EDIT i was planning to make 1 filter i ended up with 5
well once you got how they work you may even don't need anymore it is very easy doing the same manually

But was not easy found how to add back color for most of them:
it is not obvious why but i may assure that filters that create solid black shadows and outline (as Stamp , Charcoal and Dither) can't just recover the color for the original...well they may but results would look awful!!

the trick is simplify the colors from the original the same solid black that would make look awful the composition merge nicely with posterized (or quantized, index) colors, even better if the colors may be smoothed and faded

So here i experimented a similar trick,but with some variants on 5 the Gmic BW filters, i found the results encouraging i think there is still a lot of space for improvements

Some will require patience (as found out how to eliminate some undesirable options from Charcoal without breaking it)
others may just come from your suggestions

well have fun...Maybe are not perfect but i believe all 5 filters may be quite fun to use

####################################################################
The cheaper trick to cartoonize a image but with a added twist :

The filter create a duplicate and apply "threshold " ,convert the image to fully black and white pixels, automatically or with user input
the twist is recover the color from the original but as they are the effect would be horrible, they must be simplified

So the original is quantized (similar to posterized )and optionally smoothed to give color more adapt

The final image combine the black pixel from threshold with the color from the original, quantized and (optionally smoothed )

##############################################################

#@gimp Cheap Cartoonist : gimp_colorstamp, gimp_colorstamp_preview(0)
#@gimp : note = note ("BW module,analog to "Stamp"filter")
#@gimp : sep = separator()
#@gimp : Auto-threshold = bool(1)
#@gimp : Threshold = int(50,0,100)
#@gimp : sep = separator()
#@gimp : note = note ("Color module")
#@gimp : Activate Color module= bool(1)
#@gimp : Quantize Colors =int(20,2,255)
#@gimp : Color Smoothness = float(2,0,20)

#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical")
#@gimp : sep = separator(), note = note("<small>Authors : <i>PhotoComix , Antaron, Mahvin, David Tschumperl&#233;</i>. Latest update : 2011/12/12.</small>")

gimp_colorstamp :

-repeat @# -l[$>] -split_opacity -l[0]

--norm
-if $1 -otsu[-1] 256 -else -t[-1] $2% -endif
-n[-1] 0,255
-apply_curve[-1] 1,0,0,101,33,170,229,255,255
-if {$3==1} -quantize[-2] $4 -to_rgb -blur_xy[-2] $5,$5
-gimp_compose_darken 1,0 -endif
-endl -a c -endl -done

gimp_colorstamp_preview :
-gimp_split_preview "-gimp_colorstamp ${1--2}",$-1

###########################################################

just a wip i am trying to make a ...less cheap version using Charcoal instead then Stamp, but i have problem to simplify the
Charcoal code removing all that unnecessary options (unnecessary for the color filter i wish ) that would confuse the interface and seldom give good results ...but anyway here a wip version

#####################################################################

#@gimp Flying Cartoonist 2: gimp_flyingcartoonist2, gimp_flyingcartoonist2_preview(0)
#@gimp : Granularity = int(65,0,800)
#@gimp : Lowlights crossover point = int(70,0,255)
#@gimp : Highlights crossover point = int(170,0,255)
#@gimp : Boost contrast = bool(0)
#@gimp : Resize image for optimum effect = bool(1)
#@gimp : Add chalk highlights = bool(0)
#@gimp : Minimal highlights = int(50,0,255)
#@gimp : Maximal highlights = int(70,0,255)
#@gimp : Invert background/foreground = bool(0)
#@gimp : Quantize Colors = float (20,2,255)
#@gimp : Color Smoothness = float (2,0.5,30)
#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical")
#@gimp : sep = separator(), note = note("<small>Author : <i>David Tschumperl&#233;</i>. Latest update : <i>2011/03/17</i>.</small>")
#@gimp : note = note("<small>Inspired from the Charcoal script by <i>micomicon</i> :</small>")
#@gimp : link = link("http://registry.gimp.org/node/25078")
gimp_flyingcartoonist2 :
-repeat @# -l[$>] -split_opacity -l[0]
--gimp_charcoal $1,$2,$3,$4,$5,$6,$7,$8,255,255,255,0,0,0,$9
-quantize[-2] $10
-to_rgb -blur_xy[-1] 0.8,0.8 -blur_xy[-2] $11,$11 -gimp_compose_colordoping 1,0
-endl -a c -endl -done

gimp_flyingcartoonist2_preview :
-gimp_split_preview "-gimp_flyingcartoonist2 ${1--2}",$-1

