A practical way to narrow down hair colors

I tried taking a few phone photos to understand my undertone before changing my hair color. The same face looks warmer by a window in the evening and cooler under a bright bathroom light. The shifting colors make a neat online result hard to trust on its own. The starting point is light brown hair, so a small tonal change would be enough. I found skin tone analysis while looking for a way to compare images, but I still need a sensible way to use the information. The real goal is a wearable shade in everyday light, not a perfect match to one edited image. I can take pictures with the same plain background, no beauty filter, and my hair pulled away from my face. Should I keep the lighting and clothing simple when I compare possible shades? I am also thinking of holding a few fabric colors near my face rather than deciding from a single photograph. A stylist could then compare actual hair swatches against my skin and natural roots. That would give us something concrete to discuss instead of trying to prove that an app assigned the right season. I plan to compare the samples without editing the pictures afterward. If your photos gave conflicting undertone clues, how did you decide whether to try neutral or cool hair color?