Luminance Processing is a term I’ve been using for the way I’ve started editing my images recently.
I’ve developed some level of reputation among peers with my passion for monochromatic photos. I believe it stems from my interest in chiaroscuro, a painting style that appears to sculpt the highlights from the shadows in a way that holds both a pleasingly soft gradient of tones, and a very strong contrast throughout the image. As a photographer I see the world in monochrome – the colors are often a distraction, where I focus on the play of light and shadow across a scene.
When I want a scene to have more contrast with a natural or even painterly feel, I will add a Black and White adjustment layer, adjust the color luminance sliders as desired and switch the blending mode to Luminance. I can also add curves adjustments while viewing the image in greyscale until it looks pleasing as a monochromatic image, and change the adjustment layers to luminance. The final image will have color as intended, but will have the interesting toning characteristic of strong black and white images.
A final, optional adjustment that helps to achieve the chiaroscuro feeling is to change the black and white adjustment layer from Luminance to Multiply, and adjust the color sliders as desired. The final image is darker with a very stark feeling, but the bright spots can be lifted with further curves or color luminance adjustments for an interesting overall look.