public static void TriangleWindowOscillatesCorrectly(float x, float expected)
{
IResampler sampler = KnownResamplers.Triangle;
float result = sampler.GetValue(x);
Assert.Equal(result, expected);
}
/// <summary>
/// Computes the weights to apply at each pixel when resizing.
/// </summary>
/// <param name="sampler">The <see cref="IResampler"/></param>
/// <param name="destinationSize">The destination size</param>
/// <param name="sourceSize">The source size</param>
/// <param name="memoryAllocator">The <see cref="MemoryAllocator"/> to use for buffer allocations</param>
/// <returns>The <see cref="KernelMap"/></returns>
public static KernelMap Calculate(
IResampler sampler,
int destinationSize,
int sourceSize,
MemoryAllocator memoryAllocator)
{
float ratio = (float)sourceSize / destinationSize;
float scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
float radius = MathF.Ceiling(scale * sampler.Radius);
var result = new KernelMap(memoryAllocator, destinationSize, radius);
for (int i = 0; i < destinationSize; i++)
{
float center = ((i + .5F) * ratio) - .5F;
// Keep inside bounds.
int left = (int)MathF.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)MathF.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
float sum = 0;
ResizeKernel ws = result.CreateKernel(i, left, right);
result.Kernels[i] = ws;
ref float weightsBaseRef = ref ws.GetStartReference();
for (int j = left; j <= right; j++)
{
float weight = sampler.GetValue((j - center) / scale);
sum += weight;
// weights[j - left] = weight:
Unsafe.Add(ref weightsBaseRef, j - left) = weight;
}
// Normalize, best to do it here rather than in the pixel loop later on.
if (sum > 0)
{
for (int w = 0; w < ws.Length; w++)
{
// weights[w] = weights[w] / sum:
ref float wRef = ref Unsafe.Add(ref weightsBaseRef, w);
wRef /= sum;
}
}
protected static void CalculateWeightsDown(int min, int max, int sourceMin, int sourceMax, float point, IResampler sampler, float scale, ref float weightsRef, int length)
{
float sum = 0;
// Downsampling weights requires more edge sampling plus normalization of the weights
for (int x = 0, i = min; i <= max; i++, x++)
{
int index = i;
if (index < sourceMin)
{
index = sourceMin;
}
if (index > sourceMax)
{
index = sourceMax;
}
float weight = sampler.GetValue((index - point) / scale);
sum += weight;
Unsafe.Add(ref weightsRef, x) = weight;
}
if (sum > 0)
{
for (int i = 0; i < length; i++)
{
ref float wRef = ref Unsafe.Add(ref weightsRef, i);
wRef = wRef / sum;
}
}
public static ReferenceKernelMap Calculate(IResampler sampler, int destinationSize, int sourceSize, bool normalize = true)
{
double ratio = (double)sourceSize / destinationSize;
double scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
TolerantMath tolerantMath = TolerantMath.Default;
double radius = tolerantMath.Ceiling(scale * sampler.Radius);
var result = new List <ReferenceKernel>();
for (int i = 0; i < destinationSize; i++)
{
double center = ((i + .5) * ratio) - .5;
// Keep inside bounds.
int left = (int)tolerantMath.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)tolerantMath.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
double sum = 0;
double[] values = new double[right - left + 1];
for (int j = left; j <= right; j++)
{
double weight = sampler.GetValue((float)((j - center) / scale));
sum += weight;
values[j - left] = weight;
}
if (sum > 0 && normalize)
{
for (int w = 0; w < values.Length; w++)
{
values[w] /= sum;
}
}
float[] floatVals = values.Select(v => (float)v).ToArray();
result.Add(new ReferenceKernel(left, floatVals));
}
return(new ReferenceKernelMap(result.ToArray()));
}
/// <summary>
/// Computes the weights to apply at each pixel when resizing.
/// </summary>
/// <param name="destinationSize">The destination section size.</param>
/// <param name="sourceSize">The source section size.</param>
/// <returns>
/// The <see cref="T:Weights[]"/>.
