/// <summary>
/// Computes the parameters of the tiles.
/// </summary>
private void ComputeParametersOfTiles()
{
for (Int32 i = 0; i < _tileNumberVertically; ++i)
{
Int32 numberOfRowsInTile = (i < _tileNumberVertically - 1) ?
_numberOfPixelRowsOfNormalTile :
_numberOfPixelRowsOfNormalTile + Source.Raster.NumberOfRows % _tileNumberVertically;
for (Int32 j = 0; j < _tileNumberHorizontally; ++j)
{
Int32 numberOfColumnsInTile = (j < _tileNumberHorizontally - 1) ? _numberOfPixelColumnsOfNormalTile : _numberOfPixelColumnsOfNormalTile + Source.Raster.NumberOfColumns % _tileNumberHorizontally;
MaskedRaster tile = new MaskedRaster(null, Source.Raster, i * _numberOfPixelRowsOfNormalTile, j * _numberOfPixelColumnsOfNormalTile, numberOfRowsInTile, numberOfColumnsInTile);
_allTilesParameters[i, j] = new TileHistogramEqualizationParameters();
_allTilesParameters[i, j].CumulativeDistributionValues = new Double[Source.Raster.NumberOfBands][];
_allTilesParameters[i, j].CumulativeDistributionMinimums = new Double[Source.Raster.NumberOfBands];
_allTilesParameters[i, j].CumulativeDistributionMaximums = new Double[Source.Raster.NumberOfBands];
_allTilesParameters[i, j].RadiometricResolutionExponents = new Double[Source.Raster.NumberOfBands];
for (Int32 bandIndex = 0; bandIndex < Source.Raster.NumberOfBands; bandIndex++)
{
ComputeParametersOfActualTile(bandIndex, i, j, tile, _allTilesParameters[i, j]);
}
}
}
}
/// <summary>
/// Computes the transformed pixel value of a specified band based on the transformation function of a specified tile.
/// </summary>
/// <param name="value">The value of the specified pixel of the specified band.</param>
/// <param name="bandIndex">The band index.</param>
/// <param name="tileParameters">The actual tile's data.</param>
private Double PixelValueTransformation(UInt32 value, Int32 bandIndex, TileHistogramEqualizationParameters tileParameters)
{
return((tileParameters.CumulativeDistributionValues[bandIndex][value] - tileParameters.CumulativeDistributionMinimums[bandIndex]) / ((tileParameters.CumulativeDistributionMaximums[bandIndex] - tileParameters.CumulativeDistributionMinimums[bandIndex])) * tileParameters.RadiometricResolutionExponents[bandIndex]);
}
/// <summary>
/// Computes the parameters of the specified band of the actual tile.
/// </summary>
/// <param name="bandIndex">The band index.</param>
/// <param name="tileRowIndex">The row index.</param>
/// <param name="tileColumnIndex">The column index.</param>
/// <param name="actualTile">The actual tile.</param>
private void ComputeParametersOfActualTile(Int32 bandIndex, Int32 tileRowIndex, Int32 tileColumnIndex, MaskedRaster actualTile, TileHistogramEqualizationParameters actualTileParameters)
{
IReadOnlyList <Int32> histogram = actualTile.HistogramValues[bandIndex];
actualTileParameters.CumulativeDistributionValues[bandIndex] = new Double[histogram.Count];
// setting values
actualTileParameters.CumulativeDistributionValues[bandIndex][0] = Convert.ToDouble(histogram[0]) / (actualTile.NumberOfRows * actualTile.NumberOfColumns);
for (Int32 k = 1; k < histogram.Count; k++)
{
actualTileParameters.CumulativeDistributionValues[bandIndex][k] = actualTileParameters.CumulativeDistributionValues[bandIndex][k - 1] + Convert.ToDouble(histogram[k]) / (actualTile.NumberOfRows * actualTile.NumberOfColumns);
}
// setting minimum
Int32 minIndex = 0;
for (Int32 k = 0; k < histogram.Count; k++)
{
if (histogram[k] != 0)
{
minIndex = k;
break;
}
}
actualTileParameters.CumulativeDistributionMinimums[bandIndex] = actualTileParameters.CumulativeDistributionValues[bandIndex][minIndex];
// setting maximum
Int32 maxIndex = histogram.Count - 1;
for (Int32 k = histogram.Count - 1; k >= 0; k--)
{
if (histogram[k] != 0)
{
maxIndex = k;
break;
}
}
actualTileParameters.CumulativeDistributionMaximums[bandIndex] = actualTileParameters.CumulativeDistributionValues[bandIndex][maxIndex];
// exponent
actualTileParameters.RadiometricResolutionExponents[bandIndex] = Calculator.Pow(2, actualTile.RadiometricResolution);
}
