public void UpdateImages()
        {
            if (_mapData == null)
            {
                return;
            }

            int width  = _mapData.Width;
            int height = _mapData.Height;

            if (Bitmap == null ||
                Bitmap.PixelHeight != height ||
                Bitmap.PixelWidth != width)
            {
                Bitmap = new WriteableBitmap(width, height);
            }
            ZMax = new Thickness(0, height, 0, 0);

            if (ColorBar == null)
            {
                ColorBar = new WriteableBitmap(256, 1);
            }
            switch (ScalingTypeOptionVM.SelectedValue)
            {
            case ScalingType.Linear:
                for (int i = 0; i < _mapData.RawData.Length; i++)
                {
                    Bitmap.Pixels[i] = GetGrayscaleColor(_mapData.RawData[i], _MinValue, _MaxValue);
                }
                break;

            case ScalingType.Log:
            default:
                if (_MinValue <= 0.0)
                {
                    _MinValue = 10E-9;
                }
                if (_MaxValue <= 0.0)
                {
                    _MaxValue = 10E2;
                }
                for (int i = 0; i < _mapData.RawData.Length; i++)
                {
                    if (_mapData.RawData[i] >= 0)
                    {
                        Bitmap.Pixels[i] = GetGrayscaleColor(Math.Log10(_mapData.RawData[i]), Math.Log10(_MinValue), Math.Log10(_MaxValue));
                    }
                    else     // clamp to Log10(min) if the value goes negative
                    {
                        Bitmap.Pixels[i] = GetGrayscaleColor(Math.Log10(_MinValue), Math.Log10(_MinValue), Math.Log10(_MaxValue));
                    }
                }
                break;
            }
            Bitmap.Invalidate(); //refreshes the image

            for (int i = 0; i < ColorBar.PixelWidth; i++)
            {
                ColorBar.Pixels[i] = GetGrayscaleColor(i, 0, ColorBar.PixelWidth - 1);
            }
            ColorBar.Invalidate();

            YExpectationValue = _mapData.YExpectationValue;

            this.OnPropertyChanged("Bitmap");
            this.OnPropertyChanged("ColorBar");
            this.OnPropertyChanged("YExpectationValue");
        }