/// </returns>
protected Weights[] PrecomputeWeights(int destinationSize, int sourceSize)
{
float ratio = (float)sourceSize / destinationSize;
float scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
IResampler sampler = this.Sampler;
float radius = (float)Math.Ceiling(scale * sampler.Radius);
Weights[] result = new Weights[destinationSize];
for (int i = 0; i < destinationSize; i++)
{
float center = ((i + .5F) * ratio) - .5F;
// Keep inside bounds.
int left = (int)Math.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)Math.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
float sum = 0;
result[i] = new Weights();
Weight[] weights = new Weight[right - left + 1];
for (int j = left; j <= right; j++)
{
float weight = sampler.GetValue((j - center) / scale);
sum += weight;
weights[j - left] = new Weight(j, weight);
}
// Normalise, best to do it here rather than in the pixel loop later on.
if (sum > 0)
{
for (int w = 0; w < weights.Length; w++)
{
weights[w].Value = weights[w].Value / sum;
}
}
result[i].Values = weights;
}
return(result);
}
/// <summary>
/// Computes the weights to apply at each pixel when resizing.
/// </summary>
/// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations</param>
/// <param name="destinationSize">The destination size</param>
/// <param name="sourceSize">The source size</param>
/// <returns>The <see cref="WeightsBuffer"/></returns>
// TODO: Made internal to simplify experimenting with weights data. Make it private when finished figuring out how to optimize all the stuff!
internal WeightsBuffer PrecomputeWeights(MemoryManager memoryManager, int destinationSize, int sourceSize)
{
float ratio = (float)sourceSize / destinationSize;
float scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
IResampler sampler = this.Sampler;
float radius = MathF.Ceiling(scale * sampler.Radius);
var result = new WeightsBuffer(memoryManager, sourceSize, destinationSize);
for (int i = 0; i < destinationSize; i++)
{
float center = ((i + .5F) * ratio) - .5F;
// Keep inside bounds.
int left = (int)Math.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)Math.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
float sum = 0;
WeightsWindow ws = result.GetWeightsWindow(i, left, right);
result.Weights[i] = ws;
ref float weightsBaseRef = ref ws.GetStartReference();
for (int j = left; j <= right; j++)
{
float weight = sampler.GetValue((j - center) / scale);
sum += weight;
// weights[j - left] = weight:
Unsafe.Add(ref weightsBaseRef, j - left) = weight;
}
// Normalize, best to do it here rather than in the pixel loop later on.
if (sum > 0)
{
for (int w = 0; w < ws.Length; w++)
{
// weights[w] = weights[w] / sum:
ref float wRef = ref Unsafe.Add(ref weightsBaseRef, w);
wRef = wRef / sum;
}
}
/// <summary>
/// Computes the weights to apply at each pixel when resizing.
/// </summary>
/// <param name="destinationSize">The destination size</param>
/// <param name="sourceSize">The source size</param>
/// <returns>The <see cref="WeightsBuffer"/></returns>
// TODO: Made internal to simplify experimenting with weights data. Make it protected again when finished figuring out how to optimize all the stuff!
internal unsafe WeightsBuffer PrecomputeWeights(int destinationSize, int sourceSize)
{
float ratio = (float)sourceSize / destinationSize;
float scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
IResampler sampler = this.Sampler;
float radius = MathF.Ceiling(scale * sampler.Radius);
WeightsBuffer result = new WeightsBuffer(sourceSize, destinationSize);
for (int i = 0; i < destinationSize; i++)
{
float center = ((i + .5F) * ratio) - .5F;
// Keep inside bounds.
int left = (int)Math.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)Math.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
float sum = 0;
WeightsWindow ws = result.GetWeightsWindow(i, left, right);
result.Weights[i] = ws;
float *weights = ws.Ptr;
for (int j = left; j <= right; j++)
{
float weight = sampler.GetValue((j - center) / scale);
sum += weight;
weights[j - left] = weight;
}
// Normalise, best to do it here rather than in the pixel loop later on.
if (sum > 0)
{
for (int w = 0; w < ws.Length; w++)
{
weights[w] = weights[w] / sum;
}
}
}
return(result);
}
