Changing min max of Stretched Raster with ArcPy?

Question

I have two rasters r1 & r2:

Maximum cell value of r1: 0.9

Maximum cell value of r2: 0.3

Minimum value for both is 0

I am using a color gradient: white - yellow - green - blue - red - black

When I apply the symbology of r1 on r2, the max value of r2 (0.3) is black. The symbology is set in relation to the value range of r2.

r1 = arcpy.mapping.Layer("r1.lyr") mxd = arcpy.mapping.MapDocument("myMap.mxd") df = arcpy.mapping.ListDataFrames(mxd)[0] r2 = arcpy.mapping.ListLayers(mxd, "r2.tif", df)[0] arcpy.ApplySymbologyFromLayer_management(r2, r1)

However, I want to compare the two rasters. The values of r2 should therefore be symbolized in relation to the values of r1. The max value of r2 would be yellow in comparison to the value range of r1.

Manually, you can do this in the symbology tab by changing the raster max value by hand:

However, I have a large dataset and I would have to do this a couple of hundred times.

Is there a way to automate this with ArcPy?

Answer 1

I don't believe you can access those properties through the standard functionality of arcpy as the symbologyType property on a raster layer with a stretched symbology returns the unsupported "other".

Update October 2019:

With the release of version 2.4 of ArcPro you can access most of the layer properties via CIM, this includes the symbology. Using the AddIn CIM Viewer you can see the StretchType which indicates this is a property that can be altered via CIM using a few lines of python.

Screen shot from CIM Viewer

This is new functionality exposed in ArcPro, not ArcMap. Be aware this approach by-passes all the inbuilt error checking in arcpy so you can potentially blitz your project if you are not careful, heed the warn on the ESRI help file!