[QUOTE]Chapagain wrote Hello Dears, I am using Landsat7 on ENVI. I calculate NDVI through Tools>Band Math (band 4 and Band 3). Now, how can I classify the NDVI values, ( eg. 3.0-4.0 , 5.0-7.5 and so on). Please let me know if you have some ideas. Thanks, Alvin [/QUOTE]

I would display the NDVI image and then go to Tools ->Color Mapping ->Density Slice. This tool allows you to assign values or ranges of values to a specific color. Once you assign all the ranges of values to the class colors you want you can save it to an ENVI classification image from the Density Slice menu under File ->Output Ranges to Class Image.

Thank you, I found 16.0000 to 77.6250 (Red) 77.6250 to 139.2500 (Green) ,,,,,,,,,,,,,,,,,,,,,,, 447.3750 to 509.0000 (sea Green) but how can I rearrange 0 to 1 in different classes ( 0-0.1, 0.1-3.0, ......7.5-8.0) because I want to the vegetation type Thanks, Nipesh

You don't have to use the default ranges. You can clear those ranges and under Options it allows you to add New Ranges manually.

Thank you I got

Hello, Please how can I preprocessing of my image. how can I remove cloud and noise. I am using Landsat image ETM7 in ENVI 4.3 Thanks,

There are different ways to remove noise and clouds. For clouds, do you want to just mask them out of your processing, or do you want to try to replace the clouds with something else? Do you know what you'd want to replace them with? For example, do you have another image of the same area, without clouds? What is the noise like? For example, is it striping, or more random? For more random noise, you can do things like apply a forward MNF transform, then an inverse MNF transform, leaving the highest (noisiest) MNF bands out of the inverse transform. - Peg

I have Landsat7 using ENVI 4.3. how could I preprocessing , geomatric correction. i am waiting for good suggestions, Thanks, Alvin