topic Clipping .tiff image changes colors of original scanned .tiff image in Data Management Questions

Clipping .tiff image changes colors of original scanned .tiff image

Anonymous User — Thu, 03 Mar 2011 17:22:35 GMT

Original User: scheadley

I have scanned our old zoning maps that are printed on white paper with colored polygons representing the zoning classifications. These were done in 1989 on a plotter.

When I scan them at 75dpi in color as a .tif image, they come out exactly like they look on the hard copy. When I georeference them, then use the Data Management-Raster-Raster Processing-Clip tool, the colors come out much darker and some of the polygons are black. Any reason for this happening? The .TIF files are 3 bands. I uploaded my 2 files as jpeg, but they look exactly like the tiffs.

Thanks
Steve

Re: Clipping .tiff image changes colors of original scanned .tiff image

RobertBerger — Thu, 03 Mar 2011 17:33:50 GMT

Hi,

When you run the clip tool, the tool will automatically calculate statistics that will be used for display. You can try to turn of the stretch on layer properties > symbology tab to see if that is indeed the issue.
If this is your issue you can try to remove the statistics or change that by default no stretch is used. Alternately you can turn of the statistics calculation in the geoprocessing environment and run the clip again.
Is that what you're seeing?

Robert

Re: Clipping .tiff image changes colors of original scanned .tiff image

Anonymous User — Thu, 03 Mar 2011 18:51:58 GMT

Original User: scheadley

I don't think stretch is enabled on the clipped .tif. I looked at the layer properties and it is not checked.

How do you turn off the statistics calculation before the I run the clip?

Re: Clipping .tiff image changes colors of original scanned .tiff image

PatrickTaurman — Thu, 03 Mar 2011 20:26:36 GMT

Your screenshot shows Stretch set to Standard Deviations, so stretch is being applied. Switch this to None, and you will see the display change.

As for not calculating statistics, go into the Environments > Raster Storage Settings and uncheck Calculate statistics when you use the Clip tool.

Re: Clipping .tiff image changes colors of original scanned .tiff image

Anonymous User — Fri, 04 Mar 2011 13:02:02 GMT

Original User: scheadley

That worked! Switching the stretch value to none.

Re: Clipping .tiff image changes colors of original scanned .tiff image

GordonSumerling — Wed, 16 Mar 2011 03:22:08 GMT

Steve,

Be aware, if ArcGIS detects statistics have been generated when it loads an image it will automatically stretch the image for you. You can turn this off though. Go to ArcMap options->Raster->Raster Layer. Set the stretch type to None. Once you have done this then it should not stretch any images again for you.

Also, If you delete the corresponding AUX file with the image, this will remove the statistics and not do a stretch next time you load it.

Cheers
Gordon