Extracting specific roads from raster image using ArcGIS Desktop

[SLobodanKomatina]

I want to create a line shapefiles of white roads from the raster file (screenshot1) using ArcGIS:

My idea is to use ArcScan toolbar, but first of all I need to classify roads pixels values from raster. For that I have used ISO Unsupervised classification tool with a number of 30 classes. The results are not good for me because I got the unclear pixel values which are unusable for ArcScan vectorisation (screenshot2):

Of course, if I have a clear pixels defining the roads I will use Reclassify tool to filter get just two pixel values (one which I need and one which don`t). Now I need to know is there any way to solve my problem?

[G_shashiReddy]