fix ugly chroma scaling

lib/reconstruct.lua

@@ -26,7 +26,8 @@ local function reconstruct_layer(model, x, block_size, offset)
    end
    return new_x
 end
-local function reconstruct(model, x, offset, block_size)
+local reconstruct = {}
+function reconstruct.image(model, x, offset, block_size)
    block_size = block_size or 128
    local output_size = block_size - offset * 2
    local h_blocks = math.floor(x:size(2) / output_size) +
@@ -54,5 +55,37 @@ local function reconstruct(model, x, offset, block_size)
 
    return output
 end
+function reconstruct.scale(model, scale, x, offset, block_size)
+   block_size = block_size or 128
+   local x_jinc = iproc.scale(x, x:size(3) * scale, x:size(2) * scale, "Jinc")
+   x = iproc.scale(x, x:size(3) * scale, x:size(2) * scale, "Box")
+
+   local output_size = block_size - offset * 2
+   local h_blocks = math.floor(x:size(2) / output_size) +
+      ((x:size(2) % output_size == 0 and 0) or 1)
+   local w_blocks = math.floor(x:size(3) / output_size) +
+      ((x:size(3) % output_size == 0 and 0) or 1)
+
+   local h = offset + h_blocks * output_size + offset
+   local w = offset + w_blocks * output_size + offset
+   local pad_h1 = offset
+   local pad_w1 = offset
+   local pad_h2 = (h - offset) - x:size(2)
+   local pad_w2 = (w - offset) - x:size(3)
+   local yuv_nn = image.rgb2yuv(iproc.padding(x, pad_w1, pad_w2, pad_h1, pad_h2))
+   local yuv_jinc = image.rgb2yuv(iproc.padding(x_jinc, pad_w1, pad_w2, pad_h1, pad_h2))
+   local y = reconstruct_layer(model, yuv_nn[1], block_size, offset)
+   y[torch.lt(y, 0)] = 0
+   y[torch.gt(y, 1)] = 1
+   yuv_jinc[1]:copy(y)
+   local output = image.yuv2rgb(image.crop(yuv_jinc,
+					   pad_w1, pad_h1,
+					   yuv_jinc:size(3) - pad_w2, yuv_jinc:size(2) - pad_h2))
+   output[torch.lt(output, 0)] = 0
+   output[torch.gt(output, 1)] = 1
+   collectgarbage()
+
+   return output
+end
 
 return reconstruct

train.lua

@@ -13,15 +13,11 @@ local pairwise_transform = require './lib/pairwise_transform'
 local image_loader = require './lib/image_loader'
 
 local function save_test_scale(model, rgb, file)
-   local input = iproc.scale(rgb,
-			     rgb:size(3) * settings.scale,
-			     rgb:size(2) * settings.scale)
-   local up = reconstruct(model, input, settings.block_offset)
-
+   local up = reconstruct.scale(model, settings.scale, rgb, settings.block_offset)
    image.save(file, up)
 end
 local function save_test_jpeg(model, rgb, file)
-   local im, count = reconstruct(model, rgb, settings.block_offset)
+   local im, count = reconstruct.image(model, rgb, settings.block_offset)
    image.save(file, im)
 end
 local function split_data(x, test_size)

waifu2x.lua

@@ -37,22 +37,20 @@ local function waifu2x()
       local model = torch.load(path.join(opt.model_dir,
 					 ("noise%d_model.t7"):format(opt.noise_level)), "ascii")
       model:evaluate()
-      new_x = reconstruct(model, x, BLOCK_OFFSET)
+      new_x = reconstruct.image(model, x, BLOCK_OFFSET)
    elseif opt.m == "scale" then
       local model = torch.load(path.join(opt.model_dir, "scale2.0x_model.t7"), "ascii")
       model:evaluate()
-      x = iproc.scale(x, x:size(3) * 2.0, x:size(2) * 2.0)
-      new_x = reconstruct(model, x, BLOCK_OFFSET)
+      new_x = reconstruct.scale(model, 2.0, x, BLOCK_OFFSET)
    elseif opt.m == "noise_scale" then
       local noise_model = torch.load(path.join(opt.model_dir,
 					       ("noise%d_model.t7"):format(opt.noise_level)), "ascii")
       local scale_model = torch.load(path.join(opt.model_dir, "scale2.0x_model.t7"), "ascii")
 
       noise_model:evaluate()
       scale_model:evaluate()
-      x = reconstruct(noise_model, x, BLOCK_OFFSET)
-      x = iproc.scale(x, x:size(3) * 2.0, x:size(2) * 2.0)
-      new_x = reconstruct(scale_model, x, BLOCK_OFFSET)
+      x = reconstruct.image(noise_model, x, BLOCK_OFFSET)
+      new_x = reconstruct.scale(scale_model, 2.0, x, BLOCK_OFFSET)
    else
       error("undefined method:" .. opt.method)
    end

web.lua

@@ -74,15 +74,13 @@ local function get_image(req)
 end
 
 local function apply_denoise1(x)
-   return reconstruct(noise1_model, x, BLOCK_OFFSET)
+   return reconstruct.image(noise1_model, x, BLOCK_OFFSET)
 end
 local function apply_denoise2(x)
-   return reconstruct(noise2_model, x, BLOCK_OFFSET)
+   return reconstruct.image(noise2_model, x, BLOCK_OFFSET)
 end
 local function apply_scale2x(x)
-   return reconstruct(scale20_model,
-		      iproc.scale(x, x:size(3) * 2.0, x:size(2) * 2.0),
-		      BLOCK_OFFSET)
+   return reconstruct.scale(scale20_model, 2.0, x, BLOCK_OFFSET)
 end
 local function cache_do(cache, x, func)
    if path.exists(cache) then