在图像C#中查找图像 [英] Find an image in an image C#

问题描述

我扫描了填充了一些手写信息的文档(实际上是一个表格).

I have a scan of a document (a form actually) filled with some handwritten infos.

我有一个空格式的位图.

I have a bitmap of the form empty.

我该如何取消"打印的表格以仅提取手写内容.

how can i "cancel" the printed form to extract the handwritting only.

我使用C#... 谢谢 乔纳森

I use C#... Thanks Jonathan

推荐答案

您要做的是从带有手写内容的表单图像中减去空表单图像.这样就可以给您一个合理的手写图像.

What you want to do is subtract the empty form image from the image of the form with handwriting in it. This will give you a reasonable image of the handwriting alone.

请注意，这不会注册图像.注册将使它们排成一行，以使它们处于相同的方向，从而使减法获得最大的成功机会.如果您的图像对齐不佳，则必须查看图像配准.

Please note that this will not register the images. Registration will line them up so that they are at identical orientations to give the subtraction the best chance of success. If your images are poorly aligned you'll have to look into image registration.

这是我之前写过的代码片段，以执行类似的操作(此代码突出显示了红色的差异):

Here's a snippet of code I wrote a while back to do something similar (this code highlights differences in red):

        Bitmap b1 = new Bitmap(fname1);
        Bitmap b2 = new Bitmap(fname2);

        if (b1.Height != b2.Height || b1.Width != b2.Width) {
           MessageBox.Show("Input files are not the same dimensions!");
           Application.Exit();
        }

        totalPixels = b1.Height * b1.Width * 4;

        Bitmap outImg = new Bitmap(b1.Width, b1.Height, System.Drawing.Imaging.PixelFormat.Format32bppRgb);

        BitmapData b1Data = b1.LockBits(new Rectangle(0, 0, b1.Width, b1.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
        BitmapData b2Data = b2.LockBits(new Rectangle(0, 0, b1.Width, b1.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
        BitmapData oData = outImg.LockBits(new Rectangle(0, 0, b1.Width, b1.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);

        byte[] cur1 = new byte[b1Data.Stride * b1Data.Height];
        byte[] cur2 = new byte[b2Data.Stride * b2Data.Height];
        byte[] curOut = new byte[b2Data.Stride * b2Data.Height];

        Marshal.Copy(b1Data.Scan0, cur1, 0, b1Data.Stride * b1Data.Height);
        Marshal.Copy(b2Data.Scan0, cur2, 0, b2Data.Stride * b2Data.Height);

        for (int i = 0; i < b1Data.Stride * b1Data.Height; i += 4) {
           byte temp1 = cur1[i], temp2 = cur2[i], first = 0, second = 0;
           curOut[i] = 0;
           first = (byte) ((temp1 > temp2) ? temp1 - temp2 : temp2 - temp1);

           temp1 = cur1[i + 1];
           temp2 = cur2[i + 1];
           curOut[i + 1] = 0;
           second = (byte) ((temp1 > temp2) ? temp1 - temp2 : temp2 - temp1);

           temp1 = cur1[i + 2];
           temp2 = cur2[i + 2];
           curOut[i + 2] = (byte) ((temp1 > temp2) ? temp1 - temp2 : temp2 - temp1);
           curOut[i + 2] = (byte) ((first + second + curOut[i + 2]) * 255);

           curPixel = i;
        }

        Marshal.Copy(curOut, 0, oData.Scan0, b2Data.Stride * b2Data.Height);

        b1.UnlockBits(b1Data);
        b2.UnlockBits(b2Data);
        outImg.UnlockBits(oData);

        outImg.Save(outfile);

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