public static void ApplyColormap(Bitmap bmp, Colormap colormap)
{
switch (colormap)
{
case Colormap.grayscale:
new Colormaps.Grayscale().Apply(bmp);
break;
case Colormap.grayscaleInverted:
new Colormaps.GrayscaleInverted().Apply(bmp);
break;
case Colormap.vdBlue:
new Colormaps.VdBlues().Apply(bmp);
break;
case Colormap.vdGreen:
new Colormaps.VdGreens().Apply(bmp);
break;
case Colormap.viridis:
new Colormaps.Viridis().Apply(bmp);
break;
default:
throw new NotImplementedException();
}
}
public static Bitmap GetBitmap(
List <double[]> ffts,
Colormap cmap,
double intensity = 1,
bool dB = false,
double dBScale = 1,
bool roll = false,
int rollOffset = 0)
{
if (ffts.Count == 0)
{
throw new ArgumentException("This Spectrogram contains no FFTs (likely because no signal was added)");
}
int Width = ffts.Count;
int Height = ffts[0].Length;
Bitmap bmp = new Bitmap(Width, Height, PixelFormat.Format8bppIndexed);
cmap.Apply(bmp);
var lockRect = new Rectangle(0, 0, Width, Height);
BitmapData bitmapData = bmp.LockBits(lockRect, ImageLockMode.ReadOnly, bmp.PixelFormat);
int stride = bitmapData.Stride;
byte[] bytes = new byte[bitmapData.Stride * bmp.Height];
Parallel.For(0, Width, col =>
{
int sourceCol = col;
if (roll)
{
sourceCol += Width - rollOffset % Width;
if (sourceCol >= Width)
{
sourceCol -= Width;
}
}
for (int row = 0; row < Height; row++)
{
double value = ffts[sourceCol][row];
if (dB)
{
value = 20 * Math.Log10(value * dBScale + 1);
}
value *= intensity;
value = Math.Min(value, 255);
int bytePosition = (Height - 1 - row) * stride + col;
bytes[bytePosition] = (byte)value;
}
});
Marshal.Copy(bytes, 0, bitmapData.Scan0, bytes.Length);
bmp.UnlockBits(bitmapData);
return(bmp);
}
public void SetColormap(Colormap cmap)
{
this.cmap = cmap ?? this.cmap;
}
//For use in WPF
public static BitmapSource GetBitmapSource(IList <FftSharp.Complex[]> ffts, Colormap cmap, int sampleRate, double intensity = 1, bool dB = false, bool roll = false, int rollOffset = 0, double whiteNoiseMin = 0)
{
int resolution = sampleRate / ffts[0].Length;
int maxFreq = 7000;
int maxBin = maxFreq / resolution;
if (ffts.Count == 0)
{
throw new ArgumentException("This Spectrogram contains no FFTs (likely because no signal was added)");
}
int Width = ffts.Count;
int Height = Math.Min(maxBin, ffts[0].Length / 2); //No point in showing beyond nyquist frequency
var pixelFormat = System.Windows.Media.PixelFormats.Indexed8;
WriteableBitmap bit = new WriteableBitmap(Width, Height, 96, 96, pixelFormat, cmap.GetBitmapPalette());
//Lock the bits to make sure that no one can read them while we are writing to its memory
//Then we use a pointer to the backbuffer to write to the memory of the bitmap directly to avoid having to create an array and copy into it
bit.Lock();
unsafe
{
int stride = bit.BackBufferStride;
int bytesPerPixel = pixelFormat.BitsPerPixel / 8;
byte *bytes = (byte *)bit.BackBuffer; //Pointer to the raw color data of the bitmap
Parallel.For(0, Width, col =>
{
int sourceCol = col;
if (roll)
{
sourceCol += Width - rollOffset % Width;
if (sourceCol >= Width)
{
sourceCol -= Width;
}
}
for (int row = 0; row < Height; row++)
{
double value = ffts[sourceCol][row].Magnitude;
if (value <= whiteNoiseMin)
{
value = 0;
}
if (dB)
{
value = 20 * Math.Log10(value + 1);
}
value *= intensity;
value = Math.Min(value, 255);
int bytePosition = (Height - 1 - row) * stride + col * bytesPerPixel;
bytes[bytePosition] = (byte)value;
}
});
}
bit.AddDirtyRect(new Int32Rect(0, 0, Width, Height)); //Specifies the region of the bitmap that has changed so that it can update the image
bit.Unlock();
return(bit);
}
public Bitmap GetBitmap(Colormap cmap = null, double intensity = 1, bool dB = false)
{
cmap = cmap ?? Colormap.Viridis;
return(Image.GetBitmap(Ffts, cmap, intensity, dB));
}
