96 lines
2.5 KiB
Lua
96 lines
2.5 KiB
Lua
require 'image'
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local iproc = require 'iproc'
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local data_augmentation = {}
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local function pcacov(x)
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local mean = torch.mean(x, 1)
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local xm = x - torch.ger(torch.ones(x:size(1)), mean:squeeze())
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local c = torch.mm(xm:t(), xm)
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c:div(x:size(1) - 1)
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local ce, cv = torch.symeig(c, 'V')
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return ce, cv
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end
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function data_augmentation.color_noise(src, factor)
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factor = factor or 0.1
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local src, conversion = iproc.byte2float(src)
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local src_t = src:reshape(src:size(1), src:nElement() / src:size(1)):t():contiguous()
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local ce, cv = pcacov(src_t)
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local color_scale = torch.Tensor(3):uniform(1 / (1 + factor), 1 + factor)
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pca_space = torch.mm(src_t, cv):t():contiguous()
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for i = 1, 3 do
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pca_space[i]:mul(color_scale[i])
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end
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local dest = torch.mm(pca_space:t(), cv:t()):t():contiguous():resizeAs(src)
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dest[torch.lt(dest, 0.0)] = 0.0
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dest[torch.gt(dest, 1.0)] = 1.0
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if conversion then
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dest = iproc.float2byte(dest)
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end
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return dest
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end
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function data_augmentation.shift_1px(src)
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-- reducing the even/odd issue in nearest neighbor scaler.
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local direction = torch.random(1, 4)
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local x_shift = 0
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local y_shift = 0
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if direction == 1 then
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x_shift = 1
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y_shift = 0
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elseif direction == 2 then
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x_shift = 0
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y_shift = 1
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elseif direction == 3 then
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x_shift = 1
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y_shift = 1
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elseif flip == 4 then
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x_shift = 0
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y_shift = 0
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end
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local w = src:size(3) - x_shift
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local h = src:size(2) - y_shift
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w = w - (w % 4)
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h = h - (h % 4)
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local dest = iproc.crop(src, x_shift, y_shift, x_shift + w, y_shift + h)
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return dest
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end
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function data_augmentation.flip(src)
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local flip = torch.random(1, 4)
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local src, conversion = iproc.byte2float(src)
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local dest
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src = src:contiguous()
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if flip == 1 then
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dest = image.hflip(src)
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elseif flip == 2 then
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dest = image.vflip(src)
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elseif flip == 3 then
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dest = image.hflip(image.vflip(src))
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elseif flip == 4 then
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dest = src
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end
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if conversion then
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dest = iproc.float2byte(dest)
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end
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return dest
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end
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function data_augmentation.overlay(src, p)
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p = p or 0.25
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if torch.uniform() < p then
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local r = torch.uniform(0.2, 0.8)
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local src, conversion = iproc.byte2float(src)
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src = src:contiguous()
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local flip = data_augmentation.flip(src)
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flip:mul(r):add(src * (1.0 - r))
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if conversion then
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flip = iproc.float2byte(flip)
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end
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return flip
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else
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return src
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end
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end
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return data_augmentation
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