How to copy exact same black, grey and whites from a picture and apply these to a color picture?

[Samuel32444149iblm]

Hello everyone!

Im getting really frustrated with an issue, since I cant solve it at all.

Is there a way to "copy" the exact same black, grey and whites from an image and apply it to the an image, that already has colors? I really want these grayscale range, because I want to apply gradients on it.
I tried some stuff like Image →Mode →Grayscale but I always get a different black, grey and white.
I really need the exact same grayscale range from the Picture 1. (Check attachment please). And these black, grey and white I want to apply to Picture 2, which already has colors.

I would be so grateful for any idea!

Sam

[D Fosse]

I've read this four times and I'm still not clear on what you want... 😉

Basically, you can layer them and use either "Color" or "Luminosity" blend mode on the top layer.

However. There's a caveat here. You must make sure all your images have an icc profile embedded, either an RGB profile or a grayscale profile. And in the latter case there's a gotcha.

Grayscale is subject to standard color management just like RGB. Obviously there's no color involved, but each grayscale profile has a specific tone curve (gamma). This will determine which numbers are produced from the visual tone, and this in turn again affects how it will interact when applied to other images. I would recommend Gray Gamma 2.2 if your color images are Adobe RGB, and sGray if your color images are sRGB or P3

But we're not through yet. Desaturating an RGB image just averages out the RGB values. It does not take into consideration that some colors are inherently bright, like yellow, and some are inherently dark, like purple. The result is that yellows turn into a drab and dark gray, and purples appear washed out.

The Lab color model works differently. It takes this into account, by separating the brightness component from the color components. So to get the same visual appearance in terms of tones, convert to Lab first and then desaturate. Then you can convert back to RGB. It's more easy to illustrate than to explain:

[josantgomez]

Gracias a D. Fosse por su explicación, muy interesante y fundamentada. Hablo como profano y así hay que entenderme. Intenté convertir una fotografía en blanco y negro a color mediante los neural filters y no fue posible. Prácticamente me daba un solo color, conviertiéndose en dominante y lo que variaban eran los tonos del mismo. Es posible que también mi inexperiencia con la herramienta contribuyese al fracaso. Luego intenté hacerlo "pintando" la foto. Conocía bien el sitio y los colores. Por tanto buscando en el panel de colores y con herramientas de selección fuí completanto la imagen. El resultado no fue lo bueno que buscaba, pero también puede ser un camino con paciencia. Aparte de lo aconsejado por Foss, buscaría leer algo de cómo se hizo el coloreado de películas en blanco y negro hace unas décadas. Ojalá consigas lo que buscas.

https://www.youtube.com/watch?v=m7GCLV3GP0Y

[c.pfaffenbichler]

Could you please set the Status Bar to »Document Profile« and post meaningful screenshots with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible? 

Is the »grayscale« image actually grayscale or is it a desaturated RGB? 

What are the involved images’ exact Color Spaces?