Gimp-Forum.net
one bit transparency - Printable Version

+- Gimp-Forum.net (https://www.gimp-forum.net)
+-- Forum: GIMP (https://www.gimp-forum.net/Forum-GIMP)
+--- Forum: General questions (https://www.gimp-forum.net/Forum-General-questions)
+--- Thread: one bit transparency (/Thread-one-bit-transparency)

Pages: 1 2

RE: one bit transparency - bitrat - 11-07-2022

I think I now have all the steps I need.  Thank you everybody.  Big Grin

Somewhat away from my original question and not my specific goal, but key to it if anyone else is interested...

To simulate CMYK process* using GIMP and Inkscape:

In GIMP:
  • decompose RGB image to CMYK layers
  • create image mask for each layer and initialise with Grayscale copy of layer
  • convert layers back to RGB
  • flood fill each layer with its process colour (select cmyk with the palette selection buttons above sliders)
  • turn off visibility for other colours and export a png for each layer
In Inkscape:
  • import the png's
  • create separate layers for each process colour
  • set each layer's Blend mode to Darken or Multiply
  • move each png to it's corresponding layer
  • align the images
  • ...and viola!
Finally, to disable antialiasing for pixel level control, set Image Rendering to crisp-edges in Object properties.

* Please note, not recommended for prepress!

RE: one bit transparency - denzjos - 11-07-2022

The whole option was to simulate a CMYK process. Nice workflow. I get it, but  I don't understand what you mean by 'crisp'. In Inkscape 'Image Rendering' I only find this options : auto, optimiseQuality, optimiseSpeed. In Inkscape I still don't see 'crisp' bounderies (see example done in gimp):

[attachment=8979]

RE: one bit transparency - bitrat - 11-07-2022

(11-07-2022, 09:51 AM)denzjos Wrote: The whole option was to simulate a CMYK process. Nice workflow. I get it, but  I don't understand what you mean by 'crisp'. In Inkscape 'Image Rendering' I only find this options : auto, optimiseQuality, optimiseSpeed. In Inkscape I still don't see 'crisp' bounderies (see example done in gimp):
Thanks.  Smile

Is this crisp edges?  No. In addition to the options you list, mine has crisp-edges and pixelated.

I'm using an AppImage of Inkscape v1.0 (4035a4f, 2020-05-01) ...which seems like a weirdly low number, but that's what the about dialog says...

I'd be interested to know what version you're using.  Nothing worse than relying on a feature in an app then finding it's been dropped by the developers!

You could try upgrading or downgrading, as the case may be..

RE: one bit transparency - bitrat - 11-07-2022

Exported a 20x20 1-bit BMP from GIMP.  It has a 45 rotated square in the middle and a pixel in each corner.

Here it is in bash...


Code:
tail -c +62 1bit-diamond-20x20.bmp | hexdump -v -e '/1 "%u\n"' | xargs -I {} echo -e "obase=2\n{}" | bc | xargs printf "%8s" | sed 's/[0 ]/_/g' | while read -n 32 row ; do echo "$row" ; done
__________1111111111111111______
__________1111111111111111______
________11111111111111111111____
________11111111111111111111____
________111111111__111111111____
________11111111____11111111____
________1111111______1111111____
________111111________111111____
________11111__________11111____
________1111____________1111____
________1111____________1111____
________11111__________11111____
________111111________111111____
________1111111______1111111____
________11111111____11111111____
________111111111__111111111____
________11111111111111111111____
________11111111111111111111____
__________1111111111111111______
__________1111111111111111______


RE: one bit transparency - denzjos - 11-08-2022

@bitrat, I installed the current stable inkscape version and now I find crisp-edges and pixelate in the object properties. The version I used was 0.9 Blush