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Here's what I did (thanks Alexander):

This code goes into CameraBridgeViewBase.java in order to scale the bitmap to the size of the screen. The file is at:

[your path to the sdk]\OpenCV-2.4.4-android-sdk\sdk\java\src\org\opencv\android

protected void deliverAndDrawFrame(CvCameraViewFrame frame) {
    Mat modified;

    if (mListener != null) {
        modified = mListener.onCameraFrame(frame);
    } else {
        modified = frame.rgba();
    }

    boolean bmpValid = true;
    if (modified != null) {
        try {
            Utils.matToBitmap(modified, mCacheBitmap);
        } catch(Exception e) {
            Log.e(TAG, "Mat type: " + modified);
            Log.e(TAG, "Bitmap type: " + mCacheBitmap.getWidth() + "*" + mCacheBitmap.getHeight());
            Log.e(TAG, "Utils.matToBitmap() throws an exception: " + e.getMessage());
            bmpValid = false;
        }
    }

    if (bmpValid && mCacheBitmap != null) {
        Canvas canvas = getHolder().lockCanvas();
        if (canvas != null) {
            canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);


            /////////////////////////////////////////////////////
            ////// THIS IS THE CHANGED PART /////////////////////
            int width = mCacheBitmap.getWidth();
            int height = mCacheBitmap.getHeight();
            float scaleWidth = ((float) canvas.getWidth()) / width;
            float scaleHeight = ((float) canvas.getHeight()) / height;
            float fScale = Math.min(scaleHeight,  scaleWidth);
            // CREATE A MATRIX FOR THE MANIPULATION
            Matrix matrix = new Matrix();
            // RESIZE THE BITMAP
            matrix.postScale(fScale, fScale);

            /////////////////////////////////////////////////////

            // RECREATE THE NEW BITMAP
            Bitmap resizedBitmap = Bitmap.createBitmap(mCacheBitmap, 0, 0, width, height, matrix, false);

            canvas.drawBitmap(resizedBitmap, (canvas.getWidth() - resizedBitmap.getWidth()) / 2, (canvas.getHeight() - resizedBitmap.getHeight()) / 2, null);
            if (mFpsMeter != null) {
                mFpsMeter.measure();
                mFpsMeter.draw(canvas, 20, 30);
            }
            getHolder().unlockCanvasAndPost(canvas);
        }
    }
}

So I now have an image which looks like this:

Which was what I wanted.