diff --git a/src/ImageSharp/Processing/Processors/Convolution/Parameters/BokehBlurKernelDataProvider.cs b/src/ImageSharp/Processing/Processors/Convolution/Parameters/BokehBlurKernelDataProvider.cs new file mode 100644 index 0000000000..1ff4c9ac6d --- /dev/null +++ b/src/ImageSharp/Processing/Processors/Convolution/Parameters/BokehBlurKernelDataProvider.cs @@ -0,0 +1,225 @@ +using System; +using System.Collections.Concurrent; +using System.Collections.Generic; +using System.Numerics; +using System.Runtime.CompilerServices; +using System.Runtime.InteropServices; + +namespace SixLabors.ImageSharp.Processing.Processors.Convolution.Parameters +{ + /// + /// Provides parameters to be used in the . + /// + internal static class BokehBlurKernelDataProvider + { + /// + /// The mapping of initialized complex kernels and parameters, to speed up the initialization of new instances + /// + private static readonly ConcurrentDictionary Cache = new ConcurrentDictionary(); + + /// + /// Gets the kernel scales to adjust the component values in each kernel + /// + private static IReadOnlyList KernelScales { get; } = new[] { 1.4f, 1.2f, 1.2f, 1.2f, 1.2f, 1.2f }; + + /// + /// Gets the available bokeh blur kernel parameters + /// + private static IReadOnlyList KernelComponents { get; } = new[] + { + // 1 component + new[] { new Vector4(0.862325f, 1.624835f, 0.767583f, 1.862321f) }, + + // 2 components + new[] + { + new Vector4(0.886528f, 5.268909f, 0.411259f, -0.548794f), + new Vector4(1.960518f, 1.558213f, 0.513282f, 4.56111f) + }, + + // 3 components + new[] + { + new Vector4(2.17649f, 5.043495f, 1.621035f, -2.105439f), + new Vector4(1.019306f, 9.027613f, -0.28086f, -0.162882f), + new Vector4(2.81511f, 1.597273f, -0.366471f, 10.300301f) + }, + + // 4 components + new[] + { + new Vector4(4.338459f, 1.553635f, -5.767909f, 46.164397f), + new Vector4(3.839993f, 4.693183f, 9.795391f, -15.227561f), + new Vector4(2.791880f, 8.178137f, -3.048324f, 0.302959f), + new Vector4(1.342190f, 12.328289f, 0.010001f, 0.244650f) + }, + + // 5 components + new[] + { + new Vector4(4.892608f, 1.685979f, -22.356787f, 85.91246f), + new Vector4(4.71187f, 4.998496f, 35.918936f, -28.875618f), + new Vector4(4.052795f, 8.244168f, -13.212253f, -1.578428f), + new Vector4(2.929212f, 11.900859f, 0.507991f, 1.816328f), + new Vector4(1.512961f, 16.116382f, 0.138051f, -0.01f) + }, + + // 6 components + new[] + { + new Vector4(5.143778f, 2.079813f, -82.326596f, 111.231024f), + new Vector4(5.612426f, 6.153387f, 113.878661f, 58.004879f), + new Vector4(5.982921f, 9.802895f, 39.479083f, -162.028887f), + new Vector4(6.505167f, 11.059237f, -71.286026f, 95.027069f), + new Vector4(3.869579f, 14.81052f, 1.405746f, -3.704914f), + new Vector4(2.201904f, 19.032909f, -0.152784f, -0.107988f) + } + }; + + /// + /// Gets the bokeh blur kernel data for the specified parameters. + /// + /// The value representing the size of the area to sample. + /// The size of each kernel to compute. + /// The number of components to use to approximate the original 2D bokeh blur convolution kernel. + /// A instance with the kernel data for the current parameters. + public static BokehBlurKernelData GetBokehBlurKernelData( + int radius, + int kernelSize, + int componentsCount) + { + // Reuse the initialized values from the cache, if possible + var parameters = new BokehBlurParameters(radius, componentsCount); + if (!Cache.TryGetValue(parameters, out BokehBlurKernelData info)) + { + // Initialize the complex kernels and parameters with the current arguments + (Vector4[] kernelParameters, float kernelsScale) = GetParameters(componentsCount); + Complex64[][] kernels = CreateComplexKernels(kernelParameters, radius, kernelSize, kernelsScale); + NormalizeKernels(kernels, kernelParameters); + + // Store them in the cache for future use + info = new