my tif image data type is float( my data is in between -1 to +1). I want to convert it into 8bit unsigned integer. I used ErdasImagine import tool to do this, while conveting into img also. but in the out put image the data is only shows 0 and 1. what is the problem. I want to convert -1 as 0 and +1 as 255. How can I do this in erdas and arcGIS

My tif image data type is float  (i.e. my data is between -1 to +1) and I want to convert it into 8bit unsigned integer.

I used ERDAS IMAGINE import tool to do this, while converting it into img also.

However, in the output image the data is only shows 0 and 1. 

I want to convert -1 as 0 and +1 as 255.

How can I do this in ERDAS IMAGINE and ArcGIS for Desktop?