//detect blend direction
private void PreProcessCorners(Kernel4x4 ker)
{
_blendResult.Reset();
if ((ker.F == ker.G && ker.J == ker.K) || (ker.F == ker.J && ker.G == ker.K))
{
return;
}
var dist = _colorDistance;
const int weight = 4;
var jg = dist.DistYCbCr(ker.I, ker.F) + dist.DistYCbCr(ker.F, ker.C) + dist.DistYCbCr(ker.N, ker.K) + dist.DistYCbCr(ker.K, ker.H) + weight * dist.DistYCbCr(ker.J, ker.G);
var fk = dist.DistYCbCr(ker.E, ker.J) + dist.DistYCbCr(ker.J, ker.O) + dist.DistYCbCr(ker.B, ker.G) + dist.DistYCbCr(ker.G, ker.L) + weight * dist.DistYCbCr(ker.F, ker.K);
if (jg < fk)
{
var dominantGradient = _cfg.DominantDirectionThreshold * jg < fk;
if (ker.F != ker.G && ker.F != ker.J)
{
_blendResult.F = (char)(dominantGradient ? BlendType.Dominant : BlendType.Normal);
}
if (ker.K != ker.J && ker.K != ker.G)
{
_blendResult.K = (char)(dominantGradient ? BlendType.Dominant : BlendType.Normal);
}
}
else if (fk < jg)
{
var dominantGradient = _cfg.DominantDirectionThreshold * fk < jg;
if (ker.J != ker.F && ker.J != ker.K)
{
_blendResult.J = (char)(dominantGradient ? BlendType.Dominant : BlendType.Normal);
}
if (ker.G != ker.F && ker.G != ker.K)
{
_blendResult.G = (char)(dominantGradient ? BlendType.Dominant : BlendType.Normal);
}
}
}
//scaler policy: see "Scaler2x" reference implementation
private void ScaleImageImpl(int[] src, int[] trg, int srcWidth, int srcHeight, int yFirst, int yLast)
{
yFirst = Math.Max(yFirst, 0);
yLast = Math.Min(yLast, srcHeight);
if (yFirst >= yLast || srcWidth <= 0)
{
return;
}
var trgWidth = srcWidth * _scaler.Scale;
//temporary buffer for "on the fly preprocessing"
var preProcBuffer = new char[srcWidth];
var ker4 = new Kernel4x4();
//initialize preprocessing buffer for first row:
//detect upper left and right corner blending
//this cannot be optimized for adjacent processing
//stripes; we must not allow for a memory race condition!
if (yFirst > 0)
{
var y = yFirst - 1;
var sM1 = srcWidth * Math.Max(y - 1, 0);
var s0 = srcWidth * y; //center line
var sP1 = srcWidth * Math.Min(y + 1, srcHeight - 1);
var sP2 = srcWidth * Math.Min(y + 2, srcHeight - 1);
for (var x = 0; x < srcWidth; ++x)
{
var xM1 = Math.Max(x - 1, 0);
var xP1 = Math.Min(x + 1, srcWidth - 1);
var xP2 = Math.Min(x + 2, srcWidth - 1);
//read sequentially from memory as far as possible
ker4.A = src[sM1 + xM1];
ker4.B = src[sM1 + x];
ker4.C = src[sM1 + xP1];
ker4.D = src[sM1 + xP2];
ker4.E = src[s0 + xM1];
ker4.F = src[s0 + x];
ker4.G = src[s0 + xP1];
ker4.H = src[s0 + xP2];
ker4.I = src[sP1 + xM1];
ker4.J = src[sP1 + x];
ker4.K = src[sP1 + xP1];
ker4.L = src[sP1 + xP2];
ker4.M = src[sP2 + xM1];
ker4.N = src[sP2 + x];
ker4.O = src[sP2 + xP1];
ker4.P = src[sP2 + xP2];
PreProcessCorners(ker4); // writes to blendResult
/*
* preprocessing blend result:
* ---------
| F | G | //evalute corner between F, G, J, K
| ----|---| //input pixel is at position F
| J | K |
| ---------
*/
preProcBuffer[x] = preProcBuffer[x].SetTopR(_blendResult.J);
