android - 从 android 相机解码 NV21 图像，但它的颜色不适合图像

Question

这是我用来旋转图像的代码。我需要通过网络发送它。图像正在正确旋转，但我得到的图像没有正确的颜色。我在 cpp 中将此代码编写为 native 代码。 DecodeNV21() 有 3 个参数宽度、高度、旋转。我得到的宽度和高度是 640,480。如果旋转是纵向变量旋转为 1，高度和宽度将为 640,480。旋转为 0，即横向，则宽度和高度 640 和 480。请知道的人帮我解决这个问题。纵向模式旋转是正确的。但横向模式有问题。

void DecodeNV21(int SrcHeight,int SrcWidth,int rotation)
 /* decodes NV21-encoded image data, which is the default camera preview image format. */
 {
  //int SrcWidth = encoderContext.m_width;
  //int SrcHeight = encoderContext.m_height;
  int Rotate = rotation;
  int Alpha = 0xFF;
   int AlphaMask = Alpha << 24;
 /* Rotation involves accessing either the source or destination pixels in a
   non-sequential fashion. Since the source is smaller, I figure it's less
   cache-unfriendly to go jumping around that. */
    int DstWidth = (Rotate & 1) != 0 ? SrcHeight : SrcWidth;
    int DstHeight = (Rotate & 1) != 0 ? SrcWidth : SrcHeight;
    bool DecrementRow = Rotate > 1;
    bool DecrementCol = Rotate == 1 || Rotate == 2;
    int LumaRowStride = (Rotate & 1) != 0 ? 1 : SrcWidth;
    int LumaColStride = (Rotate & 1) != 0 ? SrcWidth : 1;
    int ChromaRowStride = (Rotate & 1) != 0 ? 2 : SrcWidth;
    int ChromaColStride = (Rotate & 1) != 0 ? SrcWidth : 2;
  //  LOGME("DecodeNV21 decoding w:%d,h:%d,DecrementRow:%d,ChromaRowStride:%d, DecrementCol:%d,ChromaColStride:%d,LumaRowStride%d,LumaColStride:%d",DstWidth,DstHeight,DecrementRow,ChromaRowStride, DecrementCol,ChromaColStride,LumaRowStride,LumaColStride);
   int dst = 0;
   int i=0;
   for (int row = DecrementRow ? DstHeight : 0;;)
     {
       if (row == (DecrementRow ? 0 : DstHeight))
           break;
       if (DecrementRow)
         {
           --row;
         } /*if*/
       for (int col = DecrementCol ? DstWidth : 0;;)
         {
           if (col == (DecrementCol ? 0 : DstWidth))
               break;
           if (DecrementCol)
             {
               --col;
             } /*if*/
            int Y = 0xff & (int)byte_array[row * LumaRowStride + col * LumaColStride]; /* [0 .. 255] */
         /* U/V data follows entire luminance block, downsampled to half luminance
           resolution both horizontally and vertically */
         /* decoding follows algorithm shown at
           <http://www.mail-archive.com/android-developers@googlegroups.com/msg14558.html>,
           except it gets red and blue the wrong way round */
            int Cr =
               (0xff & (int)byte_array[SrcHeight * SrcWidth + row / 2 * ChromaRowStride + col / 2 * ChromaColStride]) - 128;
                 /* [-128 .. +127] */
            int Cb =
               (0xff & (int)byte_array[SrcHeight * SrcWidth + row / 2 * ChromaRowStride + col / 2 * ChromaColStride + 1]) - 128;
                 /* [-128 .. +127] */
                   int r,g,b;
           int color =
                   AlphaMask
               |
                       (r=max(
                           min(
                               (int)(
                                       Y
                                   +
                                       Cr
                                   +
                                       (Cr >> 1)
                                   +
                                       (Cr >> 2)
                                   +
                                       (Cr >> 6)
                               ),
                               255
                             ),
                             0
                         ))
                   <<
                       16 /* red */
               |
                       (g=max(
                           min(
                               (int)(
                                       Y
                                   -
                                       (Cr >> 2)
                                   +
                                       (Cr >> 4)
                                   +
                                       (Cr >> 5)
                                   -
                                       (Cb >> 1)
                                   +
                                       (Cb >> 3)
                                   +
                                       (Cb >> 4)
                                   +
                                       (Cb >> 5)
                               ),
                               255
                             ),
                           0
                         ))
                   <<
                       8 /* green */
               |  (b=max(
                       min(
                           (int)(
                                   Y
                               +
                                   Cb
                               +
                                   (Cb >> 2)
                               +
                                   (Cb >> 3)
                               +
                                   (Cb >> 5)
                           ),
                           255
                         ),
                       0
                     )); /* blue */
                        //color = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
             TypeConvert::udwordToBytes(color, encoderContext.m_in_Array_Encode,i * 4);
      i++;
           if (!DecrementCol)
             {
               ++col;
             } /*if*/
         } /*for*/
       if (!DecrementRow)
         {
           ++row;
         } /*if*/
     } /*for*/
 } /*DecodeNV21*/

