From Ra and Rq, you can't do that because that's already processed data.

However, with the Gwyddion processing software, the skewness and kurtosis can also be determined from the image:

http://gwyddion.net/documentation/user-guide-en/statistical-analysis.html

Dear Jürgen Weippert thanks alot for your help.

Dear Tahereh Gholizadeh ,

As Prof. Jürgen Weippert mentioned you can use Gwyddion , for example. However Gwyddion can be complicated sometimes until you get used to it. Specially if you have to do some post-processing like flatten. I can share with you a pdf with a quick guide explaining how to do it step-by-step.

I also recommend this other software:

www.profilmonline.com

you can register for free and is more intuitive.

HOpe this helps,

best regards

Paco

Many thanks to you Dr. Nicolas F. Martinez