problem with raster files - georeference

[Jirka Cajthaml]

Frank Warmerdam napsal(a):

>On 6/27/05, Ing. Jiří Cajthaml <jiri.cajthaml at fsv.cvut.cz> wrote:
>  
>
>>Hi,
>>
>>I have problem with my georeferenced raster files.
>>My area of interest contains over 400 rasters
>>(scanned map sheets, TIF+TFW)
>>
>>Unfortunately, rasters are georeferenced in ArcMap and map sheet
>>on every raster is rotated (because of georeferencing - its OK).
>>
>>My TIF then looks like rotated map and the rest of an rectangular image
>>is filled by some color (thin triangle at the every edge of map).
>>
>>When I want to display these rasters together in mapserver, these color
>>triangles overlay neighbour maps.
>>
>>You can see example at
>>http://gama.fsv.cvut.cz/~cajthaml/example/example.jpg
>>    
>>
>
>Jiri,
>
>I am a bit surprised that you are encountering these problems.
>The mapresample.c code should be kicking in for rotated input
>rasters, and it should not be overlaying existing information with
>"blankness" from outside the original files.  I am assuming that your
>source files don't have any blank rectangles in them - is that right?
>
>If you can submit a bug report with sufficient information for me to 
>reproduce the problem (ie. pointers to a map file and data files I
>can use) then I can try to look into this.   Make sure the bug report
>gets assigned to me. 
>
>Best regards,
>
>  
>
I perhaps found the problem.

Data I've got were referenced, but saved without transparency and 
"blankness" was filled
with some color. Images were saved with indexed colors (255), 
not-compressed TIF.

When I resaved image in Photoshop in RGB with transparency option and 
LZW compression,
rasters in mapserver are OK ("blankness" doesn't overlay data).
Size of raster increased by aproximately 20%.

regards Jiri