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20010323: 20010322: image display problems in garp, nsat and nmap



David,

As suspected, your imagery is 2 byte. The reason you are seeing white is that 
the data values predefined in the $GEMTBL/sat/imgtyp.tbl specify a data range
for the pixel values from 0 to 255 (all of your values are much grater than 
255),
so you end up with he high end color for all the data values.

To display your IR channel 2 image that you uploaded, I modified the
imgtyp.tbl entry for the GOES-8 IR2 2 byte pixel depth entry as follows:

! SATELLITE IMAGE TYPES
! ---------------------
!                   |IMG     |      |      |SAT ID|IMGTYP| PIXEL| DEFAULT      |
!SAT ID             |TYP     |   MIN|   MAX|NUMBER|NUMBER| DEPTH| LUT FILE     |
!(20)               |(8)     |   (6)|   (6)|   (6)|   (6)|   (6)|      (14)    |
!                   |        |      |      |      |      |      |              |


!GOES8                IR2           0    255     70      2      2 ir_sab.tbl
GOES8                IR2           0  16384     70      2      2 GRAY


The ! commented out entry is what was in the table be default.
I increased the upper end to 16384 and set the default color table to
GRAY. Now the imagery is displayed in a range of values that allows
the image to be viewed. 

You can similarly modify the table for WV. The table is cosulted every
time an image is loaded, so as soon as you update the table, the change 
will be in effect.

The color bar in Garp will reflect raw values without the calibration block.

Steve Chiswell
Unidata User Support



>From: David Fitzgerald <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200103231539.f2NFdoL29622

>Chiz,
>
>I ftp'd a file named IR_19990817_1102 to ~gbuddy/incoming.  
>
>Dave
>
>-----Original Message-----
>From: Unidata Support [mailto:address@hidden]
>Sent: Thursday, March 22, 2001 6:36 PM
>To: David Fitzgerald
>Cc: 'Unidata Support'; Richard Clark
>Subject: 20010322: 20010322: image display problems in garp, nsat and
>nmap 
>
>
>
>Dave,
>
>That message indicates that you have 2 byte imagery (not the same as what is
>in the data stream for IDD).
>
>Can you upload one of the offending IR or WV images?
>
>Thanks,
>
>Steve
>
>
>>From: David Fitzgerald <address@hidden>
>>Organization: UCAR/Unidata
>>Keywords: 200103222227.f2MMRYL28443
>
>>Chiz,
>>
>>The images are for GOES-EAST data from the summer of 1999.
>>Here is what areaInfo -v gives me:
>>
>>/var/data/NECOPS_IMAGERY/temp% areaInfo -v ./IR_19990817_1102
>>zsiz 2 != 1 not supported
>>
>>I get the same result for WV AND VIS, but visible images are displaying
>>fine.
>>
>>Dsve
>>
>>
>>
>>-----Original Message-----
>>From: Unidata Support [mailto:address@hidden]
>Sent: Thursday, March 22, 2001 4:58 PM
>>To: David Fitzgerald
>>Cc: 'address@hidden'; Richard Clark
>>Subject: 20010322: image display problems in garp, nsat and nmap 
>>
>>
>>>From: David Fitzgerald <address@hidden>
>>>Organization: UCAR/Unidata
>>>Keywords: 200103222122.f2MLMFL26416
>>
>>>I have been getting some archived satellite images from the SSEC and am
>>>having a problem viewing the Infra-red and Water Vapor images using Garp,
>>>Nsat and Nmap.  Visible images display just fine, but the IR and WV show
>up
>>>as all white images.  The IR and WV images DO work in McIDAS (go figure
>>>coming from Wisconsin!), but unfortunately they have to work in Garp.  Do
>>>you know of any reason why Garp would NOT display McIDAS AREA files
>>>correctly, particularly only for IR and Water Vapor?  If so how do I fix
>>it?
>>>
>>>Thanks in advance!
>>>
>>>Dave
>>>
>>>********************************************************************
>>>David Fitzgerald                     Phone:  717-871-2394
>>>Distributed System Specialist        Fax:      717-871-4725
>>>Millersville University             
>>>Millersville, PA 17551          E-mail: address@hidden
>>>
>>>
>>
>>
>>David,
>>
>>If the files are "raw" images without the calibration block, the default
>>GEMPAK color table will be incorrect. Or, if there is no imgtyp.tbl
>>entry for the platform, you could be [IM -1] no image but ist doesn't
>>sound like that is the problem. You don't mention what satellite the
>>images are for- so I can't guess as to whether that might be a problem. 
>>Can you send me the output of "areaInfo -v" and/or uplink one of the files 
>>to ~gbuddy/incoming?
>>
>>Steve Chiswell
>>***************************************************************************
>*
>><
>>Unidata User Support                                    UCAR Unidata
>Program
>><
>>(303)497-8644                                                  P.O. Box
>3000
>><
>>address@hidden                                   Boulder, CO
>80307
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>>
>
>****************************************************************************
><
>Unidata User Support                                    UCAR Unidata Program
><
>(303)497-8644                                                  P.O. Box 3000
><
>address@hidden                                   Boulder, CO 80307
><
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>Unidata WWW Service                        http://www.unidata.ucar.edu/
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