Color Separation?

[rich2005]

Quote:...Should transparency be on at any point?

Only for the "fake - might look like this printed"
If you are using a recent Gimp 2.10 then the Colors > Color to Alpha filter automatically adds an alpha channel (older Gimp 2.10 needed an alpha channel adding before Color to Alpha. That is, Layer > Transparency > Add Alpha Channel))

[zodiakteez]

(07-19-2022, 05:24 PM)rich2005 Wrote:

Quote:...Should transparency be on at any point?

Only for the "fake - might look like this printed"
If you are using a recent Gimp 2.10 then the Colors > Color to Alpha filter automatically adds an alpha channel (older Gimp 2.10 needed an alpha channel adding before Color to Alpha. That is, Layer > Transparency > Add Alpha Channel))

Good afternoon,  

I am using GIMP 2.10.32 (version 1)

I tried the process and I am missing something or messing up the steps, first at the start when I do the step (color ---> invert) the background changes from transparent to black(your background is white)
I completed the remaining steps for each CMYK color.
In you video you are able to produce only the black parts of the image next to transparent background I can not my background is black
When I went to the fake-might look like this step, the first thing that happens for me is when I do the color drop, the entire image(background and image get covered in the color) obviously this is incorrect.

Any help here on what I seem to be doing wrong is grateful.

Thanks.

[rich2005]

I do not know what you are doing. Looking at your screenshot, the subject looks ok.
Background removed and replaced with white. Starting from that

Colours -> Components -> Decompose (to CMYK) gives a greyscale image with "All black background" layers.
For each layer
Colours -> Invert gives a greyscale with a "all white background"

[zodiakteez]

(07-20-2022, 04:35 PM)rich2005 Wrote: I do not know what you are doing.  Looking at your screenshot, the subject looks ok.
Background removed and replaced with white.  Starting from that

Colours -> Components -> Decompose (to CMYK) gives a greyscale image with "All black background" layers.
For each layer
Colours -> Invert gives a greyscale with a "all white background"

I have attached some images to show my results which are not consistent or successful.

first image shows one of the CMYK colors did not achieve the correct background.
The second shows one with the correct background....overall the CMYK and Black final came out with transparent BG
The middle two colors did not......(I dont think the colors are the issue I must be doing something incorrect)
The third image shows before I do the color drop
The last image is the result of the color drop and what happened.

[rich2005]

Are you happy with the procedure for creating screenprinting masks in the first place ? For photo-emulsion masks the aim is a black shape on a white background.

You have your decomposed image, with CMYK layers.
Invert gives a grey foreground and a white background.
For screenprinting using photo-emulsion material you need a black and white mask. Various ways to get that, Colours -> Threshold on each layer is one way.

--------------------
To see what it might look like printed using emulated screenprinting methods.

This is the bit you are missing, you might as well do it now. Decompose gives a greyscale image, change it to RGB Image -> Mode -> RGB
Remove the white using Colours -> Color-to-Alpha
Lock the alpha channel (the transparency) using the alpha lock top of the layers dock for each layer.
Bucket fill using the appropriate colour. (note your cyan is not cyan. Cyan is 0% red / 100% green / 100% blue )

Your photograph is not going to look wonderful, lots of solid blocks of colour.

I have the feeling you are going round in circles.