Opened 16 years ago
Closed 16 years ago
#1744 closed defect (fixed)
Bad colors for a CADRG file
| Reported by: | Even Rouault | Owned by: | Even Rouault |
|---|---|---|---|
| Priority: | normal | Milestone: | 1.5.0 |
| Component: | GDAL_Raster | Version: | svn-trunk |
| Severity: | normal | Keywords: | CADRG |
| Cc: | warmerdam |
Description
This may be directly related with bug #913, as the data come forom the same source. With some files coming from http://www.aeroplanner.com/cadrg/Samples/CADRG_SNYA.zip, we have an incorrect display of colors in OpenEV, whereas it seems correct in Global Mapper. See for example 0058X00A.LF2. I've attached the CADRG file, a screenshot made with OpenEV and one made with Global Mapper.
Attachments (5)
Change History (9)
by , 16 years ago
| Attachment: | 0058X00A.LF2 added |
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by , 16 years ago
| Attachment: | 0058X00A.LF2.GlobalMapper.jpg added |
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Screenshot made with Global Mapper
comment:1 by , 16 years ago
But the whole CADRG mosaic is displayed correctly when using the OGDI bridge like in :
openev 'gltp:/rpf/home/even/data/RPF:"1:500K@2@CADRG@DMAAC@0":Image'
by , 16 years ago
| Attachment: | 0058X00A.LF2.OpenEV_OGDI.jpg added |
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Screenshot made with OpenEV using OGDI bridge
comment:2 by , 16 years ago
The attached patch fixes the issue. However as I'm not (yet, lol) a CADRG or NITF specialist, I can't guarantee this is always correct.
Basically, I ported a function from the RPF OGDI driver that reads the colormap section, which was ignored in the GDAL NITF driver. Why it is necessary for this image ? I've observed that for that image the LUT located at offset 937 of the file is not in the expected format R1,R2,...,R176,G1,G2,...,G176,B1,B2,...B176 but in the follwing one : R1,G1,B1,A1,R2,G2,B2,A2..... !!! and it's truncated around color index 130 by other header fields (chIMODE, nBlocksPerRow, etc...)
by , 16 years ago
| Attachment: | gdal_svn_cadrg_colormap.patch added |
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comment:3 by , 16 years ago
| Cc: | added |
|---|---|
| Milestone: | → 1.5.0 |
| Owner: | changed from to |
Even,
Go ahead and apply this patch, but only in trunk since it is non-trivially risky. Based on a quick scan it looks fine.
CADRG file coming from http://www.aeroplanner.com/cadrg/Samples/CADRG_SNYA.zip