How to edit min/max values in Symbology when grayed out?

[JanelleKmetz]

Hello. I am using ArcPro and I have imported thermal infrared raster images (as TIFF files) which have a min and max value representing the stretch of thermal temperature data. I want to change the min and max values of my rasters so to alter the color/range of temperature values. 

I know you can change min / max in the Symbology tab, but for me it is grayed out and I cannot change the values. I think there is a way to get around this issue. Can anyone help? 

[DanPatterson]

what about changing the clip min, max?

[JanelleKmetz]

Hi Dan, thank you for your response. If I change those parameters, the image does change dramatically, but see that the pixel value range is still the same (i.e. 7... - 36.....). I am not fully sure what the clip does, but I do need the pixel values to represent the correct temperature scale that I want to specify.

[DanPatterson]

Sorry I don't have anything to test with, perhaps trying something other than stretch has other options

[JanelleKmetz]

That's ok! Thank you for your suggestions! Maybe someone else will help me out 🙂

[MervynLotter]

One option would be to create a new raster with the required/desired range of min and max values using the Create random raster GP tool.  But use the GP tool listed under Data Management toolset  and not  Spatial Analyst tool as the former lets you specify minimum and maximum values. Then symbolize it and save as lyrx file. Then from your thermal infrared raster images, import the symbology from your new lyrx file you just created.  

It should give you your desired symbology. 

[Jonathan_Goergen]

I was just looking into this issue to make a method for staff I support to harmonize symbology across different DEM tiles and I found a solution.  It is a crappy solution, but par for the course. 

• With the raster symbolized as you have it, right click on the raster in the Contents Panel and select "Sharing -> Save As Layer File"

• Navigate to where you saved the layer file and open the file in Notepad++ or Notepad

• Look for this block of text (or use the find function and search for the minimum value), note this is from my work: 

"stretchClasses" : [
{
"type" : "CIMRasterStretchClass",
"label" : "80",
"value" : 80
},
{
"type" : "CIMRasterStretchClass",
"value" : 681.34516143796498
},
{
"type" : "CIMRasterStretchClass",
"label" : "1125.19",
"value" : 1125.1899414062
}

The first label and value will be the minimum, the middle pair appears to be the halfway point between the min and max (I should go and update the new middle point, above shows the original middle point)m and the third pair is your max values.  You can set these values as you'd like and save the lyr file.

After making these changes you can select the hamburger from the upper right of the symbology and select "Import from Layer File" and select your modified layer file and the new stretch will occur.