How to get Attenuated images using Automatic Analysis?

Respected Sir/Madam,

I want to get attenuation imaging of a image file, using MatLAB. For that I was able to get the mean square error and the exponential fitting of the image and got minimum and maximum error value. Now how do I plot the attenuation imaging using imagesc() function?

Details about attenuation imaging can be found in this link: https://www.osapublishing.org/view_article.cfm?gotourl=https%3A%2F%2Fwww.osapublishing.org%2FDirectPDFAccess%2F6BEE300A-E7B0-DB26-8498CEA284447F1D_256437%2Fboe-4-7-1014.pdf%3Fda%3D1%26id%3D256437%26seq%3D0%26mobile%3Dno&org=

Check figure 5, page 8.