変換時に画像の端が切り取られるImageSource

TWAINのスキャナからDIBをBitmapSourceに変換するのに、以下のコードを使用しますが、画像の端が切り取られています。画像サイズはソース画像とは異なります。ハンドヘルドイメージのときに以下のコードに何か間違っていますか？変換時に画像の端が切り取られるImageSource

/// <summary> 
/// Get managed BitmapSource from a DIB provided as a low level windows hadle 
/// 
/// Notes: 
/// Data is copied from the source so the windows handle can be saftely discarded 
/// even when the BitmapSource is in use. 
/// 
/// Only a subset of possible DIB forrmats is supported. 
/// 
/// </summary> 
/// <param name="dibHandle"></param> 
/// <returns>A copy of the image in a managed BitmapSource </returns> 
/// 
public static BitmapSource FormHDib(IntPtr dibHandle) 
{ 
    BitmapSource bs = null; 
    IntPtr bmpPtr = IntPtr.Zero; 
    bool flip = true; // vertivcally flip the image 

    try { 
     bmpPtr = Win32.GlobalLock(dibHandle); 
     Win32.BITMAPINFOHEADER bmi = new Win32.BITMAPINFOHEADER(); 
     Marshal.PtrToStructure(bmpPtr, bmi); 

     if (bmi.biSizeImage == 0) 
      bmi.biSizeImage = (uint)(((((bmi.biWidth * bmi.biBitCount) + 31) & ~31) >> 3) * bmi.biHeight); 

     int palettSize = 0; 

     if (bmi.biClrUsed != 0) 
      throw new NotSupportedException("DibToBitmap: DIB with pallet is not supported"); 

     // pointer to the beginning of the bitmap bits 
     IntPtr pixptr = (IntPtr)((int)bmpPtr + bmi.biSize + palettSize); 

     // Define parameters used to create the BitmapSource. 
     PixelFormat pf = PixelFormats.Default; 
     switch (bmi.biBitCount) { 
      case 32: 
       pf = PixelFormats.Bgr32; 
       break; 
      case 24: 
       pf = PixelFormats.Bgr24; 
       break; 
      case 8: 
       pf = PixelFormats.Gray8; 
       break; 
      case 1: 
       pf = PixelFormats.BlackWhite; 
       break; 
      default: // not supported 
       throw new NotSupportedException("DibToBitmap: Can't determine picture format (biBitCount=" + bmi.biBitCount + ")"); 
      // break; 
     } 
     int width = bmi.biWidth; 
     int height = bmi.biHeight; 
     int stride = (int)(bmi.biSizeImage/height); 
     byte[] imageBytes = new byte[stride * height]; 

     //Debug: Initialize the image with random data. 
     //Random value = new Random(); 
     //value.NextBytes(rawImage); 

     if (flip) { 
      for (int i = 0, j = 0, k = (height - 1) * stride; i < height; i++, j += stride, k -= stride) 
       Marshal.Copy(((IntPtr)((int)pixptr + j)), imageBytes, k, stride); 
     } else { 
      Marshal.Copy(pixptr, imageBytes, 0, imageBytes.Length); 
     } 

     int xDpi = (int)Math.Round(bmi.biXPelsPerMeter * 2.54/100); // pels per meter to dots per inch 
     int yDpi = (int)Math.Round(bmi.biYPelsPerMeter * 2.54/100); 

     // Create a BitmapSource. 
     bs = BitmapSource.Create(width, height, xDpi, yDpi, pf, null, imageBytes, stride); 
     Win32.GlobalUnlock(pixptr); 
     Win32.GlobalFree(pixptr); 
     pixptr = IntPtr.Zero; 
     imageBytes = null; 
     bmi = null; 
    } catch (Exception ex) { 
     //string msg = ex.Message; 
    } 
    finally { 
     // cleanup 
     if (bmpPtr != IntPtr.Zero) { // locked sucsessfully 
      Win32.GlobalUnlock(dibHandle); 
     } 
    } 
    Win32.GlobalUnlock(bmpPtr); 
    Win32.GlobalFree(bmpPtr); 
    bmpPtr = IntPtr.Zero; 

    return bs; 
}

このコードはhereです。

出典

2016-06-29 Xiaokun