trouble displaying ortho

[Dylan Keon]

I'm having trouble displaying a TIFF image (merged orthophoto).  It
looks pretty noisy in my mapserver app.

Bad image: http://gis.nacse.org/mstemp/109224912061641.png
What it should look like: http://gis.nacse.org/mstemp/ortho_small.png

I tried displaying it as both 8-bit and 24-bit with no difference, but
it should display ok as 8-bit anyway.  The funny thing is it looks
correct in an existing ArcIMS app, and in the eog and kview image
viewers.  But then it looks noisy in the mapserver app, in gimp, and
also when I view it in Irfanview on Windows.  Not sure what's up.

Thanks,
Dylan


=== Here's some info on the image ===

$ identify ortho.tif
ortho.tif TIFF 3428x2573+0+0 PseudoClass 256c 8-bit 8.4m 0.100u 0:01
identify: unknown field with tag 33922 (0x8482) ignored. (ortho.tif).

$ gdalinfo ortho.tif
Driver: GTiff/GeoTIFF
Size is 3428, 2573
Coordinate System is `'
Origin = (558466.500000,4903753.000000)
Pixel Size = (4.00000000,-4.00000000)
Metadata:
   TIFFTAG_SOFTWARE=Arc/Info
   TIFFTAG_XRESOLUTION=0.25
   TIFFTAG_YRESOLUTION=0.25
   TIFFTAG_RESOLUTIONUNIT=1 (unitless)
Corner Coordinates:
Upper Left  (  558466.500, 4903753.000)
Lower Left  (  558466.500, 4893461.000)
Upper Right (  572178.500, 4903753.000)
Lower Right (  572178.500, 4893461.000)
Center      (  565322.500, 4898607.000)
Band 1 Block=3428x3 Type=Byte, ColorInterp=Palette
   Color Table (RGB with 256 entries)
     0: 0,0,0,255
     1: 1,1,1,255
     2: 2,2,2,255
     ... etc ...


=== Minimal mapfile, works with shp2img ===

SIZE 480 320
EXTENT 558788 4893725 572143 4903558

IMAGETYPE png8
#IMAGETYPE png24

OUTPUTFORMAT
   NAME png8
   DRIVER "GD/PNG"
   MIMETYPE "image/png"
   IMAGEMODE PC256
   FORMATOPTION "INTERLACE=ON"
END
OUTPUTFORMAT
   NAME png24
   DRIVER "GD/PNG"
   MIMETYPE "image/png"
   IMAGEMODE RGB
   FORMATOPTION "INTERLACE=ON"
END

LAYER
   NAME 'ortho'
   DATA /gis/data/temp/ortho.tif
   STATUS ON
   TYPE RASTER
END

END