I would like to write a condition in ArcGIS 10.1 in Raster calculator.

I have 2 overlapping rasters (Ras1.img, Ras2.img) with different attributes in attribute table:

  • Ras1.img: Class - results of supervised maximum likelihood classification
  • Ras2.img: Att - landuse, raster converted from shapefile polygon format

I want to change pixel values Class in Ras1.img based on the values in Att, Ras2.img. something like:

if ((Ras1.img, Class == 20 & Ras2.img, Att == 5), then change Class value 20 in Ras1.img  to Class 25))

I can't figure that out. It is super simple in R, but I have no idea how to make it in ArcGIS 10.1.

I was trying to figure that out by : http://resources.arcgis.com/en/help/main/10.1/index.html#//009z000000zn000000

and applying something like:

Con(("landuse1" == 1) & ("landuse2" == 5), "landuse1" + "landuse2", 99)

but I don't understand where I specify the attributes of my rasters I would like to change?

  • Rasters usually have only thing which 'Cell value', no attributes. Indeed Raster calculator uses the Cell Value for the 2 rasters while comparing.
    – Shiko
    Dec 2, 2016 at 9:51
  • when I tried just a simple expression i.e. Con(("Ras1" == 20), 0, 25) , I didn't get back a correctly reclassified output.. So I think I am making something wrong..
    – maycca
    Dec 2, 2016 at 9:53
  • Question please, the reclassified rastes you have were produced from ArcGIS supervised/unsupervised tool ?
    – Shiko
    Dec 2, 2016 at 9:59
  • yes, Raster1 yes. The second is the true type of landuse, by which I want to correct my classification results
    – maycca
    Dec 2, 2016 at 10:00
  • What I know that the output of supervised classified is not exactly RASTER image, even you may check the output file type. May be you need to convert this image to Raster.
    – Shiko
    Dec 2, 2016 at 10:05

1 Answer 1


Try the Reclassify tool: http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/reclassify.htm

Open this tool and you should be able to input your raster, then redefine pixel value(s).

  • @maycca if you liked this answer please "accept" it so the question does not show as unanswered
    – Stella
    Apr 17, 2018 at 16:43

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