Need a way to replace all colors by full white still keeping black lines

[Gregory Dubus]

Hi Affinity Apple Mac desktop developper,

I am an artist who makes geometric paintings full of various colors. As I would like to create a colouring book, I have used the adjustment 'Black and white' but it doesn't answer to my needs as, even if the colors disappeared, there are various kinds of white/grey colors whereas I am looking for getting only full white everywhere still keeping the black lines.  I have asked support from the support community and people gave me a few options. The best and easy one is to use the adjustment 'Threshold' and to reduce the % of threshold. In this case, I was able to get full white everywhere but, unfortunately, the black lines ended up with lot of white dots inside which doesn't look really nice (not professional result enough to be able to print nicely).

So, unless you could tell me how to get easily and rapidly full white everywhere still keeping my black lines fully black (possible? How?), could you, please, make a new functionality in Affinity which would answer to my needs? This could allow me to create Art colouring books

I am looking forward to hearing from you soon.

Regards,

Greg.

[walt.farrell]

The discussion still seems to be going on in your original topic.

 

[PaulG]

Given this thread is about changing to White rather than a specific colour, I'm posting the steps that achieve this here instead of the other thread.
 

1. Create a Brightness and Contrast adjustment, don't change anything yet.
2. Create a Threshold adjustment, don't change anything yet.
3. Return to the Brightness and Contrast adjustment
   1. Increase the Brightness until you're left with mostly the black lines. Don't go too far or you might break some of your lines. There will be black dots here and there (a result of the scanning producing irregular colours).
   2. Decrease the Contrast to address black dots
4. Return to the Threshold and with the adjustment's dialog open, pan around your document to look for any remaining black dots inside your shapes
   1. Decrease the Threshold slider until you're satisfied you've removed all the dots
   2. Be careful not to go too far, it'll break the lines, so make small adjustments and keep an eye for broken lines as you pan around looking for dots. Find a balance you're satisfied with
5. This will leave you with very jagged lines
6. Add a Gaussian Blur live filter layer
   1. Increase the radius (a tiny amount should be enough) to take the hard edge off the lines
7. Add a High Pass live filter layer
   1. Set the Blend mode to Linear Light
   2. Increase the Radius to thicken the lines to your where you are satisfied

Using those steps, this is what I ended up with.

 

If you're going to be doing this frequently, you could create a Macro to produce those layers quickly. Then tweak each one to suit the image you're currently working on.

 

[Gregory Dubus]

Thanks Paul G. IO could follow everything until point 7. How to had a hight pass live filter? Can't find it.

Cheers,

Greg.

[Gregory Dubus]

I have found it! Problem fixed. Thanks