高手请进，C#中如何通过地址方式遍历bitmap在内存中的数据？

Question

本帖最后由 vbdotnet2001 于 2010-05-28 18:05:43 编辑

Answer 1

        /// <summary>
        /// 指针扫描bmp by skep99
        /// </summary>
        unsafe void dealbmp()
        {
            //lock
            GraphicsUnit unit = GraphicsUnit.Pixel;
            RectangleF boundsF = bitmap.GetBounds(ref unit);
            Rectangle bounds = new Rectangle((int)boundsF.X,
                (int)boundsF.Y,
                (int)boundsF.Width,
                (int)boundsF.Height);            width = (int)boundsF.Width * sizeof(PixelData);
            if (width % 4 != 0)
            {
                width = 4 * (width / 4 + 1);
            }            bitmapData =
                bitmap.LockBits(bounds, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);            pBase = (Byte*)bitmapData.Scan0.ToPointer();            //处理
            Point size = PixelSize;            for (int x = 0; x < size.X; x++)
            {
                for (int y = 0; y < size.Y; y++)
                {
                    PixelData* pPixel = PixelAt(x, y);                    int value = (pPixel->red + pPixel->green + pPixel->blue) / 3;
                    pPixel->red = (byte)value;
                    pPixel->green = (byte)value;
                    pPixel->blue = (byte)value;
                }
            }            //unlock
            bitmap.UnlockBits(bitmapData);
            bitmapData = null;
            pBase = null;
        }

Answer 2

using System.IO;
using System.Drawing;
Bitmap image = new Bitmap();
MemoryStream ms = new MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
ms.ToArray();

Answer 3

GetPixel(j, i)直接获取对应像素的颜色值如果想操作指针的话
不放用：
unsafe
{
fixed *xxx = address;
...
}

Answer 4

GetPixel方式极慢。
能详细说明如何使用指针直接访问吗？

Answer 5

我的代码下面的语句需要在循环中遍历short数组，如下：
                for (int y_value = 0; y_value < BitmapHeight; y_value++)
                {
                    xyValue = y_value * bmp_width + x_value;
                    if (rgbValues[xyValue] == 0)
                    {
                        TempBuffer[j] |= OrBytes[i];
                        if ((TempBuffer[j] == 0xfd) || (TempBuffer[j] == 0xfe) || (TempBuffer[j] == 0xff))
                        {
                            TempBuffer[j + 1] = (byte)(TempBuffer[j] ^ 0x20);
                            TempBuffer[j] = 0xfd;
                            j++;
                        }
                    }
                    i++;
                    if (i == 8)
                    {
                        j++;
                        i = 0;
                    }
                }最好能直接告诉我如何换成直接内存方式。不胜感激。

Answer 6

下面是我代码的后续部分，需要在循环中遍历short数组。if (rgbValues[xyValue] == 0)这句相当浪费时间。
                for (int y_value = 0; y_value < BitmapHeight; y_value++)
                {
                    xyValue = y_value * bmp_width + x_value;
                    if (rgbValues[xyValue] == 0)
                    {
                        TempBuffer[j] |= OrBytes[i];
                        if ((TempBuffer[j] == 0xfd) || (TempBuffer[j] == 0xfe) || (TempBuffer[j] == 0xff))
                        {
                            TempBuffer[j + 1] = (byte)(TempBuffer[j] ^ 0x20);
                            TempBuffer[j] = 0xfd;
                            j++;
                        }
                    }
                    i++;
                    if (i == 8)
                    {
                        j++;
                        i = 0;
                    }
                }

Answer 7

http://topic.csdn.net/u/20100312/19/C8AD00FD-E3D2-42B5-9B39-AD55886346D5.htmlhttp://topic.csdn.net/u/20100503/12/4C9B6CAE-D56A-47D2-A864-C64E91323817.html

Answer 8

谢谢各位，发现用指针操作和Marshal.Copy到short[]遍历速度基本一样，好在节省了不少内存，感谢大家帮助。晚点结贴，看看各位还有没有更好的理解。