Hi Andre,

I think that i understand the issue. The input image is an indexed color
image with a palette associated.

OTB interpret the color table and read directly this value (you can't
access the pixel value in the image but only the interpreted value)

Note that there is a bug related to this issue:

https://bugs.orfeo-toolbox.org/view.php?id=1079

Guillaume had proposed a fix (see bug thread) but it is not yet
integrated...

Easy fix for you: use the interpreted value in your bandmath expression
(im1b1==2 will corresponds to im1b1==255 and im1b2==0 and im1b3==255 and
im1b4==255). It is a bit cumbersome but it should work.

Hope we'll get soon a patch to handle palette color indexed image properly
in OTB.

Regards,

Manu



2016-12-06 14:36 GMT+01:00 André Stumpf <[email protected]>:

> ...I forgot to attach the input file. The problem is mainly that, using
> the commands I described, I get a test.tif with all pixels set to nan.
> Maybe it's related to the input file than? By the way I'm running version
> 5.6.1
>
> On Tuesday, December 6, 2016 at 2:28:01 PM UTC+1, Manuel Grizonnet wrote:
>>
>> Hi André,
>>
>> I don't think that there is something wrong with the syntax.
>>
>> Can you give more info on what is wrong or what does not work in the
>> output of the BandMath compare to what you expect?
>>
>> 2016-12-06 14:15 GMT+01:00 André Stumpf <[email protected]>:
>>
>>> Hi,
>>>
>>> I have the attached raster which is the output of a cloud masking
>>> algorithm and would like to produce a binary mask from it.
>>> I was thinking that I could use the following syntax to set for example
>>> all pixel==2 to 1 and the rest to 0.
>>>
>>> otbcli_BandMath -il S2A_OPER_MSI_L1C_TL_SGS__20161
>>> 003T232748_A006704_T60GTU_cloud_mask.img -out test.tif uint8 -exp
>>> "im1b1==2 ? 1 : 0"
>>>
>>> The output tif however comprises only missing values.
>>>
>>> Ideally I would like to set all pixel which are equal to 2 or 4 or 5 to
>>> 1 and the rest to 0 like this:
>>> otbcli_BandMath -il S2A_OPER_MSI_L1C_TL_SGS__20161
>>> 003T232748_A006704_T60GTU_cloud_mask.img -out test.tif uint8 -exp
>>> "im1b1==2 or im1b1==4 or im1b1==5 ? 1 : 0"
>>> ...which of course doesn't work neither.
>>>
>>> Maybe somebody has an idea what is wrong with the syntax or the input
>>> data?
>>>
>>> Cheers,
>>> André
>>>
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>>
>>
>>
>> --
>> Manuel Grizonnet
>>
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-- 
Manuel Grizonnet

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