Thanks for your quick response, Uwe. Yes, all the tif files have got the same color table. I checked that and added the -pct option. But I think I forgot to remove the old merged one I generated without the -pct option. Now that I have removed the old merged one, a merged colored tif file is successfully generated after running the same command :)
<br>________________________________
<br>From: Schmitz, Uwe [via OSGeo.org] [<a href="/user/SendEmail.jtp?type=node&node=5955057&i=0" target="_top" rel="nofollow">[hidden email]</a>]
<br>Sent: 24 January 2011 09:24
<br>To: Heng Feng
<br>Subject: AW: [gdal-dev] An issue about using GDALWARP todotheNTv2transformation
<br><br>Heng,
<br><div class='shrinkable-quote'><br>>
<br>> Hi Uwe,
<br>>
<br>> I have been trying to use gdal_merge.py to merge
<br>> a few 8 bit colored .tif tiles together. Having
<br>> tried all sorts of options for this command, I
<br>> always ended up with a merged 8-bit grayscale picture.
<br>> I did a search on the internet and found a couple of
<br>> posts related to this, however it seemed to me that
<br>> the gdal_merge.py just does not have the ability
<br>> to preserve the color. Did I get the wrong idea about
<br>> this? Do you have any suggestion to solve this problem?
<br>>
</div>you have to specify "-pct" to grab the color table
<br>of the first merged tile for the result file.
<br>And, very important, all input tiles need to have
<br>the *same* color table, because merging is done
<br>on pixel values (that means channels).
<br><br>> Not sure if I should post a separate message for
<br>> this gdal_merge.py issue. I just thought this would
<br>> be the quickest way to get the help :)
<br>>
<br>Yes, IMO a seperate post would have been better and
<br>addressing it to me wouldn't always help to get a fast
<br>response ;-)
<br><br>Regards
<br>Uwe
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