public void Convolve <TPixel>(
Vector2 transformedPoint,
int column,
ref float ySpanRef,
ref float xSpanRef,
Buffer2D <TPixel> sourcePixels,
Span <Vector4> targetRow)
where TPixel : struct, IPixel <TPixel>
{
// Clamp sampling pixel radial extents to the source image edges
Vector2 minXY = transformedPoint - this.extents;
Vector2 maxXY = transformedPoint + this.extents;
// left, top, right, bottom
var extents = new Vector4(
MathF.Ceiling(minXY.X - .5F),
MathF.Ceiling(minXY.Y - .5F),
MathF.Floor(maxXY.X + .5F),
MathF.Floor(maxXY.Y + .5F));
extents = Vector4.Clamp(extents, Vector4.Zero, this.maxSourceExtents);
int left = (int)extents.X;
int top = (int)extents.Y;
int right = (int)extents.Z;
int bottom = (int)extents.W;
if (left == right || top == bottom)
{
return;
}
this.CalculateWeights(top, bottom, transformedPoint.Y, ref ySpanRef);
this.CalculateWeights(left, right, transformedPoint.X, ref xSpanRef);
Vector4 sum = Vector4.Zero;
for (int kernelY = 0, y = top; y <= bottom; y++, kernelY++)
{
float yWeight = Unsafe.Add(ref ySpanRef, kernelY);
for (int kernelX = 0, x = left; x <= right; x++, kernelX++)
{
float xWeight = Unsafe.Add(ref xSpanRef, kernelX);
// Values are first premultiplied to prevent darkening of edge pixels.
var current = sourcePixels[x, y].ToVector4();
Vector4Utils.Premultiply(ref current);
sum += current * xWeight * yWeight;
}
}
// Reverse the premultiplication
Vector4Utils.UnPremultiply(ref sum);
targetRow[column] = sum;
}
public void UnPremultiply_VectorSpan(int length)
{
var rnd = new Random(42);
Vector4[] source = rnd.GenerateRandomVectorArray(length, 0, 1);
Vector4[] expected = source.Select(v => { Vector4Utils.UnPremultiply(ref v); return(v); }).ToArray();
Vector4Utils.UnPremultiply(source);
Assert.Equal(expected, source, new ApproximateFloatComparer(1e-6f));
}
internal static void ApplyBackwardConversionModifiers(Span <Vector4> vectors, PixelConversionModifiers modifiers)
{
if (modifiers.IsDefined(PixelConversionModifiers.Premultiply))
{
Vector4Utils.UnPremultiply(vectors);
}
if (modifiers.IsDefined(PixelConversionModifiers.SRgbCompand))
{
SRgbCompanding.Compress(vectors);
}
}
/// <inheritdoc/>
protected override void OnFrameApply(
ImageFrame <TPixel> source,
ImageFrame <TPixel> destination,
Rectangle sourceRectangle,
Configuration configuration)
{
int height = this.TargetDimensions.Height;
int width = this.TargetDimensions.Width;
Rectangle sourceBounds = source.Bounds();
var targetBounds = new Rectangle(0, 0, width, height);
// Since could potentially be resizing the canvas we might need to re-calculate the matrix
Matrix3x2 matrix = this.GetProcessingMatrix(sourceBounds, targetBounds);
// Convert from screen to world space.
