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> What I mean by switched is:
> 
> The image is not out focus nor rotated. It looks that it started to extract from the
> middle of the image and finished at the beginning of the image. The result is, what is now 
> the first half of the image is really the second part of the image. 
> 
> I hope this is more explicit.
> 
> Cristina
> 
> 
> cis@fct.unl.pt
> 

Cristina,

Please make sure you have correct default window setup for GRASS x,y LOCATION,
which means:

	1 The north and south coordinates are negative;
	2 All of the coordinates are offset by 0.5. the northern edge is 0.5
	  less than the chosen first row, the southern edge is 0.5 greater than 
	  the chosen last row, the west edge is 0.5 less than the chosen first
	  column, and the east edge is 0.5 larger than the chosen last column.
	3 The north coordinate is greater than the south coordinate, and
	4 the east coordinate is greater than the west.

The reason the north and south coordinates are negative is because GRASS 
requires that the window values decrease from north to south but the row
coordinates of image file increase from north to south. Assigning negative 
values to the rows allows them to decrease from north to south and, by ignoring
the minus signs, the correct row numbers are reported. 

When imagery data are extracted into an x,y coordinate LOCATION in GRASS, the
initial start-up coordinates are of little significance, the mapset window will
be changed to match the extracted rows and columns from the original files.

I suggest the following x,y coordinate default window:

                               NORTH
                               -0.50

               WEST 0.50                     EAST 1000.50

                               SOUTH
                              -1000.50

               RESOLUTION: E-W: 1.00
                           N-S: 1.00

By the way, have you tryed directly copy the imagery file from optical disk
into your GRASS x,y coordinate LOCATION under cell subdirectory, then 
"r.support" it ? It may worth to try.

Good Luck !
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