fix display_id bug

test.lua

@@ -23,9 +23,8 @@ else
   print ("CPU Mode")
 end
 
--- visualizer
+-- setup visualization
 visualizer = require 'util/visualizer'
-print(visualizer.save_images)
 
 function TableConcat(t1,t2)
   for i=1,#t2 do

train.lua

@@ -14,10 +14,7 @@ options = require 'options'
 opt = options.parse_options('train')
 
 -- setup visualization
-if opt.display_id > 0 then
-  disp = require 'display'
-  visualizer = require 'util/visualizer'
-end
+visualizer = require 'util/visualizer'
 
 -- initialize torch GPU/CPU mode
 if opt.gpu > 0 then

util/visualizer.lua

@@ -5,10 +5,15 @@
 local visualizer = {}
 
 require 'torch'
-disp = require 'display'
+disp = nil
+
+if opt.display_id > 0 then -- [hack]: assume that opt already existed
+  disp = require 'display'
+end
 util = require 'util/util'
 require 'image'
 
+-- function visualizer
 function visualizer.disp_image(img_data, win_size, display_id, title)
   local tensortype = torch.getdefaulttensortype()
   disp.image(util.deprocess_batch(util.scaleBatch(img_data:float(),win_size,win_size)), {win=display_id, title=title})