BokehBlurKernelData(kernelParameters, kernelsScale, kernels); + Cache.TryAdd(parameters, info); + } + + return info; + } + + /// + /// Gets the kernel parameters and scaling factor for the current count value in the current instance + /// + private static (Vector4[] Parameters, float Scale) GetParameters(int componentsCount) + { + // Prepare the kernel components + int index = Math.Max(0, Math.Min(componentsCount - 1, KernelComponents.Count)); + + return (KernelComponents[index], KernelScales[index]); + } + + /// + /// Creates the collection of complex 1D kernels with the specified parameters + /// + /// The parameters to use to normalize the kernels + /// The value representing the size of the area to sample. + /// The size of each kernel to compute. + /// The scale factor for each kernel. + private static Complex64[][] CreateComplexKernels( + Vector4[] kernelParameters, + int radius, + int kernelSize, + float kernelsScale) + { + var kernels = new Complex64[kernelParameters.Length][]; + ref Vector4 baseRef = ref MemoryMarshal.GetReference(kernelParameters.AsSpan()); + for (int i = 0; i < kernelParameters.Length; i++) + { + ref Vector4 paramsRef = ref Unsafe.Add(ref baseRef, i); + kernels[i] = CreateComplex1DKernel(radius, kernelSize, kernelsScale, paramsRef.X, paramsRef.Y); + } + + return kernels; + } + + /// + /// Creates a complex 1D kernel with the specified parameters + /// + /// The value representing the size of the area to sample. + /// The size of each kernel to compute. + /// The scale factor for each kernel. + /// The exponential parameter for each complex component + /// The angle component for each complex component + private static Complex64[] CreateComplex1DKernel( + int radius, + int kernelSize, + float kernelsScale, + float a, + float b) + { + var kernel = new Complex64[kernelSize]; + ref Complex64 baseRef = ref MemoryMarshal.GetReference(kernel.AsSpan()); + int r = radius, n = -r; + + for (int i = 0; i < kernelSize; i++, n++) + { + // Incrementally compute the range values + float value = n * kernelsScale * (1f / r); + value *= value; + + // Fill in the complex kernel values + Unsafe.Add(ref baseRef, i) = new Complex64( + MathF.Exp(-a * value) * MathF.Cos(b * value), + MathF.Exp(-a * value) * MathF.Sin(b * value)); + } + + return kernel; + } + + /// + /// Normalizes the kernels with respect to A * real + B * imaginary + /// + /// The current convolution kernels to normalize + /// The parameters to use to normalize the kernels + private static void NormalizeKernels(Complex64[][] kernels, Vector4[] kernelParameters) + { + // Calculate the complex weighted sum + float total = 0; + Span kernelsSpan = kernels.AsSpan(); + ref Complex64[] baseKernelsRef = ref MemoryMarshal.GetReference(kernelsSpan); + ref Vector4 baseParamsRef = ref MemoryMarshal.GetReference(kernelParameters.AsSpan()); + + for (int i = 0; i < kernelParameters.Length; i++) + { + ref Complex64[] kernelRef = ref Unsafe.Add(ref baseKernelsRef, i); + int length = kernelRef.Length; + ref Complex64 valueRef = ref kernelRef[0]; + ref Vector4 paramsRef = ref Unsafe.Add(ref baseParamsRef, i); + + for (int j = 0; j < length; j++) + { + for (int k = 0; k < length; k++) + { + ref Complex64 jRef = ref Unsafe.Add(ref valueRef, j); + ref Complex64 kRef = ref Unsafe.Add(ref valueRef, k); + total += + (paramsRef.Z * ((jRef.Real * kRef.Real) - (jRef.Imaginary * kRef.Imaginary))) + + (paramsRef.W * ((jRef.Real * kRef.Imaginary) + (jRef.Imaginary * kRef.Real))); + } + } + } + + // Normalize the kernels + float scalar = 1f / MathF.Sqrt(total); + for (int i = 0; i < kernelsSpan.Length; i++) + { + ref Complex64[] kernelsRef = ref Unsafe.Add(ref baseKernelsRef, i); + int length = kernelsRef.Length; + ref Complex64 valueRef = ref kernelsRef[0]; + + for (int j = 0; j < length; j++) + { + Unsafe.Add(ref valueRef, j) *= scalar; + } + } + } + } +}