将 android.media.Image (YUV_420_888) 转换为位图

Question

我正在尝试使用 camera2 api 实现相机预览图像数据处理，如此处所建议：Camera preview image data processing with Android L and Camera2 API。

我使用 onImageAvailableListener 成功接收到回调，但为了将来的处理，我需要从 YUV_420_888 android.media.Image 获取位图。我搜索了类似的问题，但 none 个问题对我有所帮助。

能否建议我如何将 android.media.Image (YUV_420_888) 转换为位图或者是否有更好的监听预览帧的方法？

Answer 1

我写了一些关于这个的代码，它是 YUV 数据预览并将其更改为 JPEG 数据，我可以用它来保存为位图，byte[] 或其他。（你可以看到 class "Allocation"）。

SDK文档说：
"For efficient YUV processing with android.renderscript: Create a RenderScript Allocation with a supported YUV type, the IO_INPUT flag, and one of the sizes returned by getOutputSizes(Allocation.class), Then obtain the Surface with getSurface()."

这是代码，希望对你有帮助：https://github.com/pinguo-yuyidong/Camera2/blob/master/camera2/src/main/rs/yuv2rgb.rs

Answer 2

有关更简单的解决方案，请在此处查看我的实现：

Conversion YUV 420_888 to Bitmap (full code)

该函数将 media.image 作为输入，并根据 y、u 和 v 平面创建三个 RenderScript 分配。它遵循维基百科插图中所示的 YUV_420_888 逻辑。

然而，这里我们有三个单独的图像平面用于 Y、U 和 V 通道，因此我将它们视为三个字节[]，即 U8 分配。 y 分配的大小为 width * height 字节，而 u 和 v 分配的大小为 width * height/4 字节，反映了每个 u 字节覆盖 4 个像素（每个 v 字节也是如此）的事实。

Answer 3

您可以使用内置的 Renderscript intrinsic ScriptIntrinsicYuvToRGB. Code taken from :

@Override
public void onImageAvailable(ImageReader reader)
{
    // Get the YUV data

    final Image image = reader.acquireLatestImage();
    final ByteBuffer yuvBytes = this.imageToByteBuffer(image);

    // Convert YUV to RGB

    final RenderScript rs = RenderScript.create(this.mContext);

    final Bitmap        bitmap     = Bitmap.createBitmap(image.getWidth(), image.getHeight(), Bitmap.Config.ARGB_8888);
    final Allocation allocationRgb = Allocation.createFromBitmap(rs, bitmap);

    final Allocation allocationYuv = Allocation.createSized(rs, Element.U8(rs), yuvBytes.array().length);
    allocationYuv.copyFrom(yuvBytes.array());

    ScriptIntrinsicYuvToRGB scriptYuvToRgb = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));
    scriptYuvToRgb.setInput(allocationYuv);
    scriptYuvToRgb.forEach(allocationRgb);

    allocationRgb.copyTo(bitmap);

    // Release

    bitmap.recycle();

    allocationYuv.destroy();
    allocationRgb.destroy();
    rs.destroy();

    image.close();
}

private ByteBuffer imageToByteBuffer(final Image image)
{
    final Rect crop   = image.getCropRect();
    final int  width  = crop.width();
    final int  height = crop.height();

    final Image.Plane[] planes     = image.getPlanes();
    final byte[]        rowData    = new byte[planes[0].getRowStride()];
    final int           bufferSize = width * height * ImageFormat.getBitsPerPixel(ImageFormat.YUV_420_888) / 8;
    final ByteBuffer    output     = ByteBuffer.allocateDirect(bufferSize);

    int channelOffset = 0;
    int outputStride = 0;

    for (int planeIndex = 0; planeIndex < 3; planeIndex++)
    {
        if (planeIndex == 0)
        {
            channelOffset = 0;
            outputStride = 1;
        }
        else if (planeIndex == 1)
        {
            channelOffset = width * height + 1;
            outputStride = 2;
        }
        else if (planeIndex == 2)
        {
            channelOffset = width * height;
            outputStride = 2;
        }

        final ByteBuffer buffer      = planes[planeIndex].getBuffer();
        final int        rowStride   = planes[planeIndex].getRowStride();
        final int        pixelStride = planes[planeIndex].getPixelStride();

        final int shift         = (planeIndex == 0) ? 0 : 1;
        final int widthShifted  = width >> shift;
        final int heightShifted = height >> shift;

        buffer.position(rowStride * (crop.top >> shift) + pixelStride * (crop.left >> shift));

        for (int row = 0; row < heightShifted; row++)
        {
            final int length;

            if (pixelStride == 1 && outputStride == 1)
            {
                length = widthShifted;
                buffer.get(output.array(), channelOffset, length);
                channelOffset += length;
            }
            else
            {
                length = (widthShifted - 1) * pixelStride + 1;
                buffer.get(rowData, 0, length);

                for (int col = 0; col < widthShifted; col++)
                {
                    output.array()[channelOffset] = rowData[col * pixelStride];
                    channelOffset += outputStride;
                }
            }

            if (row < heightShifted - 1)
            {
                buffer.position(buffer.position() + rowStride - length);
            }
        }
    }

    return output;
}

将 android.media.Image (YUV_420_888) 转换为位图

Convert android.media.Image (YUV_420_888) to Bitmap

android

bitmap

android-camera

yuv