CMYK Halftone Effect with empy dots

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myspacee
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Joined: 2007-06-14T02:09:35-07:00

CMYK Halftone Effect with empy dots

Post by myspacee » 2019-02-13T04:53:29-07:00

Hello,
fascinating by this : https://imgur.com/gallery/4mux7bJ
i'm asking how they made CMYK painting by hand. I think they are cheating.

Image

Is possibile to use IM to 'convert' an image to CMYK Halftone Effect but where dots are empty ?
(only edge of a circles are considered)

In this way i can print the image on canvas using a normal in-store printing technique,
then pass by hand every dots respecting CMYK sequence.

Thank you for reading,
m.

myspacee
Posts: 153
Joined: 2007-06-14T02:09:35-07:00

Re: CMYK Halftone Effect with empy dots

Post by myspacee » 2019-02-13T10:36:22-07:00

Hello,
found something related in this old post : http://www.imagemagick.org/discourse-se ... 754#p70754
But i'm not able to adapt old Linux syntax to last windows IM build.

Can you help me ?

thank you,
m.

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fmw42
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Re: CMYK Halftone Effect with empy dots

Post by fmw42 » 2019-02-13T10:43:25-07:00

see https://imagemagick.org/Usage/windows/

remove the \ from the \( ... \)
change the end of line \ to ^

myspacee
Posts: 153
Joined: 2007-06-14T02:09:35-07:00

Re: CMYK Halftone Effect with empy dots

Post by myspacee » 2019-02-13T12:13:37-07:00

Thank you for reply fmw42,
can't solve all issue (and my limits).

In 2010 you reply https://www.imagemagick.org/discourse-s ... =1&t=17389 to user that ask how create B/W Halftone Dither.
The result is similar to goal i want reach :
Image

In above image the dots are exactly what i want (missing negative effect).
I don't know if the right way is to split image to 4 CMYK greyscale files, then treat them like b/w image, apply B/W Halftone Dither
giving the angles of the offset printing halftone and at least rejoin.

As idea, can works ?
(I'm fascinated by the idea of ​​turning an computer image into a real object)

Thank you for your time,
m.

myspacee
Posts: 153
Joined: 2007-06-14T02:09:35-07:00

Re: CMYK Halftone Effect with empy dots

Post by myspacee » 2019-02-13T13:09:41-07:00

Hello again sorry for hammering.

Find CNC software that does exactly what i need http://jasondorie.com/page_cnc.html
You can apply also angle to emulate four color and then join them.

Program take an image and create BIG b/w images composed by dots.

If possibile, can you post command to :
- change black dots color into Ciano, Magenta, Yellow.
- 'reduce' the intensity (TINT) of the dots color
- create PNG with white as trasparent color
- command to join 4 files back

Thank you,
m.

snibgo
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Re: CMYK Halftone Effect with empy dots

Post by snibgo » 2019-02-13T13:43:58-07:00

See the examples at http://www.imagemagick.org/Usage/quanti ... red-dither , also my own Lithographic effects.

We can separate a CMYK image, apply an angled dither to each image, and re-combine. (We do the "angled dither" by rotating the image, dithering, then rotating back.) Windows BAT syntax:

Code: Select all

set OD=-ordered-dither c7x7w

%IMG7%magick ^
  toes.png ^
  -colorspace CMYK ^
  -channel CMYK ^
  -separate ^
  +adjoin ^
  odc-%%d.miff

%IMG7%magick ^
  odc-0.miff ^
  +distort SRT 1,15 ^
  %OD% ^
  +distort SRT 1,-15 ^
  -crop 267x233+0+0 ^
  +repage ^
  odc-out0.miff

%IMG7%magick ^
  odc-1.miff ^
  +distort SRT 1,75 ^
  %OD% ^
  +distort SRT 1,-75 ^
  -crop 267x233+0+0 ^
  +repage ^
  odc-out1.miff

%IMG7%magick ^
  odc-2.miff ^
  %OD% ^
  odc-out2.miff

%IMG7%magick ^
  odc-3.miff ^
  +distort SRT 1,45 ^
  %OD% ^
  +distort SRT 1,-45 ^
  -crop 267x233+0+0 ^
  +repage ^
  odc-out3.miff

%IMG7%magick ^
  odc-out0.miff odc-out1.miff odc-out2.miff odc-out3.miff ^
  -set colorspace CMYK ^
  -combine ^
  -colorspace sRGB ^
  cmyk_dith.png
Image
snibgo's IM pages: im.snibgo.com

