I have an image with value ranging from -1 to +1.
I want to convert this into 0-255 (8bit).
How can this be done using ArcGIS for Desktop or ERDAS IMAGINE?
[GIS] Floating point to 8-bit unsigned raster conversion using ArcGIS for Desktop or ERDAS IMAGINE
arcgis-desktoperdas-imagine
Related Solutions
Try using the layer stack tool in the Spectral pull-down in the raster tab. 
Select the bands you want to use in the tool. For example, I'm selecting band 1 to separate the band from a 12 band raster.
Save the band you selected. The output should now be a band separated-out from the stacked image.
You could try Linear Contrast Stretch (Linear Contrast Stretch, Pg 145) in ERDAS IMAGINE. This tool will assess the minimum and maximum DN/pixel value in your image and stretch it in the range of 0-255.
The same can also be done using ArcGIS, as you required. Linear Stretch using ArcGIS.
This is a form of radiometric enhancement of the image, wherein you can shift the min-min values of the image as desired....
Let me know if this helps, and happy to help with more queries until you get your results...
Best Answer
You will want to stretch your floating point data from (-1 to 1) to (0 - 255). You can accomplish this very easily in Erdas Imagine:
Raster tab > Resolution Group > Radiometric > Rescale