PBR Albedo Validation and Unity's Colorpicker

Unity Engine
1

I am wondering how to translate Unity’s colorpicker colors into valid PBR albedo colors. The color picker is in RGB(or HSV with values from 0-255) for non hdr. Can i assume that the [HDR] attribute for colors in shaders give the right values? The hdr colorpicker has brightness (HSB?), while the albedo validation in the sceneview mentions luminance. Is this a one to one translation? Do i need to consider some Gamma/Linear conversion?
Also does using the [HDR] attribute come with a performance cost?

Thanks!

2

Is there a tutorial somewhere about the albedo validation? Who from unity could i ping? I am confused. The numeric values in the color pickers don’t match with the luminance from the validation.