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fmw42
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Re: CMYK Halftone Effect with empy dots

Post by fmw42 » 2019-02-13T15:59:04-07:00

I thought my instructions above were pretty simple to follow. Nevertheless, here is the Unix to Windows syntax conversion.
  • remove the \ from the \( ... \)
  • change the end of line \ to ^

Image

Here is the Unix syntax:

Code: Select all

convert birdofparadise.gif -level 0x70% \
-set option:distort:viewport '%wx%h+0+0' \
-colorspace CMYK -separate null: \
\( -size 2x2 xc: \( +clone -negate \) \
+append \( +clone -negate \) -append \) \
-virtual-pixel tile -filter gaussian \
\( +clone -distort SRT 60 \) +swap \
\( +clone -distort SRT 30 \) +swap \
\( +clone -distort SRT 45 \) +swap \
\( +clone -distort SRT 0 \)  +swap +delete \
-compose Overlay -layers composite \
-set colorspace CMYK -combine -colorspace RGB \
birdofparadise_cmyk_halftone_2.png
Image

Code: Select all

convert birdofparadise.gif -level 0x70% \
-set option:distort:viewport '%wx%h+0+0' \
-colorspace CMYK -separate null: \
\( -size 3x3 xc: \( +clone -negate \) \
+append \( +clone -negate \) -append \) \
-virtual-pixel tile -filter gaussian \
\( +clone -distort SRT 60 \) +swap \
\( +clone -distort SRT 30 \) +swap \
\( +clone -distort SRT 45 \) +swap \
\( +clone -distort SRT 0 \)  +swap +delete \
-compose Overlay -layers composite \
-set colorspace CMYK -combine -colorspace RGB \
birdofparadise_cmyk_halftone_3.png
Image



Here is the Windows syntax:

Code: Select all

convert birdofparadise.gif -level 0x70% ^
-set option:distort:viewport '%wx%h+0+0' ^
-colorspace CMYK -separate null: ^
( -size 2x2 xc: ( +clone -negate ) ^
+append ( +clone -negate ) -append ) ^
-virtual-pixel tile -filter gaussian ^
( +clone -distort SRT 60 ) +swap ^
( +clone -distort SRT 30 ) +swap ^
( +clone -distort SRT 45 ) +swap ^
( +clone -distort SRT 0 )  +swap +delete ^
-compose Overlay -layers composite ^
-set colorspace CMYK -combine -colorspace RGB ^
birdofparadise_cmyk_halftone_2.png

Code: Select all

convert birdofparadise.gif -level 0x70% ^
-set option:distort:viewport '%wx%h+0+0' ^
-colorspace CMYK -separate null: ^
( -size 3x3 xc: ( +clone -negate ) ^
+append ( +clone -negate ) -append ) ^
-virtual-pixel tile -filter gaussian ^
( +clone -distort SRT 60 ) +swap ^
( +clone -distort SRT 30 ) +swap ^
( +clone -distort SRT 45 ) +swap ^
( +clone -distort SRT 0 )  +swap +delete ^
-compose Overlay -layers composite ^
-set colorspace CMYK -combine -colorspace RGB ^
birdofparadise_cmyk_halftone_3.png

If in a bat file, double the % to %%

I have brightened them by adding -level 0x70%

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fmw42
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Re: CMYK Halftone Effect with empy dots

Post by fmw42 » 2019-02-13T17:27:39-07:00

Here is perhaps a better one, by making the K channel all black.

Code: Select all

convert birdofparadise.gif  \
-set option:distort:viewport '%wx%h+0+0' \
-colorspace CMYK -separate null: \
\( -size 3x3 xc: \( +clone -negate \) \
+append \( +clone -negate \) -append \) \
-virtual-pixel tile -filter gaussian \
\( +clone -distort SRT 60 \) +swap \
\( +clone -distort SRT 30 \) +swap \
\( +clone -distort SRT 45 \) +swap \
\( +clone -fill black -colorize 100 -distort SRT 0 \)  +swap +delete \
-compose Overlay -layers composite \
-set colorspace CMYK -combine -colorspace RGB \
birdofparadise_cmyk_halftone_3b.png
Image

myspacee
Posts: 153
Joined: 2007-06-14T02:09:35-07:00

Re: CMYK Halftone Effect with empy dots

Post by myspacee » 2019-02-14T03:36:13-07:00

snibgo, fmw42,
thank you both.

Different solutions and I need some tuning to go on print on 'real thing', but it's incredible.

Thank you again,
m.

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