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Problem: ArcMap monochrome TIFF export displays incorrectly or reversed

Description

Monochrome group 4 TIFFs exported from ArcMap 9.x are displayed as a reversed or negative image or are 'chunky' or 'blocky'.

Cause

Some TIFF viewers do not read this format correctly, and reverse black and white values, rendering a negative image. Microsoft (MS) Paint is one example of a viewer that renders CCITT Group 4 TIFFs incorrectly. Both Adobe Photoshop and ArcMap display the values correctly.

There has also been a significant change in the way ArcMap converts map images from color to 1-bit on export.

At 8.x, the color map image was automatically dithered, giving a false gray effect by selectively filling pixels according to the brightness of the original color and surrounding pixels.

At 9.x, dithering only occurs in 8-bit exports; 1-bit exports will not dither. The 9.x exporters create a pure 1-bit representation based on a user-defined mask color or threshold.

Solution or Workaround

  • This problem has been fixed with ArcGIS Desktop 9.1 Service Pack 2. Download and install ArcGIS Desktop 9.1 Service Pack 2 or higher. See the corresponding link in the Related Information section below.
  • If unable to upgrade to ArcGIS Desktop 9.1 Service Pack 1 or higher, export to an 8-bit TIFF and then use a post-processing tool, such as Adobe Photoshop or the shareware application ImageMagick, to convert the file to a dithered 1-bit CCITT Fax Group 4 TIFF.

    Note:
    ImageMagick has not been tested by ESRI nor does ESRI support the application.

Related Information