/// <summary>
/// Applies histogram equalization to a given image.
/// </summary>
/// <param name="img"> The image of which to apply histogram equalization to </param>
/// <returns> The image with applied histogram equalization </returns>
public static UShortArrayAsImage ApplyHistogramEqualization(UShortArrayAsImage img)
// We found formula for making the histogram equalization here: https://epochabuse.com/histogram-equalization/
{
int[] histogram = MakeHistogram(img, out int blackPixelsCount);
double[] normalizedHistogram = MakeNormalizedHistogram(histogram, img.PixelArray.Length - blackPixelsCount);
double[] accumulativeHistogram = MakeAccumulativeHistogram(normalizedHistogram);
return(new UShortArrayAsImage(CalculateResult(img.PixelArray, accumulativeHistogram)));
}
/// <summary>
/// Resizes the given image to the given size.
/// </summary>
/// <param name="uShortArrayAsImageIn"> Image to be resized </param>
/// <param name="size"> Width and height of the resized image </param>
/// <returns> The resized image </returns>
public static UShortArrayAsImage ResizeImage(UShortArrayAsImage uShortArrayAsImageIn, int size)
{
var newImage = new ushort[size, size];
var image = uShortArrayAsImageIn.PixelArray;
for (int x = 0; x < size; x++)
{
for (int y = 0; y < size; y++)
{
newImage[y, x] = FindNearest(Map(x, 0, size, 0, image.GetLength(1)),
Map(y, 0, size, 0, image.GetLength(0)), image);
}
}
return(new UShortArrayAsImage(newImage));
}
/// <summary>
/// Normalizes, crops and resizes the given UShortArrayAsImage.
/// </summary>
/// <param name="image">The image to be normalized</param>
/// <param name="tumour">The position of the tumour</param>
/// <param name="size">The desired size of the image</param>
/// <returns>The normalized image as UShortArrayAsImage</returns>
public static UShortArrayAsImage GetNormalizedImage(UShortArrayAsImage image, Rectangle tumour, int size)
{
Rectangle squareTumour = new Rectangle();
//Resize the Rectangle
if (tumour.Width > tumour.Height)
{
squareTumour = new Rectangle(tumour.X, tumour.Y - (tumour.Width - tumour.Height) / 2, tumour.Width, tumour.Width);
}
else if (tumour.Width < tumour.Height || tumour.Width == tumour.Height)
{
squareTumour = new Rectangle(tumour.X - (tumour.Height - tumour.Width) / 2, tumour.Y, tumour.Height, tumour.Height);
}
return(ResizeImage(Crop(squareTumour, image), size));
}
/// <summary>
/// Creates a histogram based on the given image.
/// </summary>
/// <param name="img"> The image </param>
/// <param name="blackPixelsCount"> The amount of black pixels in the picture </param>
/// <returns> The image histogram </returns>
private static int[] MakeHistogram(UShortArrayAsImage img, out int blackPixelsCount)
{
int[] histogram = new int[UInt16.MaxValue + 1];
var pixelArray = img.PixelArray;
for (int i = 0; i < img.Height; i++)
{
for (int j = 0; j < img.Width; j++)
{
histogram[pixelArray[i, j]]++;
}
}
//Saving the amount of black pixels and setting the amount of black pixels to zero.
blackPixelsCount = histogram[0];
histogram[0] = 0;
return(histogram);
}
/// <summary>
/// Makes a crop with given location and size, out of an image.
/// </summary>
/// <param name="rectangle"> Location and size of the crop </param>
/// <param name="image"> Image to be cropped </param>
/// <returns> The cropped image </returns>
public static UShortArrayAsImage Crop(Rectangle rectangle, UShortArrayAsImage image)
{
ushort[,] result = new ushort[rectangle.Height, rectangle.Width];
ushort[,] current = image.PixelArray; // set here - lazy evaluation
for (int x = 0; x < rectangle.Width; x++)
{
if (rectangle.X + x < 0 || rectangle.X + x >= image.Width)
{
continue;
}
for (int y = 0; y < rectangle.Height; y++)
{
if (rectangle.Y + y < 0 || rectangle.Y + y >= image.Height)
{
continue;
}
result[y, x] = current[y + rectangle.Y, x + rectangle.X];
}
}
return(new UShortArrayAsImage(result));
}