if (x + 1 < srcWidth)
{
preProcBuffer[x + 1] = preProcBuffer[x + 1].SetTopL(_blendResult.K);
}
}
}
_outputMatrix = new OutputMatrix(_scaler.Scale, trg, trgWidth);
var ker3 = new Kernel3x3();
for (var y = yFirst; y < yLast; ++y)
{
//consider MT "striped" access
var trgi = _scaler.Scale * y * trgWidth;
var sM1 = srcWidth * Math.Max(y - 1, 0);
var s0 = srcWidth * y; //center line
var sP1 = srcWidth * Math.Min(y + 1, srcHeight - 1);
var sP2 = srcWidth * Math.Min(y + 2, srcHeight - 1);
var blendXy1 = (char)0;
for (var x = 0; x < srcWidth; ++x, trgi += _scaler.Scale)
{
var xM1 = Math.Max(x - 1, 0);
var xP1 = Math.Min(x + 1, srcWidth - 1);
var xP2 = Math.Min(x + 2, srcWidth - 1);
//evaluate the four corners on bottom-right of current pixel
//blend_xy for current (x, y) position
//read sequentially from memory as far as possible
ker4.A = src[sM1 + xM1];
ker4.B = src[sM1 + x];
ker4.C = src[sM1 + xP1];
ker4.D = src[sM1 + xP2];
ker4.E = src[s0 + xM1];
ker4.F = src[s0 + x];
ker4.G = src[s0 + xP1];
ker4.H = src[s0 + xP2];
ker4.I = src[sP1 + xM1];
ker4.J = src[sP1 + x];
ker4.K = src[sP1 + xP1];
ker4.L = src[sP1 + xP2];
ker4.M = src[sP2 + xM1];
ker4.N = src[sP2 + x];
ker4.O = src[sP2 + xP1];
ker4.P = src[sP2 + xP2];
PreProcessCorners(ker4); // writes to blendResult
/*
* preprocessing blend result:
* ---------
| F | G | //evaluate corner between F, G, J, K
| ----|---| //current input pixel is at position F
| J | K |
| ---------
*/
//all four corners of (x, y) have been determined at
//this point due to processing sequence!
var blendXy = preProcBuffer[x].SetBottomR(_blendResult.F);
//set 2nd known corner for (x, y + 1)
blendXy1 = blendXy1.SetTopR(_blendResult.J);
//store on current buffer position for use on next row
preProcBuffer[x] = blendXy1;
//set 1st known corner for (x + 1, y + 1) and
//buffer for use on next column
blendXy1 = ((char)0).SetTopL(_blendResult.K);
if (x + 1 < srcWidth)
{
//set 3rd known corner for (x + 1, y)
preProcBuffer[x + 1] = preProcBuffer[x + 1].SetBottomL(_blendResult.G);
}
//fill block of size scale * scale with the given color
// //place *after* preprocessing step, to not overwrite the
// //results while processing the the last pixel!
FillBlock(trg, trgi, trgWidth, src[s0 + x], _scaler.Scale);
//blend four corners of current pixel
if (blendXy == 0)
{
continue;
}
const int a = 0, b = 1, c = 2, d = 3, e = 4, f = 5, g = 6, h = 7, i = 8;
//read sequentially from memory as far as possible
ker3._[a] = src[sM1 + xM1];
ker3._[b] = src[sM1 + x];
ker3._[c] = src[sM1 + xP1];
ker3._[d] = src[s0 + xM1];
ker3._[e] = src[s0 + x];
ker3._[f] = src[s0 + xP1];
ker3._[g] = src[sP1 + xM1];
ker3._[h] = src[sP1 + x];
ker3._[i] = src[sP1 + xP1];
ScalePixel(_scaler, (int)RotationDegree.R0, ker3, trgi, blendXy);
ScalePixel(_scaler, (int)RotationDegree.R90, ker3, trgi, blendXy);
ScalePixel(_scaler, (int)RotationDegree.R180, ker3, trgi, blendXy);
ScalePixel(_scaler, (int)RotationDegree.R270, ker3, trgi, blendXy);
}
}
}
