Bitmap.setPixels在Android下扭曲颜色

Question

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我需要从手机的相机中获取图像。我使用公式从YUV转换为RGB。然后我将RGB放入IntBuffer。然后我将IntBuffer中的像素复制到Bitmap中。这样可以得到正确的结果。 但我需要使用的不是IntBuffer，而是一个常见的int []数组。在这种情况下，函数bitmap.setPixels会产生不正确的结果。颜色是错误的。 第一张图片是正确的。第二个图像是int []的结果。

Android 4.1.1 HTC Desire X

    @Override
public void onPreviewFrame(byte[] data, Camera camera) {
    Size previewSize = parameters.getPreviewSize();
    int imageWidth = previewSize.width;
    int imageHeight = previewSize.height;

     if(toggleButton1.isChecked())
     {  
         if(ck==0)   
         {  

              Bitmap preview_bitmap = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888);
              Bitmap preview_bitmap2 = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888);

             final byte alpha = (byte) 255;
             int numPixels = imageWidth*imageHeight;

             IntBuffer intBuffer = IntBuffer.allocate(imageWidth*imageHeight);
             intBuffer.position(0);

             int buff[]= new int[imageWidth*imageHeight];

             int i=0;
             for (int y = 0; y < imageHeight; y++) {     
                for (int x = 0; x < imageWidth; x++) {   
                     int Y = data[y*imageWidth + x] & 0xff;

                     int xby2 = x/2;
                     int yby2 = y/2;
                     float U = (float)(data[numPixels + 2*xby2 + yby2*imageWidth] & 0xff) - 128.0f;
                     float V = (float)(data[numPixels + 2*xby2 + 1 + yby2*imageWidth] & 0xff) - 128.0f;
                     // Do the YUV -> RGB conversion
                     float Yf = 1.164f*((float)Y) - 16.0f;
                     int R = (int)(Yf + 1.596f*V);
                     int G = (int)(Yf - 0.813f*V - 0.391f*U);
                     int B = (int)(Yf            + 2.018f*U);

                     R = R < 0 ? 0 : R > 255 ? 255 : R;
                     G = G < 0 ? 0 : G > 255 ? 255 : G;
                     B = B < 0 ? 0 : B > 255 ? 255 : B;


                     intBuffer.put(alpha*16777216 + R*65536 + G*256 + B);
                     buff[i]=     (alpha*16777216 + R*65536 + G*256 + B);


                     i++;     
                 }
             }

            intBuffer.flip();

            preview_bitmap.copyPixelsFromBuffer(intBuffer); 
            preview_bitmap2.setPixels(buff,0,imageWidth,0,0,imageWidth,imageHeight);

            //imageView1.setImageBitmap(preview_bitmap);
            //imageView2.setImageBitmap(preview_bitmap2);

            save_SDcard(preview_bitmap,"pic1.jpg");
            save_SDcard(preview_bitmap2,"pic2.jpg");
             ck++;
         }
     }               
}

Answer 1

当我遇到类似的问题时，这是我用来交换红色和蓝色通道的简单代码

for (int i = 0; i < totalPixels; ++i) {
    // The alpha and green channels' positions are preserved while the red and blue are swapped
    pixelsBuffer[i] = ((pixelsBuffer[i] & 0xff00ff00)) | ((pixelsBuffer[i] & 0x000000ff) << 16) | ((pixelsBuffer[i] & 0x00ff0000) >> 16);
} 

Answer 2

您可以使用int []，然后只使用IntBuffer.wrap创建IntBuffer引用而不分配新内存。 Bitmap.copyPixelsFromBuffer（）复制原始像素而不修改它们，setPixels正在进行alpha乘法，可能还有格式转换（所有外观都有某种ARGB / BGRA转换。

尝试这些调整以继续使用copyPixelsFromBuffer（）和int []：

@Override
public void onPreviewFrame(byte[] data, Camera camera) {
    Size previewSize = parameters.getPreviewSize();
    int imageWidth = previewSize.width;
    int imageHeight = previewSize.height;

     if(toggleButton1.isChecked())
     {  
         if(ck==0)   
         {  

              Bitmap preview_bitmap = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888);
              Bitmap preview_bitmap2 = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888);

             final byte alpha = (byte) 255;
             int numPixels = imageWidth*imageHeight;
             int buff[]= new int[numPixels];

             int i=0;
             for (int y = 0; y < imageHeight; y++) {     
                for (int x = 0; x < imageWidth; x++) {   
                     int Y = data[y*imageWidth + x] & 0xff;

                     int xby2 = x/2;
                     int yby2 = y/2;
                     float U = (float)(data[numPixels + 2*xby2 + yby2*imageWidth] & 0xff) - 128.0f;
                     float V = (float)(data[numPixels + 2*xby2 + 1 + yby2*imageWidth] & 0xff) - 128.0f;
                     // Do the YUV -> RGB conversion
                     float Yf = 1.164f*((float)Y) - 16.0f;
                     int R = (int)(Yf + 1.596f*V);
                     int G = (int)(Yf - 0.813f*V - 0.391f*U);
                     int B = (int)(Yf            + 2.018f*U);

                     R = R < 0 ? 0 : R > 255 ? 255 : R;
                     G = G < 0 ? 0 : G > 255 ? 255 : G;
                     B = B < 0 ? 0 : B > 255 ? 255 : B;

                     // better implementation than multiplying
                     buff[i] = Color.argb(alpha,R,G,B);
                     i++;     
                 }
             }

            // just wrap your buff
            IntBuffer intBuffer = IntBuffer.wrap(buff);

            preview_bitmap.copyPixelsFromBuffer(intBuffer); 
            preview_bitmap2.setPixels(buff,0,imageWidth,0,0,imageWidth,imageHeight);

            //imageView1.setImageBitmap(preview_bitmap);
            //imageView2.setImageBitmap(preview_bitmap2);

            save_SDcard(preview_bitmap,"pic1.jpg");
            save_SDcard(preview_bitmap2,"pic2.jpg");
             ck++;
         }
     }               
}