Re: [Gimp-developer] Need help with Python plugin exporting to raw file (using Gimp 2.9)

["Joao S. O. Bueno" <gwidion gmail com>]

Hi Alek_

it turns out that the Python bindings for GIMP had not been updated to
deal with higher precision images as of yet.

Don't despair - since you had built GIMP master, this is as good time
as any to get it going. :-)

You can get to know the image precision (and even set it) thorugh the
PDB, though, with a call to:

pdb.gimp_image_get_precision

Now - for the actual business: I think there are two ways to go - one
short term, with
a "get" and "set" buffer method on Python drawables that will just
copy the inner image data
and make it available in a Python array. That would suffice for most
needs like yours, I guess.

The other, longer term and proper way, is to write calls to get the
proper GEGL Buffer objects
in Python, using GEGL Python bindings - that will allow the use of any
of GEGL's operations
on GIMP Image data and commit it back - but it will also require the
python-gegl package.

Those bindings are currently living in my personal repo, and  could
work for you right now, as they do allow access to the buffer data -
but you have to build GEGL with the extra "--enable-introspection"
switich to get then going.
(http://github.com/jsbueno/python-gegl )

But -- let's focus in enabling one to get the high-depth pixel
contents from GIMP without need for those for now.
Feel free to poke me again in 24 hours if there are no news on this subject.

  js
 -><-


On 19 February 2015 at 23:06, Alek _ <spectatoe outlook com> wrote:
> I'm using Gimp 2.9 experimental build, which I downloaded from
> partha.com, to specifically have edit ability with 16-bit per channel
> images.  I originally posted in gimpforums.com and was told I should try here.
>
>
>
> I'm trying to write a Python plugin to export an image as a raw file
> (just data, no header).  The current option to export as raw image data
> (File -> Export as -> Raw image data) seems to only support writing out as 8-bit even when the image 
> precision
>  is greater than 8-bit.  So I wanted to write a plugin so I could export
>  my 16-bit per channel image to a raw file with the 16-bit data
> preserved.
>
> My image is a 16-bit grayscale 3x3 image with a checkerboard pattern of alternating white and black pixels.
>
>
>
> I used the sample script 'test-discolour-layer-v4.py' from http://registry.gimp.org/node/28124
>  as a guide on how to iterate through every pixel.  I have some
> questions and ran into some problems.  What I have so far can be seen here (http://pastebin.com/U49VZYVT).  
> It just iterates through the pixels and outputs values to the
> error console.
>
>
>
> 1. How do I query for the precision?  That is, I want to know if the
> current image is 8-bit gamma integer, or 16-bit linear integer, or
> something else.  I looked at the image object's attributes and didn't
> find anything.
>
>
>
> 2. When I get the pixel value from srcTile[x,y], the value is always
> 8-bit.  With the white pixels, the value should be 65535 but I got 255.  How do I get the
> proper value?  When I use the Color Picker tool with info window, it says 65535 for white.  How do I get 
> that value?
>
>
>
> 3. My code creates a new layer from visible and then queries the pixels from that.  In my image, all values 
> returned are 255 even for the black pixels.  When I put my checkboard pattern on the Background layer and 
> query that layer, I get correct values (though in 8-bit).  For any other layer other than Background, the 
> values are always 255.  I don't know what I'm doing wrong.
>
>
> Can someone help me or point me in the right direction?
>
> Thanks.
>
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