lua torch rgb <=> yuv

rgbyuv.lua

local function rgbToYuv(rgbTensor)
  local r,g,b = rgbTensor[1],rgbTensor[2],rgbTensor[3]
  local yuvTensor = rgbTensor:clone()
  yuvTensor[1] = torch.mul(r, 0.299) + torch.mul(g, 0.587) + torch.mul(b, 0.114)
  yuvTensor[2] = torch.mul(b - yuvTensor[1], 0.492)
  yuvTensor[3] = torch.mul(r - yuvTensor[1], 0.877)
  return yuvTensor
end

local function yuvToRgb(yuvTensor)
  local y,u,v = yuvTensor[1],yuvTensor[2],yuvTensor[3]
  local rgbTensor = yuvTensor:clone()
  rgbTensor[1] = y + torch.mul(v, 1.13983)
  rgbTensor[2] = y + torch.mul(u, -0.39465) + torch.mul(v, -0.58060)
  rgbTensor[3] = y + torch.mul(u, 2.03211)
  return rgbTensor
end