That's a really common struggle, values can also seem lighter/darker depending on the values that surround them which makes this a pretty tricky challenge! For this drawover I tried to use the value (A) as my threshold between dark and light. It can help to paint a swatch like that off to the side and compare the values to that midtone to see whether it is darker or lighter. Secondly I look at contrast for clues as well. The light edge of the glass has a bigger contrast with the background (1) than the shadow side of the bottle with the background (2). So If I want to try to recreate a closer readability of this reference photo I should have that divide (1) or merge those two shapes (2)! c: Try to squint while looking at your reference picture and see where you find the most contrast/what shapes you see! I hope this helped you out!! c: | Artwod Feedback