G'MIC filter "Sketch"

dinasset · **Posted:** Wed Apr 29, 2015 1:35 pm **(#1)**

A recent post concerning a tutorial (Pencil sketch (old illusion)) by Jamac4k on how to get a nice sketching effect recalled me the existence of an excellent G'MIC plug-in:
- Black&White
- - Sketch
It seems to be very old (relative to G'MIC filters), because last update says December 2010 by David T.
The problem is that is very very slow: to complete a sketch on an image 800x533 (i.e. small considering current std image sizes) it took about 2 minutes.
Hence my simple request to David:
- is it possible to improve dramatically the execution time?
As such that filter can be used only very seldom.
I have some hope, being so old maybe some new technique can improve it.
Many thanks in advance.

For those who do not know this filter yet, here an example (the output has been merged with the original)
(original photo can be found under Deviant Art)

Attachment:

____by_tdum-d7fmxwr_GMIC-sketch.jpg [ 243.34 KiB | Viewed 5515 times ]

due to the slowness, I couldn't afford to try many different presets and choose the best outcome
but IMO it looks good

sallyanne · **Posted:** Wed Apr 29, 2015 2:14 pm **(#2)**

Very good dinasset

dinasset · **Posted:** Wed Apr 29, 2015 2:27 pm **(#3)**

thanks, SallyAnne!
I'm convinced it can be done better, but -as I wrote- the filter is too slow (at least on my PC) to be prone to test and choose among different presets.

Issabella · **Posted:** Wed Apr 29, 2015 3:51 pm **(#4)**

I like your outcome G'mic Sketch, Dinasset. Your attempt is really good. :bigthup

I have liked so much your outcome that I've tried that filter on a photo too, but with no good results.

Then I tried other kind of filter in G'mic and I liked the second outcome.

Odinbc · **Posted:** Wed Apr 29, 2015 5:07 pm **(#5)**

That's a really nice result on the second one Issabella.

jamac4k · **Posted:** Wed Apr 29, 2015 5:18 pm **(#6)**

# dinasset:
I think that Sketch is too hard to get a perfect result. Must be worked in B&W, is better use one orientation, is so difficult obtain the correct stroke lenght, etc. Sometimes we have luck and the result is nice, but others ...

#Issabella:
Pencil portrait was developrd from this tut.
I don't Know why is attributed to Ramón Miranda

dinasset · **Posted:** Thu Apr 30, 2015 1:16 am **(#7)**

Issabella wrote:

I like your outcome G'mic Sketch, Dinasset. Your attempt is really good. :bigthup

I have liked so much your outcome that I've tried that filter on a photo too, but with no good results.

Then I tried other kind of filter in G'mic and I liked the second outcome.

that's the reason why I'm asking David whether he could be so kind to dramatically improve the performances
anyhow, I took you example (not the original, it's not there), resized not to wait until noon, and done my try; here it is:

Attachment:

woman-sketch_DN.jpg [ 146.51 KiB | Viewed 5397 times ]

your second sketch is superb, Issabella!

dinasset · **Posted:** Thu Apr 30, 2015 1:18 am **(#8)**

jamac4k wrote:

# dinasset:
I think that Sketch is too hard to get a perfect result. Must be worked in B&W, is better use one orientation, is so difficult obtain the correct stroke lenght, etc. Sometimes we have luck and the result is nice, but others ...

yes, you're right, one must have the possibility to make many tries....
I'm confident on David....

dinasset · **Posted:** Thu Apr 30, 2015 1:25 am **(#9)**

#Jamac4k

I took another Vanessa's picture and made a GMIC sketch
it's true that it works on B&W, but using the original to merge you get back colours

Attachment:

vanessa-paradis-20080115-363673_GMICsketch.jpg [ 148 KiB | Viewed 5394 times ]

dinasset · **Posted:** Thu Apr 30, 2015 1:28 am **(#10)**

...and this is the look using one orientation, as you suggested

Attachment:

vanessa-paradis-20080115-363673_GMICsketch1o.jpg [ 142 KiB | Viewed 5393 times ]

jamac4k · **Posted:** Thu Apr 30, 2015 2:55 am **(#11)**

# dinasset:

But allways the luck is a unpredictable factor.

With this one I were so luck (ink wash + sketch). No post obviously.

Issabella · **Posted:** Thu Apr 30, 2015 4:06 am **(#12)**

jamac4k wrote:

#Issabella:
Pencil portrait was developrd from this tut.
I don't Know why is attributed to Ramón Miranda

I understand for your words that pencil sketch filter in G'MIC is yours, at least it was based on your tutorial. So congrats for it because it's great and I love the results. :tyspin

Issabella · **Posted:** Thu Apr 30, 2015 5:38 am **(#13)**

More tries.

dinasset · **Posted:** Thu Apr 30, 2015 7:15 am **(#14)**

nice tries, Issabella!
I played a little with your first original (drastically downsized):

Attachment:

cuadros-al-oleo-de-mujeres (9)-base_col1.jpg [ 116.74 KiB | Viewed 2512 times ]

Attachment:

cuadros-al-oleo-de-mujeres (9)-base_col1curv.jpg [ 106.22 KiB | Viewed 2512 times ]

dinasset · **Posted:** Thu Apr 30, 2015 8:39 am **(#15)**

jamac4k wrote:

Pencil portrait was developrd from this tut.
I don't Know why is attributed to Ramón Miranda

In my G'MIC 1.6.2.0 it says
Authors: Jamac4k and David Tschumperlé
Latest update: 12/11/2012

dinasset · **Posted:** Thu Apr 30, 2015 8:42 am **(#16)**

(BTW: also Pencil Portrait is very slow...David, please!)

Ronounours · **Joined:** Jan 03, 2011 **Posts:** 1656

Hello dinasset,
Just to say, I've got some time today, and parallelized the 'B&W Sketch' filter, used also in 'Pencil Portrait'.
It should run faster now.

Attachment:

gmic_sketchbw_p.png [ 639.46 KiB | Viewed 2447 times ]

dinasset · **Posted:** Mon Jun 29, 2015 1:38 pm **(#18)**

These are really good news, for me!
Thanks a lot, David!
I like those filters...

Liz-ard · **Posted:** Thu Aug 13, 2015 12:01 am **(#19)**

Ronounours wrote:

Hello dinasset,
Just to say, I've got some time today, and parallelized the 'B&W Sketch' filter, used also in 'Pencil Portrait'.
It should run faster now.

Attachment:

gmic_sketchbw_p.png

Hello,

Whenever I try to use Pencil Portrait, I can't even get a preview (I get "preview timeout"). I tried running it anyway, but it was taking so long I just stopped it. I'm using G'mic 1.6.5.1. on Windows 8.1 (64 bit). help!

dinasset · **Posted:** Thu Aug 13, 2015 8:58 am **(#20)**

#Liz-ard
how big is your photo?