Answer 1

我真的不想整理你的旧代码，只是让我粘贴我采用的解决方案(从我忘记的地方得到它......)将图像旋转 90、180、270 度并返回一个字节数组.因此，例如，您处于纵向模式，您可以将后置摄像头旋转 90 度，将前置摄像头旋转 270 度。其他轮换方式可以按照类似的方式实现。我认为这应该足以让您继续这条路。

private byte[] rotateYUV420Degree90(byte[] data, int imageWidth, int imageHeight)
{

    byte [] yuv = new byte[imageWidth*imageHeight*3/2];
    // Rotate the Y luma
    int i = 0;
    for(int x = 0;x < imageWidth;x++)
    {
        for(int y = imageHeight-1;y >= 0;y--)                               
        {
            yuv[i] = data[y*imageWidth+x];
            i++;
        }

    }
    // Rotate the U and V color components 
    i = imageWidth*imageHeight*3/2-1;
    for(int x = imageWidth-1;x > 0;x=x-2)
    {
        for(int y = 0;y < imageHeight/2;y++)                                
        {
            yuv[i] = data[(imageWidth*imageHeight)+(y*imageWidth)+x];
            i--;
            yuv[i] = data[(imageWidth*imageHeight)+(y*imageWidth)+(x-1)];
            i--;
        }
    }
    return yuv;
}

private byte[] rotateYUV420Degree180(byte[] data, int imageWidth, int imageHeight) 
{
    byte [] yuv = new byte[imageWidth*imageHeight*3/2];
    int i = 0;
    int count = 0;

    for (i = imageWidth * imageHeight - 1; i >= 0; i--) {
        yuv[count] = data[i];
        count++;
    }

    i = imageWidth * imageHeight * 3 / 2 - 1;
    for (i = imageWidth * imageHeight * 3 / 2 - 1; i >= imageWidth
            * imageHeight; i -= 2) {
        yuv[count++] = data[i - 1];
        yuv[count++] = data[i];
    }
    return yuv;
}

private byte[] rotateYUV420Degree270(byte[] data, int imageWidth, int imageHeight) 
{
    byte [] yuv = new byte[imageWidth*imageHeight*3/2];
    int nWidth = 0, nHeight = 0;
    int wh = 0;
    int uvHeight = 0;
    if(imageWidth != nWidth || imageHeight != nHeight)
    {
        nWidth = imageWidth;
        nHeight = imageHeight;
        wh = imageWidth * imageHeight;
        uvHeight = imageHeight >> 1;//uvHeight = height / 2
    }

    //–˝◊™Y
    int k = 0;
    for(int i = 0; i < imageWidth; i++) {
        int nPos = 0;
        for(int j = 0; j < imageHeight; j++) {
            yuv[k] = data[nPos + i];
            k++;
            nPos += imageWidth;
        }
    }

    for(int i = 0; i < imageWidth; i+=2){
        int nPos = wh;
        for(int j = 0; j < uvHeight; j++) {
            yuv[k] = data[nPos + i];
            yuv[k + 1] = data[nPos + i + 1];
            k += 2;
            nPos += imageWidth;
        }
    }
    return rotateYUV420Degree180(yuv,imageWidth,imageHeight);
}