[Qgis-user] GTiff compression issues

[Sebastian Gutwein]

Not my area of expertise but my first suspect would be the alpha channel
(the A in RGBA or transparency). JPEG doesn’t support an alpha channel. You
might try png or jpeg 2000 as an alternative.


On Thu, Jan 21, 2021 at 2:12 AM Yury <yury.zammit at gmail.com> wrote:

> Hi,
>
> I am using QGIS to try and compress hi-res drone imagery.  I am using GDAL
> tools, such as 'Clip Raster by Extent' .  In the command line parameters I
> am adding the following:
>
> -co COMPRESS=JPEG -co TILED=YES --config GDAL_TIFF_INTERNAL_MASK YES.
>
> The original image is RGBA.
>
> Compression is significant (which is what I need) and visually there is
> not much of a difference.  However, when zooming further in (1:200), I
> noticed that some raster cells have turned white.  When inspecting, it
> appears that the compression is changing the data of one or more of the
> bands to nodata.  How can this be resolved?
>
> I am using QGIS 3.10.8
>
> Thanks
>
> Yury Zammit
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-- 
Sent from a phone. Amazing! But possibly garbled. Sebastian Gutwein
Regenerative Design Group 1 Chevalier Ave Greenfield MA Bas at rdgland.com
(631) 241-1018
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