[Qgis-user] Displaying 16 bit per channel images

[Gabriel Lema]

Thank you for your replies
What finally worked for me was to open the image with QGIS and right
clicked on the item under the Layers, and choose save as.. Then choose
the Renderized image option.
Thank you for your help.
Regards,
Gabriel

On Sat, Feb 14, 2015 at 6:01 AM, Andre Joost <andre+joost at nurfuerspam.de> wrote:
> Hello,
>
> QGIS usually uses 24bit colours using three bands with values between 0 and
> 255. An alpha channel can be added, if the file format supports it (JPG does
> not).
>
> If you want to save bandwidth, you can use paletted colours with
>
> Raster -> Conversion -> RGB to PCT
>
> allowing 256 colours or less in one band with values between 0 and 255, and
> additional palette information (colour table) in the file header.
>
> In GDAL, RGB2PCT.bat does the same, but not gdal_translate.
> gdal_translate -expand rgb does only the other way round: from palette to
> three bands.
>
> HTH,
> André Joost
>
> Am 13.02.2015 um 21:38 schrieb Gabriel Lema:
>
>> Hello,
>>
>> I was wondering what QGIS does to display 16 bit per channel RGB
>> images. I would like to covert them to 8 bit per channel normal PNG or
>> JPG image, but when I save it using the "Save as..." in the "Project"
>> menu, I get a low resolution image.
>> If I could have access to the conversion from 16 bit to 8 bit that
>> QGIS does, which makes a good looking RGB image, I could do that same
>> conversion on any other software, and save it full resolution. Is it a
>> gamma correction? I've tried many different, but haven't been
>> successful so far.
>> If I save it using gdal_translate I get a greenish looking image, that
>> is very different from the good looking image that QGIS displays.
>>
>> Thank you for your help.
>> Gabriel
>>
>
>
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