将android.media.Image(YUV_420_888)转换为Bitmap

问题描述 投票:11回答:3

我正在尝试使用camera2 api实现相机预览图像数据处理,如下所示:Camera preview image data processing with Android L and Camera2 API

我使用onImageAvailableListener成功接收回调,但是为了将来的处理,我需要从YUV_420_888 android.media.Image获取位图。我搜索了类似的问题,但没有一个帮助。

你能否建议我如何将android.media.Image(YUV_420_888)转换为Bitmap,或者有更好的方法来监听预览帧?

android bitmap android-camera yuv
3个回答
3
投票

我写了一些关于这个的代码,它是YUV数据预览并将其转换为JPEG数据,我可以用它来保存为位图,byte []或其他。(你可以看到类“Allocation”)。 SDK文档说: “使用android.renderscript进行高效的YUV处理:创建一个支持YUV类型的RenderScript分配,IO_INPUT标志和getOutputSizes(Allocation.class)返回的一个大小,然后使用getSurface()获取Surface。” 这是代码,希望它能帮到你:https://github.com/pinguo-yuyidong/Camera2/blob/master/camera2/src/main/rs/yuv2rgb.rs


6
投票

有关更简单的解决方案,请参阅此处的实施:

Conversion YUV 420_888 to Bitmap (full code)

该函数将media.image作为输入,并基于y,u和v平面创建三个RenderScript分配。它遵循YUV_420_888逻辑,如此Wikipedia插图中所示。

enter image description here

但是,这里我们有Y,U和V通道的三个独立的图像平面,因此我把它们作为三个字节[],即U8分配。 y分配具有大小宽度*高度字节,而u分配和v分配每个具有大小宽度*高度/ 4字节,反映了每个u字节覆盖4个像素(每个v字节同样)的事实。


1
投票

您可以使用内置的Renderscript内在函数ScriptIntrinsicYuvToRGB来完成此操作。代码取自Camera2 api Imageformat.yuv_420_888 results on rotated image

@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;
}
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