Output image depth is greater than 8 - Output image cannot store colormap

Last Published: April 25, 2020

Error Message

Exporting a grid to an image with GRIDIMAGE returns the message:Output image depth is greater than 8
Output image cannot store colormap
Converting Grid to Image ...


The input grid contains a value larger than 255. Eight-bit images can only store pixel values in the range of 0 to 255.

The warning message indicates the output image will not be 8-bits and that a colormap file will not be created. The output image will be written as a 16-bit greyscale file, which has a range of potential values from 0 to 65535.

Solution or Workaround

If the output image must maintain the grid's colormap, you must modify the grid to fit within a 0 to 255 value range. You can use the SLICE or CON functions to change the value range of the grid.

Using the SLICE functionL
newgrid = SLICE(oldgrid,EQINTERVAL,256,0)

Using the CON function:
newgrid = CON(oldgrid > 255, 255, CON(oldgrid < 0, 0, oldgrid))

You must edit the colormap in an ASCII text editor so the color definitions are associated with the correct areas in the new 0-255 grid.

For a discussion of the colormap file format, see the ArcInfo online Help section Contents > Spatial modeling > Cell-based Modeling with GRID > Displaying grids > Assigning colors for grid display > Creating a colormap file.

Article ID:000002110

  • ArcMap 8 x

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