added two generic upsamplers/resamplers modules

1 files changed, 55 insertions, 0 deletions

diff --git a/SpatialReSampling.lua b/SpatialReSampling.lua
new file mode 100644
index 0000000..20c9985
--- /dev/null
+++ b/SpatialReSampling.lua
@@ -0,0 +1,55 @@
+local SpatialReSampling, parent = torch.class('nn.SpatialReSampling', 'nn.Module')
+
+local help_desc =
+[[Applies a 2D re-sampling over an input image composed of
+several input planes. The input tensor in forward(input) is 
+expected to be a 3D tensor (width x height x nInputPlane). 
+The number of output planes will be the same as the nb of input
+planes.
+
+The re-sampling is done using bilinear interpolation. For a
+simple nearest-neihbor upsampling, use nn.SpatialUpSampling(),
+and for a simple average-based down-sampling, use 
+nn.SpatialDownSampling().
+
+If the input image is a 3D tensor nInputPlane x height x width,
+the output image size will be nInputPlane x oheight x owidth where
+owidth and oheight are given to the constructor.
+
+Instead of owidth & oheight, one can provide rwidth & rheight, 
+such that owidth = iwidth*rwidth & oheight = iheight*rheight. ]]
+
+function SpatialReSampling:__init(...)
+   parent.__init(self)
+   xlua.unpack_class(
+      self, {...}, 'nn.SpatialReSampling', help_desc,
+      {arg='owidth', type='number', help='output width'},
+      {arg='oheight', type='number', help='output height'},
+      {arg='rwidth', type='number', help='ratio: owidth/iwidth'},
+      {arg='rheight', type='number', help='ratio: oheight/iheight'}
+   )
+end
+
+function SpatialReSampling:forward(input)
+   self.oheight = self.oheight or self.rheight*input:size(2)
+   self.owidth = self.owidth or self.rwidth*input:size(3)
+   input.nn.SpatialReSampling_forward(self, input)
+   return self.output
+end
+
+function SpatialReSampling:backward(input, gradOutput)
+   input.nn.SpatialReSampling_backward(self, input, gradOutput)
+   return self.gradInput
+end
+
+function SpatialReSampling:write(file)
+   parent.write(self, file)
+   file:writeInt(self.owidth)
+   file:writeInt(self.oheight)
+end
+
+function SpatialReSampling:read(file)
+   parent.read(self, file)
+   self.owidth = file:readInt()
+   self.oheight = file:readInt()
+end