[Tuxpaint-devel] Gimp script-fu to help create stamps

[Pere P. i C. <pe...@fo...>]

Hi all!

When porting the Childsplay images to Tuxpaint it comes clear to me that
the stamp creation should be as automatized as possible.

I've begin to learn the gimp script-fu language and come with this
script:
http://fornol.no-ip.org/linux/tuxpaint/scripts/mktpstamp.scm

It is developed under gimp 2.3.18 ,and don't work under stable 2.2.XX
series. It is work in progress and have some questions that I ask as I
comment the script.

You can follow my comments about editing the image by looking at
http://fornol.no-ip.org/linux/tuxpaint/scripts/Dumper_scaled.xcf
It is a 4.2MB dowload, the original image is about 20MB and I've not
putted on the web.

I use the script in this way:

Put the script in .gimp-2.3/scripts directory and chmod 755 it
If gimp is already started, go to Extensions->Script-fu and reload the
functions.

Prepare the image as in the advanced stamps howto.
Hide the topmost layer.
Now add a wite layer on top of WIP layer. Select transparency about
30%-60% for this layer depending on subject.
Outline in this layer the subject you want with the 1 pixel brush (hold
the shift key and go clicking around the edge, the more curve, the more
join the clicks.)

Add a new transparent layer on top of Outline.(Working1)

Go to Outline, select by neighbour the interior of outline, go to the
WIP layer, CTRL+C to copy, Go to Working1, CTRL+V to paste, CTRL+H to
attach.

Duplicate Working1<->Working2 as this we have a backup.


Hide all layers except Contrast ones and Working2, edit the image in
Working2.

Add a layer mask on Working2 using the alpha value (not transfering it,
just use it). Let the mask as is, antialias should be done by the
script.

Now check the edges of subject, there seems to be some weird effects
caused by light. Duplicate Working2<->Working3, hide Working2. (a new
backup)
In Working3 select by color transparent, grow the selection by 1,2 or 3
pixels at most, CTRL+X to delete those pixels, now you should get ride
of most of light effects on egdes of subject. Finish editing the edge if
there rest some light effect.

Now we have a subject lying on a transparent layer and a sharped mask.

Set the image in this layer to edit (not the mask) and run the script.
Script-fu->alchemy->mktpstamp

You will be prompted by several things:

Runs: The script will expand the edges of the subject 5 pixels around
per run, so if you want the edge be expanded 30 pixels you should put 6
here. BTW this should be calculated from the original and final sizes,
so a question is How many pixels should be expanded in order to avoid
problems with edges when tuxpaint scales down?

Use the current foreground color: The transparent space left by the
expansion of the edge will be filled with the average of color find at
center of the image. If the subject has a hole there, this will not be a
right average color for the subject. Selecting a right foreground color
before running the script and checking this will do better results.

Scale and max final size: If you want to scale check it, set the maximun
size you want for the final image. If scale is not set the final size
will not be used. BTW What size is a good default?

Base filename without extension: .png will be appended

Close the auxiliar image when done: Uncheck to see what is resulting and
for debugging purposes.(The undo button will work)

Create .txt file: If you want to create the companion .txt files coming
with stamps. Name will be base filename with appended .txt

Text to put: The descriptive text of the stamp

Create .dat file: same as for .txt file

Some values for .dat file. Here I have some questions:

tintable and colorable are conflicting one with other?

Scale field is right as say 40%. Is it allways right as 400% ?


Click on OK when you are done, the script will begin its work.

First it will expand the edge of the image using the pixels on the edge
of the subject. To do this, each run it copies and displaces around the
layer on all pixels in a 5 pixels circle from exterior to interior (this
implies the creation and destruction of 49 layers per run).

Now the image will be displayed

Second will fill the rest of the image using a calculated color or the
foreground one.

Scale if required. I've seen some strange effects using lanczos, now I
use cubic interpolation in gimp->edit->preferences->Option Tools->Scale
interpolation. May be it should be hardcoded in the script.

Blur the mask --> antialias. We should check if it is enouth or needs
more love and may be make it optional for people wanting to hand edit
the mask. BTW scaling blurs the mask as well.

Save as png and keep the values of transparent pixels
close the image if required
create .txt and .dat if required


You can see the results of applying the script over the above xcf at
http://fornol.no-ip.org/linux/tuxpaint/scripts/dumper.png or .txt
or .dat


What do you think about?
Can it be usefull?
Other comments?

Thanks
Pere