#################################################################

And this is Posterized Dither





#@gimp Posterized dithering : gimp_pdithered, gimp_pdithered_preview(0)
#@gimp : Gamma = float(1,0.01,5)
#@gimp : Contrast = float(1,0,4)
#@gimp : Brightness = float(0,-255,255)
#@gimp : Smoothness = float(0,0,10)
#@gimp : Quantize Colors = int(20,2,255)
#@gimp : Smooth Colors =float(1,0,30)
#@gimp : Mixer Mode = choice( "Color Doping", "Darken","Soft Light","Grain Merge", "Multiply","Value")
#@gimp : Color Intensity =float (1,0,1)
#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical")
#@gimp : sep = separator(), note = note("<small>Author : <i>David Tschumperl&#233;</i>. Latest update : <i>2010/12/29</i>.</small>")
gimp_pdithered :
--apply_gamma[-1] $1 -- 128 -* $2 -+ 128 -+ $3 -blur[-1] $4 -c[-1] 0,255 -ditheredbw[-1]
-quantize[-2] $5 -to_rgb -blur_xy[-2] $6,$6
-if {$7==0} -gimp_compose_colordoping $8,0
-elif {$7==1} -gimp_compose_darken $8,0
-elif {$7==2} -gimp_compose_softlight $8,0
-elif {$7==3} -gimp_compose_grainmerge $8,0
-elif {$7==4} -gimp_compose_multiply $8,1
-elif {$7==5} -gimp_compose_value $8,1 -endif

gimp_pdithered_preview :
-gimp_split_preview "-gimp_pdithered ${1--2}",$-1

Oh well as usually dither doesn't like be scaled down (scaling create moire looking pattern )

and this is the first the Cheap Cartoonist

humm recolor gmic BW filters is too funny, if only the" quantize" control would limit better the avaulable colors..anyway

Colored Pencil And Hard Sketch

###############################################
#@gimp Color Pencil : gimp_cpencil, gimp_cpencil_preview(0)
#@gimp : Size = float(1.3,0,5)
#@gimp : Amplitude = float(50,0,200)
#@gimp : Quantize Colors = int (20,2,255)
#@gimp : Color Smoothness = float(2,0,30)

#@gimp : Color Intensity =float (1,0,1)
#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical")
#@gimp : sep = separator(), note = note("<small>Author : <i>David Tschumperl&#233;</i>. Latest update : <i>2010/12/29</i>.</small>")
gimp_cpencil :
--pencilbw $1,$2 -blur_xy[-1] 0.4,0.4
-quantize[-2] $3 -normalize 0,255 -to_rgb
# -blur_xy[-2] $4,$4
-gimp_compose_grainmerge $5,0

gimp_cpencil_preview :
-gimp_split_preview "-gimp_cpencil ${1--2}",$-1

#############################################################
#@gimp Color Sketch : gimp_colorsketchbw, gimp_colorsketchbw_preview(0)
#@gimp : Amplitude = float(300,0,4000)
#@gimp : Density = float(50,0,100)
#@gimp : Smoothness = float(1,0,10)
#@gimp : Opacity = float(0.1,0,1)
#@gimp : Edge = float(20,0,100)
#@gimp : Fast approximation = bool(1)
#@gimp : Negative = bool(0)
#@gimp : Quantize Colors = int (20,2,255)
#@gimp : Color Smoothness = float(2,0.50,30)
#@gimp : Mixer mode = choice( "Color Doping","Darken","Hard Light","Grain Merge","Lightness","Multiply","Value")
#@gimp : Color Intensity =float (1,0,1)
#@gimp : sep = separator(), Preview type = choice("Full","Forward horizontal","Forward vertical","Backward horizontal","Backward vertical")
#@gimp : sep = separator(), note = note("<small>Author : <i>David Tschumperl&#233;</i>. Latest update : <i>2010/12/29</i>.</small>")
gimp_colorsketchbw :
--blur $3 -hardsketchbw[-1] $1,$2,$4,$5,$6
-if $7 -negative[-1] -endif
-quantize[-2] $8 -to_rgb -blur_xy[-2] $9,$9
-if {$10==0} -gimp_compose_colordoping $11,0
-elif {$10==1} -gimp_compose_darken $11,0
-elif {$10==2} -gimp_compose_hardlight $11,1
-elif {$10==3} -gimp_compose_grainmerge $11,1
-elif {$10==4} -gimp_compose_lightness $11,1
-elif {$10==5} -gimp_compose_multiply $11,1
-elif {$10==6} -gimp_compose_value $11,1 -endif

gimp_colorsketchbw_preview :
-gimp_split_preview "-gimp_colorsketchbw ${1--2}",$-1

how do you put .gmic files in gmic?

As now you just need to refresh the filter in gmic i put the filter yesterday on my source
(you know gmic/about/additional filters check if all source are enabled click apply,,refresh and is done )

are subjected yet to quick chances but all works (i hope to not broken nothing with future changes)

about your question where place a .gmic or gmic file depend from your OS

I can't find Cheap Cartoonist or Flying Cartoonist. I've put a list of the new filters. I've refreshed G'MIC twice.

• Cheap Cartoonist
• Flying Cartoonist
• Posterized Dithering - Artistic
• Color Pencil (There's a Colored Pencils in Artistic - Is that it?)
• Color Sketch - Artistic

you are right O i keep on changing names

just a few minutes to control and i give the updated list

PC they look awesome!!! I love the cars the way they turned out!

@ 0
Cheap/flying cartoonist was replaced by Color Stamp

yes Color Pencil i plan to change a bit because now may be too similar to Graphic Novel used without smoothing

mind that are still Wip, so as example i didn't look yet for good default...and a component let say "posterize"(exactly -quantize or -autoindex) refuse to work as i expect