[gdal-dev] Problem with black edges to DOQQs using JPEG in Tiff compression

[Brian Case]

steve and all

after reading my reply  I noticed a major error

"first, if your data is non lossy you need to nearblack -nb 0 -near 15"



this should read "nearblack -nb 0 -near 0"


Brian



On Sun, 2017-02-12 at 13:16 -0800, Brian Case wrote:
> Steve,
> 
> first, if your data is non lossy you need to nearblack -nb 0 -near 15
> 
> however your DOQQ's dont have a collar so there is no reason to
> nearblack
> 
> gdalwarp -dstalpha will crate an alpha band to mask out the collar after
> gdalwarp rotates the image. no nead to nearblack the output of gdal
> warp.
> 
> when using gdal_translate to create a tiff with a mask band, and you
> warped file has a alpha band, gdal_translate -b 1 -b 2 -b 3 -mask 4
> this will crate a mask band from the alpha band
> 
> brian
> 
> On Sat, 2017-02-11 at 18:18 -0500, Stephen Woodbridge wrote:
> > Hi All,
> > 
> > I need your wisdom. I'm downloading NAIP DOQQs in GTiff format and I 
> > have a processing chain something like the following:
> > 
> > gdalwarp -t_srs EPSG:4326 -dstalpha -r "bilinear -multi -co TILED=YES 
> > -dstnodata '0 0 0' srctiff tmpfile
> > 
> > nearblack -nb 15 -q tmpfile
> > 
> > gdal_translate -co TILED=YES -co JPEG_QUALITY=90 -co COMPRESS=JPEG -co 
> > PHOTOMETRIC=YCBCR -b 1 -b 2 -b 3 -mask auto --config 
> > GDAL_TIFF_INTERNAL_MASK YES  tmpfile, target
> > 
> > nearblack -nb 5 -q target
> > 
> > gdaladdo -clean -r bilinear  target 2 4 8 16 32 64 128 512
> > 
> > And create a tileindex for mapserver of all the tiffs
> > 
> > If I skip the gdal_translate (ie: JPEG compression) and the 2nd 
> > nearblack, the doqq tiles are perfect with no nearblack edges between 
> > the doqq tiles. But when a JPEG compress them, I get edges between the 
> > doqqs like this:
> > 
> > http://imaptools.com:8080/dl/doqq-issue.jpg
> > 
> > I've never used the JPEG in tiff compression and I'm very impressed by 
> > the amount of size reduction there and how good the image remains, but I 
> > have not been able to figure out the magic trick to clearing the edge 
> > artifacts.
> > 
> > Any help would be appreciated.
> > 
> > Thanks,
> >    -Steve
> > 
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