错误的像素化图像 - 自定义 android 相机

Question

我制作了自己的定制相机。这给了我糟糕的像素化图像，我不知道为什么。我可能使用质量为 100 的 JPEG 压缩。这是我得到的图像 Camera picture

这是我的代码：

public class CameraSurfaceView extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Context mContext;
private Camera.Parameters parameters;
private byte[] mBuffer;

public CameraSurfaceView(Context context) {
    super(context);
    mContext = context;
    mHolder = getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
    // The Surface has been created, now tell the camera where to draw the preview.
    try {
        if (CameraConfigurationUtils.mCameraInstance != null) {
            CameraConfigurationUtils.mCameraInstance.setDisplayOrientation(90);
            CameraConfigurationUtils.mCameraInstance.setPreviewDisplay(holder);
            parameters = CameraConfigurationUtils.mCameraInstance.getParameters();
            if (android.os.Build.VERSION.SDK_INT >= 14) {
                CameraConfigurationUtils.setFocus(parameters, true, true, false);
            } else {
                CameraConfigurationUtils.setFocus(parameters, true, true, true);
            }
            WindowManager manager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
            Display display = manager.getDefaultDisplay();
            Point theScreenResolution = new Point();
            theScreenResolution.set(display.getHeight(), display.getWidth());
            CameraConfigurationUtils.findBestPreviewSizeValue(parameters, theScreenResolution);
            CameraConfigurationUtils.mCameraInstance.setParameters(parameters);
            updateBufferSize();
            CameraConfigurationUtils.mCameraInstance.addCallbackBuffer(mBuffer);
            CameraConfigurationUtils.mCameraInstance.setPreviewCallbackWithBuffer(new Camera.PreviewCallback() {
                public synchronized void onPreviewFrame(byte[] data, Camera c) {
                    if (CameraConfigurationUtils.mCameraInstance != null) {
                        CameraConfigurationUtils.mCameraInstance.addCallbackBuffer(mBuffer);
                    }
                }
            });
            CameraConfigurationUtils.startPreview(mContext);
        }
    } catch (IOException e) {
        e.printStackTrace();
        CameraConfigurationUtils.releaseCamera();
    }

}

public void surfaceDestroyed(SurfaceHolder holder) {
    mHolder.removeCallback(this);
    CameraConfigurationUtils.stopPreview();
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    if (mHolder.getSurface() == null) {
        return;
    }
    try {
        CameraConfigurationUtils.mCameraInstance.setPreviewDisplay(mHolder);
        CameraConfigurationUtils.startPreview(mContext);
    } catch (Exception e) {
        CameraConfigurationUtils.releaseCamera();
    }
}

public byte[] getPic(int x, int y, int width, int height) {
    System.gc();
    Camera.Size s = parameters.getPreviewSize();
    YuvImage yuvimage = new YuvImage(mBuffer, ImageFormat.NV21, s.width, s.height, null);
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    yuvimage.compressToJpeg(new Rect(x, y, width, height), 100, outStream); // make JPG

    yuvimage = null;
    System.gc();
    return outStream.toByteArray();
}

private void updateBufferSize() {
    mBuffer = null;
    System.gc();
    // prepare a buffer for copying preview data to
    int h = parameters.getPreviewSize().height;
    int w = parameters.getPreviewSize().width;
    int bitsPerPixel = ImageFormat.getBitsPerPixel(parameters.getPreviewFormat());
    mBuffer = new byte[w * h * bitsPerPixel / 8];
    //Log.i("surfaceCreated", "buffer length is " + mBuffer.length + " bytes");
}

}

我做错了什么？

Answer 1

您的图片示例看起来就像来自相机的常规低分辨率预览图像，但我可以看到在高分辨率屏幕上它会显示像素化。我相信你的问题在于这部分代码：

CameraConfigurationUtils.findBestPreviewSizeValue(parameters, theScreenResolution);
CameraConfigurationUtils.mCameraInstance.setParameters(parameters);

您似乎只是在计算最佳预览尺寸，该尺寸已返回给您，但您并未将其设置为实际预览尺寸。像这样尝试：

Point bestPreviewSize = CameraConfigurationUtils.findBestPreviewSizeValue(parameters, theScreenResolution);
parameters.setPreviewSize(bestPreviewSize.x, bestPreviewSize.y);
CameraConfigurationUtils.mCameraInstance.setParameters(parameters);

另一件事是，如果您打算拍摄高分辨率照片，则不应使用 getPic() 方法，因为它只是获取 jpeg 格式的预览帧，这是较低分辨率的图像.为此，您应该查看 Camera#takePicture method。

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