public static void Convolve(this Convolution2D <float> convolution,
Image <float3> image, Image <float3> output)
{
var imageWidth = image.Width;
var outWidth = output.Width;
var outputBuffer = output.Buffer;
var stride = convolution.Stride;
var kernel = convolution.Kernel2D;
var pad = convolution.Padding;
var outputRow = 0;
for (var r = pad.y; r < image.Height - pad.y; r += stride.y)
{
var rowIndex = r * imageWidth;
var outRowIndex = outputRow * outWidth;
for (var c = pad.x; c < imageWidth - pad.x; c += stride.x)
{
var inIndex = rowIndex + c;
var outIndex = outRowIndex + c - pad.x;
outputBuffer[outIndex] = kernel.Accumulate(image, inIndex);
}
outputRow++;
}
}
public static void Convolve(this Convolution2D <float> convolution,
Image <byte> image, Image <float> output)
{
var outputBuffer = output.Buffer;
var imageWidth = image.Width;
var stride = convolution.Stride;
var kernel = convolution.Kernel2D;
var pad = convolution.Padding;
for (var r = pad.y; r < image.Height - pad.y; r += stride.y)
{
var rowIndex = r * imageWidth;
for (var c = pad.x; c < imageWidth - pad.x; c += stride.x)
{
var i = rowIndex + c;
outputBuffer[i] = kernel.Accumulate(image, i);
}
}
}
public static Padding GetSamePad <TInput, TConvolution>(Image <TInput> input,
Convolution2D <TConvolution> convolution)
where TInput : struct
where TConvolution : struct
{
var strides = convolution.Stride;
var kernel = convolution.Kernel2D;
var outHeight = (int)math.ceil((float)(input.Height - kernel.Height + 1) / strides.y);
var outWidth = (int)math.ceil((float)(input.Width - kernel.Width + 1) / strides.x);
var padding = new Padding();
var hDiff = input.Height - outHeight;
var wDiff = input.Width - outWidth;
if (hDiff % 2 == 0)
{
var halfDiff = hDiff / 2;
padding.left += halfDiff;
padding.right += halfDiff;
}
else
{
var halfDiff = (int)math.floor(hDiff / 2);
padding.left += halfDiff;
padding.right += halfDiff + 1;
}
if (wDiff % 2 == 0)
{
var halfDiff = wDiff / 2;
padding.top += halfDiff;
padding.bottom += halfDiff;
}
else
{
var halfDiff = (int)math.floor(wDiff / 2);
padding.top += halfDiff;
padding.bottom += halfDiff + 1;
}
return(padding);
}
public static Image <TImage> ConvolutionInput <TImage, TConvolution>(Image <TImage> input,
Convolution2D <TConvolution> convolution,
ConvolutionPadMode mode = ConvolutionPadMode.Same,
TImage constantValue = default(TImage),
Allocator allocator = Allocator.Persistent)
where TImage : struct
where TConvolution : struct
{
var output = default(Image <TImage>);
switch (mode)
{
case ConvolutionPadMode.Same:
var padding = GetSamePad(input, convolution);
output = Constant(input, padding, constantValue, allocator);
break;
case ConvolutionPadMode.Valid:
output = Constant(input, new Padding(0), constantValue, allocator);
break;
}
return(output);
}
