Question

这是方法：

public static Bitmap FastComparison(Bitmap bmp1,Bitmap bmp2)
{
            Bitmap bmp3 = new Bitmap(512,512);
            PixelFormat pxf = PixelFormat.Format24bppRgb;
            Rectangle rect = new Rectangle(0, 0, bmp1.Width, bmp1.Height);
            BitmapData bmpData1 = bmp1.LockBits(rect, ImageLockMode.ReadWrite, pxf);
            BitmapData bmpData2 = bmp2.LockBits(rect, ImageLockMode.ReadWrite, pxf);
            BitmapData bmpData3 = bmp3.LockBits(rect, ImageLockMode.ReadWrite, pxf);

            IntPtr ptr1 = bmpData1.Scan0;
            IntPtr ptr2 = bmpData2.Scan0;
            IntPtr ptr3 = bmpData3.Scan0;

            int numBytes = bmpData1.Stride * bmp1.Height;
            byte[] rgbValues1 = new byte[numBytes];
            Marshal.Copy(ptr1, rgbValues1, 0, numBytes);
            bmp1.UnlockBits(bmpData1);

            byte[] rgbValues2 = new byte[numBytes];
            Marshal.Copy(ptr2, rgbValues2, 0, numBytes);
            bmp2.UnlockBits(bmpData2);


            for (int counter = 0; counter < rgbValues1.Length; counter += 3)
            {
                int  dr, dg, db;
                dr = (int)rgbValues1[counter] - (int)rgbValues2[counter];
                dg = (int)rgbValues1[counter + 1] - (int)rgbValues2[counter + 1];
                db = (int)rgbValues1[counter + 2] - (int)rgbValues2[counter + 2];

                int error = dr * dr + dg * dg + db * db;
                if (error < tolerancenumeric)
                {
                    rgbValues1[counter] = 0;
                    rgbValues1[counter + 1] = 0;
                    rgbValues1[counter + 2] = 0;
                }

            }
            Marshal.Copy(rgbValues1, 0, ptr3, numBytes);
            return bmp1;
}

这就是我在Form1中使用/调用它的方式：

private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
              CloudEnteringAlert.tolerancenum = (int)numericUpDown1.Value;
              pictureBox1.Image = CloudEnteringAlert.FastComparison(bitmapwithclouds, bitmapwithoutclouds);
}

我想要的是更改公差，所以最后我会得到一个结果，其中图像变量bmp1将仅在黑色背景上显示云。

我做错了什么？

这是我现在更改它的新方法。现在我只得到黑色图像：

public static Bitmap FastComparison(Bitmap bmp1,Bitmap bmp2)
        {
            Bitmap bmp3 = new Bitmap(512,512);
            PixelFormat pxf = PixelFormat.Format24bppRgb;
            Rectangle rect = new Rectangle(0, 0, bmp1.Width, bmp1.Height);
            BitmapData bmpData1 = bmp1.LockBits(rect, ImageLockMode.ReadWrite, pxf);
            BitmapData bmpData2 = bmp2.LockBits(rect, ImageLockMode.ReadWrite, pxf);
            BitmapData bmpData3 = bmp3.LockBits(rect, ImageLockMode.ReadWrite, pxf);

            IntPtr ptr1 = bmpData1.Scan0;
            IntPtr ptr2 = bmpData2.Scan0;
            IntPtr ptr3 = bmpData3.Scan0;

            int numBytes = bmpData1.Stride * bmp1.Height;
            byte[] rgbValues1 = new byte[numBytes];
            Marshal.Copy(ptr1, rgbValues1, 0, numBytes);
            bmp1.UnlockBits(bmpData1);

            byte[] rgbValues2 = new byte[numBytes];
            Marshal.Copy(ptr2, rgbValues2, 0, numBytes);
            bmp2.UnlockBits(bmpData2);


            for (int counter = 0; counter < rgbValues1.Length; counter += 3)
            {
                int  dr, dg, db;
                dr = (int)rgbValues1[counter] - (int)rgbValues2[counter];
                dg = (int)rgbValues1[counter + 1] - (int)rgbValues2[counter + 1];
                db = (int)rgbValues1[counter + 2] - (int)rgbValues2[counter + 2];

                int error = tolerancenumeric * tolerancenumeric + tolerancenumeric + tolerancenumeric + tolerancenumeric * tolerancenumeric;//dr * dr + dg * dg + db * db;
                if (error < tolerancenumeric)
                {

                }
                else
                {
                    rgbValues1[counter] = 0;
                    rgbValues1[counter + 1] = 0;
                    rgbValues1[counter + 2] = 0;
                }

            }
            Marshal.Copy(rgbValues1, 0, ptr3, numBytes);
            bmp3.UnlockBits(bmpData3);
            return bmp3;
        }

Answer 1

您似乎没有为超出容差的像素设置任何像素值。在其他情况下，您将它们设置为黑色。黑色实际上是默认的，因此您只需要设置“错误”像素。

另外你应该返回bmp3（需要解锁，顺便说一下），而不是bmp1。

最后，应该创建大小为bmp1或bmp2的bmp3（需要相同）。

我正在尝试使用LockBits比较两个图像，但它不起作用 - 为什么？

1 个答案: