Bonjour,
Here are some lines of code to modify and copy-paste in G’MIC Gimp to get color points on contours and elsewhere …
-n[-1] 0,255
-blur[-1] 2
-isophotes[-1] 6
{w},{h},1,4
-repeat {{{w}+{h}}/2}
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,255,255,255,255
-point {u(100)}%,{u(100)}%,0,1,255,255,255,255
-done
-and[-1,-2]
-dilate_circ[-1] 2
-sponge[-1] 5
S’amuser avec G’MIC :o)
Some commands I’ve not seen before so had to investigate 
The ‘sponge’ command is random based, which lead me to wonder about other approaches and the possibility of controlling it (range 0 to 1):
example_pointoutline : skip ${1=0.12}
normalize[-1] 0,255
blur[-1] 2
isophotes[-1] 6
100%,100%,1,1
noise[-1] 0.5,1
lt. {$1-0.5}
mul[-1,-2]
_circle 5
dilate[-2] [-1]
rm.
Two problems though; I’ve cheated by using the internal ‘_circle’ command and the distribution won’t be quite like your line method!
Looks like it would make for some cool star renders, samj.
Bonjour,
Thanks for the tests and the filter ‘example_pointoutline’. I enclose a rendering example with a value of 0.2 in G’MIC GIMP.
It’s a good idea to make stars or maybe twinkles. You can give an example of your wishes on an image to see if it is possible to create this.
:o)
@lylejk your idea gave me ideas!
Perhaps a ‘sprite cloud’ or shape average could do this, G’MIC indeed has the means. But what if we use convolution instead?
example_shapecloud : -check ${-is_image_arg\ $1}" && isval(${2=9})"
-repeat $! -pass$1 0 -l[$>,-1]
kw={$2+1-$2%2} r. $kw,$kw,1,1,5 n. 0,1
+gt[0,1] 0 convolve[-2] [-1] -rm.
convolve[0] [1] rm[1] +eq. 0 +[-2,-1] /
-endl -done
Given this, we can continue as follows:
example_staroutline : skip ${1=0.2},${2=11}
normalize[-1] 0,255
blur[-1] 2
isophotes[-1] 6
100%,100%,1,1
noise[-1] 0.5,1
lt[-1] {$1-0.5}
mul[-1,-2]
shape_star ,
example_shapecloud[-2] [-1],$2
rm[-1]
And the output:
Bonjour,
There is a small typo error in the ‘example_shapecloud’ tests.
I enclose the code and an example of this very nice filter in G’MIC GIMP.
:o)
example_staroutline 0.05,10
example_shapecloud : -check ${"is_image_arg $1"}" && isval(${2=9})"
-repeat $! -pass$1 0 -l[$>,-1]
kw={$2+1-$2%2} r. $kw,$kw,1,1,5 n. 0,1
+gt[0,1] 0 convolve[-2] [-1] -rm.
convolve[0] [1] rm[1] +eq. 0 +[-2,-1] /
-endl -done
example_staroutline : skip ${1=0.2},${2=11}
normalize[-1] 0,255
blur[-1] 2
isophotes[-1] 6
100%,100%,1,1
noise[-1] 0.5,1
lt[-1] {$1-0.5}
mul[-1,-2]
shape_star ,
example_shapecloud[-2] [-1],$2
rm[-1]
Interesting! Next assignment would be to do a Tiger God or a cloud Mufasa 
.
Cool stuff; what I actually meant was creating sky starts. Posted a tribute to Stephen Hawkings (link below) for what meant. Even so, like the idea of using any object. As a side note, I used voronoi stipper to place the points which I turned into starts. Added some additional background stars as well.
He's taken his placed among the stars, now.: Retouching Forum: Digital Photography Review
Bonjour
@lylejk
It seems to me that they are flickering and ‘white’ points about the tribute to Stephen Hawking. Thank you for this idea.
@afre
The tiger is the one of the Ghostscript examples. I use it because it is known and its contours are clear.
:o)
It’s an attempt to create stars twinkling but there is surely better.
-n[-1] 0,255
-blur[-1] 2
-isophotes[-1] 6
{w},{h},1,4
-repeat {{{w}+{h}}/10}
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,255,255,255,255
-point {u(100)}%,{u(100)}%,0,1,255,255,255,255
-done
-and[-1,-2]
-i [-1]
-i [-1]
-dilate_circ[-3] 4
-dilate[-2] 10,1
-dilate[-1] 1,10
-blend[-1,-2,-3] alpha
Here is an example of a rendering of Stephen Hawking’s photograph that uses star flickering (rendering needs to be improved).
(source https://i2-prod.mirror.co.uk/incoming/article9569949.ece/ALTERNATES/s615/Stephen-Hawking.jpg )
:o)
-n[-1] 128,255
-to_pseudogray[-1] 5,1,8
-blur[-1] 2
-isophotes[-1] 6
{w},{h},1,4
-repeat {{{w}+{h}}/2}
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,255,255,255,255
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,0,0,0,0
-point {u(100)}%,{u(100)}%,0,1,255,255,255,255
-done
-and[-1,-2]
-i [-1]
-i [-1]
-dilate_circ[-3] 2
-dilate[-2] 6,1
-dilate[-1] 1,6
-blend[-1,-2,-3] alpha
Heard to beat GIMP’s own Sparkle filter. Still, your result looks promising. I took your latest code, then followed it by G’MIC’s morphological filter to squeeze the stars smaller, then ran GIMP’s sparkle preset (random orietation sparkles this time).
@samj @garagecoder Could you please explain the commands a bit more?
– Is there a way to evenly distribute the objects along the contours?
– How do we add the shapes and also make them vary in size and orientation?
Bonjour,
@lylejk
It’s hard to beat Gimp’s ‘sparkles’ filter…
@afre
Here is a commented example and the result
:o)
# normalize the colors between 128 and 255 to obtain lighter colors
-n[-1] 128,255
# get a 'gray' image with a richer gray
-to_pseudogray[-1] 5,1,8
# add blur for richer rendering with the 'isophotes' command
-blur[-1] 2
# to obtain contours according to the luminosite with a transparent background
-isophotes[-1] 6
# create a new image with 4 channels to the dimensions of the current image
{w},{h},1,4
# n loops or n = (width + height) /1.5
-repeat {{{w}+{h}}/1.5} # delete points
# draw a transparent line from the middle of image with a random length
-line[-2] 50%,50%,{u(100)}%,{u(100)}%,1,0,0,0,0
-done
# loops
-repeat {{{w}+{h}}/2} # points on outlines
# draw a white line with a random length
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,255,255,255,255
-done
# loops
-repeat {{{w}+{h}}/5} # points outside the outlines
# put white dots randomly on the image
-point {u(100)}%,{u(100)}%,0,1,255,255,255,255
-done
# 'and' between the 2 images [-1,-2] to obtain a single resulting image
-and[-1,-2]
# 'circular dilation' by 3 pixels
-dilate_circ[-1] 3
Another possibility to have other outlines (experimentation).
-tones[-1] 3
-isophotes[-1,-2] 3
-blend[-1,-2] alpha
-blend[-1,-2] alpha
-mul[-1] 255
-isophotes[-1] 3
{w},{h},1,4
-repeat {{{w}+{h}}/1.5} # delete points
-line[-2] 50%,50%,{u(100)}%,{u(100)}%,1,0,0,0,0
-done
-repeat {{{w}+{h}}/2} # points on outlines
-line[-1] {u(100)}%,{u(100)}%,{u(100)}%,{u(100)}%,1,255,255,255,255
-done
-repeat {{{w}+{h}}/5} # points outside the outlines
-point {u(100)}%,{u(100)}%,0,1,255,255,255,255
-done
-and[-1,-2]
-dilate_circ[-1] 3
-c[-1] 0,255
-to_rgb[-1]
Bonjour,
I grouped ideas from this thread into a G’MIC filter in Lyle Kroll’s folder.
Testing > Lylejk > Point Star Outline
(update filters)
:o)
Edit 20180405
A test :
Thanks for turning this into a filter! Otherwise it was another thing on a very long list of “to do”