Matrix3x2.Invert(matrix, out matrix);
if (this.Sampler is NearestNeighborResampler)
{
ParallelHelper.IterateRows(
targetBounds,
configuration,
rows =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
Span <TPixel> destRow = destination.GetPixelRowSpan(y);
for (int x = 0; x < width; x++)
{
var point = Point.Transform(new Point(x, y), matrix);
if (sourceBounds.Contains(point.X, point.Y))
{
destRow[x] = source[point.X, point.Y];
}
}
}
});
return;
}
int maxSourceX = source.Width - 1;
int maxSourceY = source.Height - 1;
(float radius, float scale, float ratio)xRadiusScale = this.GetSamplingRadius(source.Width, destination.Width);
(float radius, float scale, float ratio)yRadiusScale = this.GetSamplingRadius(source.Height, destination.Height);
float xScale = xRadiusScale.scale;
float yScale = yRadiusScale.scale;
var radius = new Vector2(xRadiusScale.radius, yRadiusScale.radius);
IResampler sampler = this.Sampler;
var maxSource = new Vector4(maxSourceX, maxSourceY, maxSourceX, maxSourceY);
int xLength = (int)MathF.Ceiling((radius.X * 2) + 2);
int yLength = (int)MathF.Ceiling((radius.Y * 2) + 2);
MemoryAllocator memoryAllocator = configuration.MemoryAllocator;
using (Buffer2D <float> yBuffer = memoryAllocator.Allocate2D <float>(yLength, height))
using (Buffer2D <float> xBuffer = memoryAllocator.Allocate2D <float>(xLength, height))
{
ParallelHelper.IterateRows(
targetBounds,
configuration,
rows =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
ref TPixel destRowRef = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
ref float ySpanRef = ref MemoryMarshal.GetReference(yBuffer.GetRowSpan(y));
ref float xSpanRef = ref MemoryMarshal.GetReference(xBuffer.GetRowSpan(y));
for (int x = 0; x < width; x++)
{
// Use the single precision position to calculate correct bounding pixels
// otherwise we get rogue pixels outside of the bounds.
var point = Vector2.Transform(new Vector2(x, y), matrix);
// Clamp sampling pixel radial extents to the source image edges
Vector2 maxXY = point + radius;
Vector2 minXY = point - radius;
// max, maxY, minX, minY
var extents = new Vector4(
MathF.Floor(maxXY.X + .5F),
MathF.Floor(maxXY.Y + .5F),
MathF.Ceiling(minXY.X - .5F),
MathF.Ceiling(minXY.Y - .5F));
int right = (int)extents.X;
int bottom = (int)extents.Y;
int left = (int)extents.Z;
int top = (int)extents.W;
extents = Vector4.Clamp(extents, Vector4.Zero, maxSource);
int maxX = (int)extents.X;
int maxY = (int)extents.Y;
int minX = (int)extents.Z;
int minY = (int)extents.W;
if (minX == maxX || minY == maxY)
{
continue;
}
// It appears these have to be calculated on-the-fly.
// Precalculating transformed weights would require prior knowledge of every transformed pixel location
// since they can be at sub-pixel positions on both axis.
// I've optimized where I can but am always open to suggestions.
if (yScale > 1 && xScale > 1)
{
CalculateWeightsDown(
top,
bottom,
minY,
maxY,
point.Y,
sampler,
yScale,
ref ySpanRef,
yLength);
CalculateWeightsDown(
left,
right,
minX,
maxX,
point.X,
sampler,
xScale,
ref xSpanRef,
xLength);
}
else
{
CalculateWeightsScaleUp(minY, maxY, point.Y, sampler, ref ySpanRef);
CalculateWeightsScaleUp(minX, maxX, point.X, sampler, ref xSpanRef);
}
// Now multiply the results against the offsets
Vector4 sum = Vector4.Zero;
for (int yy = 0, j = minY; j <= maxY; j++, yy++)
{
float yWeight = Unsafe.Add(ref ySpanRef, yy);
for (int xx = 0, i = minX; i <= maxX; i++, xx++)
{
float xWeight = Unsafe.Add(ref xSpanRef, xx);
// Values are first premultiplied to prevent darkening of edge pixels
var current = source[i, j].ToVector4();
Vector4Utils.Premultiply(ref current);
sum += current * xWeight * yWeight;
}
}
ref TPixel dest = ref Unsafe.Add(ref destRowRef, x);
// Reverse the premultiplication
Vector4Utils.UnPremultiply(ref sum);
dest.FromVector4(sum);
