transparently pass bmp.PixelFormat as a parameter to a new bitmap. The code cannot work correctly unless you analyze the value of System.Drawing.PixelFormat (you might need to use if or switch) and shift your pointer arithmetic accordingly. Please see:
http://msdn.microsoft.com/en-us/library/system.drawing.image.pixelformat.aspx[^],
http://msdn.microsoft.com/en-us/library/system.drawing.imaging.pixelformat.aspx[^].

—SA

我终于找到了解决方法！
因为我将行从字节更改为ushort，所以行的长度只有一半.

因此对于16位图像，代码如下所示:

I finally found the solution!
Because I changed the row from byte to ushort the row has only half the length.

so for a 16 bit image the code would look like this:

private void ImageEditing()
{            
    //opening a 16 bit per pixel tif image
    Bitmap bmp = new Bitmap("Image.tif");
 
    int Width = bmp.Width;
    int Height = bmp.Height;
 
    //creating the bitmapdata and lock bits
    System.Drawing.Rectangle rec = new System.Drawing.Rectangle(0, 0, Width, Height);
    BitmapData bmd = bmp.LockBits(rec, ImageLockMode.ReadOnly, bmp.PixelFormat);
 
    unsafe
    {
        //iterating through all the pixels in y direction
        for (int y = 0; y < Height; y++)
        {
            //getting the pixels of current row
            ushort* row = (ushort*)bmd.Scan0 + (y * bmd.Stride / 2);
 
            //iterating through all the pixels in x direction
            for (int x = 0; x < Width; x++)
            {
                //getting index of current pixel (3 because of the 3 * 16bits per pixel)
                int index = x * 3;
 
                //getting R, G and B values
                ushort R = row[index + 2];
                ushort G = row[index + 1];
                ushort B = row[index];
            }
        }
    }
 
    //unlocking bits and disposing image
    bmp.UnlockBits(bmd);
    bmp.Dispose();
}

这篇关于每像素16位图像编辑的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！