Android YuvImage class format incorrect?

It's well documented that Android's camera preview data is returned back in NV21 (YUV 420). 2.2 added a YuvImage class for decoding the data. The problem I've encountered is that the YuvImage class data appears corrupt or incorrect. I used the Renderscript Sample app called HelloCompute which transforms a Bitm开发者_如何学Cap into a mono-chrome Bitmap. I used two methods for decoding the Preview data into a Bitmap and passing it as input to the Renderscript:

Method 1 - Android YuvImage Class:

YuvImage preview = new YuvImage(data, ImageFormat.NV21, width, height, null);

ByteArrayOutputStream mJpegOutput = new ByteArrayOutputStream(data.length); 

preview.compressToJpeg(new Rect(0, 0, width, height), 100, mJpegOutput);
mBitmapIn = BitmapFactory.decodeByteArray( mJpegOutput.toByteArray(), 0, mJpegOutput.size());

// pass mBitmapIn to RS

Method 2 - Posted Decoder Method: As posted over here by David Pearlman

// work around for Yuv format </p>
mBitmapIn = Bitmap.createBitmap(
      ImageUtil.decodeYUV420SP(data, width, height),
      width, 
      height, 
      Bitmap.Config.ARGB_8888);

// pass mBitmapIn to RS

When the image is processed by the Renderscript and displayed Method 1 is very grainy and not mono-chrome, while Method 2 produces the expected output, a mono-chrome image of the preview frame. Am I doing something wrong or is the YuvImage class not usable? I'm testing this on a Xoom running 3.1.

Furthermore, I displayed the bitmaps produced by both methods on screen prior to passing to the RS. The bitmap from Method 1 has noticeable differences in lighting (I suspected this was due to the JPeg compression), while Method 2's bitmap is identical to the Preview Frame.

There is no justification for using Jpeg encode/decode just to convert a YUV image to a grayscale bitmap (I believe you want grayscale, not monochrome b/w bitmap after all). You can find many code samples that produce the result you need. You may use this one: Converting preview frame to bitmap.