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source, ImageFrame <TPixel> destination, Rectangle sourceRectangle, Configuration configuration)
{
// Handle resize dimensions identical to the original
if (source.Width == destination.Width && source.Height == destination.Height && sourceRectangle == this.ResizeRectangle)
{
// The cloned will be blank here copy all the pixel data over
source.GetPixelSpan().CopyTo(destination.GetPixelSpan());
return;
}
int width = this.Width;
int height = this.Height;
int sourceX = sourceRectangle.X;
int sourceY = sourceRectangle.Y;
int startY = this.ResizeRectangle.Y;
int endY = this.ResizeRectangle.Bottom;
int startX = this.ResizeRectangle.X;
int endX = this.ResizeRectangle.Right;
int minX = Math.Max(0, startX);
int maxX = Math.Min(width, endX);
int minY = Math.Max(0, startY);
int maxY = Math.Min(height, endY);
if (this.Sampler is NearestNeighborResampler)
{
var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
// Scaling factors
float widthFactor = sourceRectangle.Width / (float)this.ResizeRectangle.Width;
float heightFactor = sourceRectangle.Height / (float)this.ResizeRectangle.Height;
ParallelHelper.IterateRows(
workingRect,
configuration,
rows =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
// Y coordinates of source points
Span <TPixel> sourceRow =
source.GetPixelRowSpan((int)(((y - startY) * heightFactor) + sourceY));
Span <TPixel> targetRow = destination.GetPixelRowSpan(y);
for (int x = minX; x < maxX; x++)
{
// X coordinates of source points
targetRow[x] = sourceRow[(int)(((x - startX) * widthFactor) + sourceX)];
}
}
});
return;
}
int sourceHeight = source.Height;
// Interpolate the image using the calculated weights.
// A 2-pass 1D algorithm appears to be faster than splitting a 1-pass 2D algorithm
// First process the columns. Since we are not using multiple threads startY and endY
// are the upper and lower bounds of the source rectangle.
using (Buffer2D <Vector4> firstPassPixelsTransposed = source.MemoryAllocator.Allocate2D <Vector4>(sourceHeight, width))
{
firstPassPixelsTransposed.MemorySource.Clear();
var processColsRect = new Rectangle(0, 0, source.Width, sourceRectangle.Bottom);
ParallelHelper.IterateRowsWithTempBuffer <Vector4>(
processColsRect,
configuration,
(rows, tempRowBuffer) =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
Span <TPixel> sourceRow = source.GetPixelRowSpan(y);
Span <Vector4> tempRowSpan = tempRowBuffer.Span;
PixelOperations <TPixel> .Instance.ToVector4(sourceRow, tempRowSpan, sourceRow.Length);
Vector4Utils.Premultiply(tempRowSpan);
ref Vector4 firstPassBaseRef = ref firstPassPixelsTransposed.Span[y];
if (this.Compand)
{
SRgbCompanding.Expand(tempRowSpan);
}
for (int x = minX; x < maxX; x++)
{
ResizeKernel window = this.horizontalKernelMap.Kernels[x - startX];
Unsafe.Add(ref firstPassBaseRef, x * sourceHeight) =
window.Convolve(tempRowSpan, sourceX);
}
}
});
var processRowsRect = Rectangle.FromLTRB(0, minY, width, maxY);
// Now process the rows.
ParallelHelper.IterateRowsWithTempBuffer <Vector4>(
processRowsRect,
configuration,
(rows, tempRowBuffer) =>
{
Span <Vector4> tempRowSpan = tempRowBuffer.Span;
for (int y = rows.Min; y < rows.Max; y++)
{
// Ensure offsets are normalized for cropping and padding.
ResizeKernel window = this.verticalKernelMap.Kernels[y - startY];
ref Vector4 tempRowBase = ref MemoryMarshal.GetReference(tempRowSpan);
for (int x = 0; x < width; x++)
{
Span <Vector4> firstPassColumn = firstPassPixelsTransposed.GetRowSpan(x);
// Destination color components
Unsafe.Add(ref tempRowBase, x) = window.Convolve(firstPassColumn, sourceY);
}
Vector4Utils.UnPremultiply(tempRowSpan);
if (this.Compand)
{
SRgbCompanding.Compress(tempRowSpan);
}
Span <TPixel> targetRowSpan = destination.GetPixelRowSpan(y);
PixelOperations <TPixel> .Instance.PackFromVector4(tempRowSpan, targetRowSpan, tempRowSpan.Length);
}
});
}
}