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Raster: Converting digital numbers to real world values

Question asked by premachu on Aug 30, 2016
Latest reply on Aug 30, 2016 by Dan_Patterson

I have downloaded 2 chlorophyll maps which generally have cell values of 0-255. 


How can I convert these into real world values? 


Following the instructions linked here and here, I have been unable to convert the byte value (0-255) to geophysical values (0-64 mg m3)




I have downloaded L3 choloprhyll data maps. I have extracted and attempted to convert the cell values in R, with no luck. 


Is this possible in Arcmap and how would it be achieved? 

# DN = digital number / cell value / cholorphyll L3 data 

# value = 10^[(DN * slope) + intercept]
# raster = Modis cholorphyll sattelite image

# Code ran in R

((values(raster)* 0.015) -2.0)^10)


# Does not return real world values (values between 0-64 mg m-3)

Linked below is one of the raster images I have attempted to convert into real world geophyiscal values, which was downloaded from Giovanni (after clicking the link, click plot, select an image and download as a TIFF. Attachment limits prevent me from directly uploading image. OR just download image attachment in comment below)




How can I convert the pixel values (0-255) of a cholorphyll L3 TIFF image into real word values, using Arcmap?