#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
-------------------------+--------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Keywords: r.out.png | Platform: All
Cpu: All |
-------------------------+--------------------------------------------------
Hi,
Peter Löwe discovered that r.out.png does not respect GRASS_TRANSPARENT or
GRASS_PNG_COMPRESSION, which limits the module's usefulness. (especially
the lack of NULL->alpha)
I'm guessing we should have it respect both GRASS_TRANSPARENT and a module
flag, if they conflict I guess go with the enviro variable.
Same for compression with a module option=1-9.
a work-around for now is to use the PNG driver with GRASS_WIDTH and HEIGHT
taken from the image meta data.
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Comment (by glynn):
Replying to [ticket:967 hamish]:
> Peter Löwe discovered that r.out.png does not respect GRASS_TRANSPARENT
or GRASS_PNG_COMPRESSION, which limits the module's usefulness.
(especially the lack of NULL->alpha)
> I'm guessing we should have it respect both GRASS_TRANSPARENT and a
module flag, if they conflict I guess go with the enviro variable.
> Same for compression with a module option=1-9.
You guessed wrong
GRASS_TRANSPARENT and GRASS_PNG_COMPRESSION are for the display drivers,
which don't have the option of reading parameters from the command-line,
so they have to use environment variables instead.
r.out.png should use command-line options; it shouldn't be looking at
environment variables.
While you're at it, there are a dozen or so other parameters which could
reasonably be set by command-line options.
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Comment (by hamish):
patch attached to add transparency, compression, and background color
options to r.out.png. Patch is vs 6.5svn.
* I'm not sure how useful bgcolor= is, as I'm not sure how often "set" is
likely to return no-color from G_lookup_raster_colors(), or really what
triggers that to be set==0. Or should bgcolor= override the color table's
"nv" color for NULL cells when there's no alpha channel? Is "set" like the
default("*") lesser used rule in the color tables?
* the pointer for G_is_null_value() is specified in a rather raw way.
Ideas for improvement are welcome.
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Comment (by glynn):
Replying to [comment:2 hamish]:
> patch attached to add transparency, compression, and background color
options to r.out.png. Patch is vs 6.5svn.
>
> * I'm not sure how useful bgcolor= is, as I'm not sure how often "set"
is likely to return no-color from G_lookup_raster_colors(), or really what
triggers that to be set==0. Or should bgcolor= override the color table's
"nv" color for NULL cells when there's no alpha channel? Is "set" like the
default("*") lesser used rule in the color tables?
r.out.png shouldn't write the background colour into the image data; it
should just pass it to png_set_background(). If the image has an alpha
channel or transparent colour index but the reader wants an opaque image,
the PNG library overlays the image on the background colour.
The "set" value is 0 if the default colour was used, 1 if a colour was
found for the cell's value (including null; the null value colour is
always defined).
If you want to write an RGB image (no alpha), ignore the "set" value and
the bgcolor= option, and just write exactly what G_lookup_raster_colors()
returns.
If you want to also write an alpha channel, there are two independent
options: whether to make null cells transparent and whether to write cells
with no defined colour (set == 0) as transparent. In all cases, the RGB
channels should still contain exactly what G_lookup_raster_colors()
returns.
> * the pointer for G_is_null_value() is specified in a rather raw way.
Ideas for improvement are welcome.
Arithmetic on a void pointer is undefined (gcc supports it as an
extension). Use:
{{{
size_t rsize = G_raster_size(rtype);
...
G_incr_void_ptr(voidc, col * rsize);
}}}
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Comment (by hamish):
> png_set_bKGD()
changed to use that in r41241, but I'm still getting a segfault. confused
by the layers of structs and `^usage`.
Hamish
ps- what does r.in.png do which r.in.gdal doesn't? is PNG a flexible
enough format to help with the 6-7 raster format transition | grass-gdal
driver plugin | r.external ?
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Comment (by glynn):
Replying to [comment:6 hamish]:
> > png_set_bKGD()
>
> changed to use that in r41241, but I'm still getting a segfault.
confused by the layers of structs and `^usage`.
The (pointer) variable isn't being initialised. Use a structure and pass
its address:
{{{
png_color_16 background_color;
background_color.red = (png_uint_16)def_red;
background_color.green = (png_uint_16)def_grn;
background_color.blue = (png_uint_16)def_blu;
png_set_bKGD(png_ptr, info_ptr, &background_color);
}}}
> ps- what does r.in.png do which r.in.gdal doesn't?
Provides more options, e.g. gamma correction, conversion to float. Also,
by default it imports the raw values rather than expanding to bytes.
> is PNG a flexible enough format to help with the 6-7 raster format
transition | grass-gdal driver plugin | r.external ?
#967: r.out.png: respect TRANSPARENT and COMPRESSION enviro vars
--------------------------+-------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: enhancement | Status: closed
Priority: normal | Milestone: 7.0.0
Component: Raster | Version: svn-trunk
Resolution: fixed | Keywords: r.out.png
Platform: All | Cpu: All
--------------------------+-------------------------------------------------
Changes (by hamish):
* status: new => closed
* resolution: => fixed
Comment:
done in devbr6 and trunk. thanks
qiv 2.1~pre12-5 64bit still goes a bit nuts with the transparent
background, but I'm 99% sure that's a qiv bug and not the bit-depth etc
being set wrong.
