private void ShortFilter(ShortLookupTable lookup, Raster src, WritableRaster dst, int width, int height, int numBands)
{
int band;
int[] srcPix = null;
// Find the ref to the table and the offset
short[][] table = lookup.Table;
int offset = lookup.Offset;
int tidx;
int step = 1;
// Check if it is one lookup applied to all bands
if (table.Length == 1)
{
step = 0;
}
int x = 0;
int y = 0;
int index;
int maxShort = (1 << 16) - 1;
// Loop through the data
for (y = 0; y < height; y++)
{
tidx = 0;
for (band = 0; band < numBands; band++, tidx += step)
{
// Find data for this band, scanline
srcPix = src.GetSamples(0, y, width, 1, band, srcPix);
for (x = 0; x < width; x++)
{
index = srcPix[x] - offset;
if (index < 0 || index > maxShort)
{
throw new IllegalArgumentException("index out of range " + index + " x is " + x + "srcPix[x]=" + srcPix[x] + " offset=" + offset);
}
// Do the lookup
srcPix[x] = table[tidx][index];
}
// Put it back
dst.SetSamples(0, y, width, 1, band, srcPix);
}
}
}
/// <summary>
/// Rescales the pixel data in the source Raster.
/// If the destination Raster is null, a new Raster will be created.
/// The source and destination must have the same number of bands.
/// Otherwise, an IllegalArgumentException is thrown.
/// Note that the number of scaling factors/offsets in this object must
/// meet the restrictions stated in the class comments above.
/// Otherwise, an IllegalArgumentException is thrown. </summary>
/// <param name="src"> the <code>Raster</code> to be filtered </param>
/// <param name="dst"> the destination for the filtering operation
/// or <code>null</code> </param>
/// <returns> the filtered <code>WritableRaster</code>. </returns>
/// <exception cref="IllegalArgumentException"> if <code>src</code> and
/// <code>dst</code> do not have the same number of bands,
/// or if the number of scaling factors and offsets in this
/// <code>RescaleOp</code> do not meet the requirements
/// stated in the class comments. </exception>
public WritableRaster Filter(Raster src, WritableRaster dst)
{
int numBands = src.NumBands;
int width = src.Width;
int height = src.Height;
int[] srcPix = null;
int step = 0;
int tidx = 0;
// Create a new destination Raster, if needed
if (dst == null)
{
dst = CreateCompatibleDestRaster(src);
}
else if (height != dst.Height || width != dst.Width)
{
throw new IllegalArgumentException("Width or height of Rasters do not " + "match");
}
else if (numBands != dst.NumBands)
{
// Make sure that the number of bands are equal
throw new IllegalArgumentException("Number of bands in src " + numBands + " does not equal number of bands in dest " + dst.NumBands);
}
// Make sure that the arrays match
// Make sure that the low/high/constant arrays match
if (Length != 1 && Length != src.NumBands)
{
throw new IllegalArgumentException("Number of scaling constants " + "does not equal the number of" + " of bands in the src raster");
}
//
// Try for a native raster rescale first
//
if (ImagingLib.filter(this, src, dst) != null)
{
return(dst);
}
//
// Native raster rescale failed.
// Try to see if a lookup operation can be used
//
if (CanUseLookup(src, dst))
{
int srcNgray = (1 << SrcNbits);
int dstNgray = (1 << DstNbits);
if (dstNgray == 256)
{
ByteLookupTable lut = CreateByteLut(ScaleFactors, Offsets, numBands, srcNgray);
LookupOp op = new LookupOp(lut, Hints);
op.Filter(src, dst);
}
else
{
ShortLookupTable lut = CreateShortLut(ScaleFactors, Offsets, numBands, srcNgray);
LookupOp op = new LookupOp(lut, Hints);
op.Filter(src, dst);
}
}
else
{
//
// Fall back to the slow code
//
if (Length > 1)
{
step = 1;
}
int sminX = src.MinX;
int sY = src.MinY;
int dminX = dst.MinX;
int dY = dst.MinY;
int sX;
int dX;
//
// Determine bits per band to determine maxval for clamps.
// The min is assumed to be zero.
// REMIND: This must change if we ever support signed data types.
//
int nbits;
int[] dstMax = new int[numBands];
int[] dstMask = new int[numBands];
SampleModel dstSM = dst.SampleModel;
for (int z = 0; z < numBands; z++)
{
nbits = dstSM.GetSampleSize(z);
dstMax[z] = (1 << nbits) - 1;
dstMask[z] = ~(dstMax[z]);
}
int val;
for (int y = 0; y < height; y++, sY++, dY++)
{
dX = dminX;
sX = sminX;
for (int x = 0; x < width; x++, sX++, dX++)
{
// Get data for all bands at this x,y position
srcPix = src.GetPixel(sX, sY, srcPix);
tidx = 0;
for (int z = 0; z < numBands; z++, tidx += step)
{
val = (int)(srcPix[z] * ScaleFactors[tidx] + Offsets[tidx]);
// Clamp
if ((val & dstMask[z]) != 0)
{
if (val < 0)
{
val = 0;
}
else
{
val = dstMax[z];
}
}
srcPix[z] = val;
}
// Put it back for all bands
dst.SetPixel(dX, dY, srcPix);
}
}
}
return(dst);
}