How to replace just pure black by a very dark purple ?

[willyke]

Hi there ! 

I'm Willy Kedziora from France and I need some help to something quite... impossible to do for me. 

I'm in love with ancient painting and I know that they never used pure black, while they conserve others colors.

For exemple, I would like to replace only black parts ( not the middle black or shadows ) but I can't find the solution. There are always purple in my shadows.. 

Anybody to solve this ? 

Thank you by advance. 

Best regards

[dj_paige]

Solution is to use Photoshop.

[willyke]

Yep indeed... 

It will be so ... cool to create a preset in photoshop that works in the lightroom developpment module... 

But, thank you for your answer 🙂

[hanomanob]

In Lightroom Classic you can intersect two masks, on for Luminance (dark color) and on for Color (use the pipette).

[richardplondon]

Another option besides a Masks selection could be: globally adjusting with RGB point-curves within the Tone Curve panel. Or, using the global Grading panel maybe - with the darks selectivity pushed right down.

I am not so sure Grading, nor any other hue manipulation, can have visible effect on a really deep black. But Tone Curve can include a lifting-up of even zero luminance, to a lighter tonality which is capable of showing an effect from changing hue.

Of course true Black cannot show any colour; its red, green and blue components being all zero. And something very close to black is scarcely able to.