Seeing a single value is hard. Seeing whether one area is lighter or darker than another is a skill you can train — and it is what painters do constantly, in the studio and outdoors. This lesson covers simple tools and a step-by-step comparison method we use in foundation drawing at Art Tutor Hanoi.
Why compare in pairs
Instead of guessing “value 6” for every shape, you anchor a few reference areas (often the lightest light and darkest dark), then compare everything else relative to those. With seven major shapes you might make up to twenty-one pairwise checks — in practice you focus on shapes that are close in value.
Make a value finder
A value finder isolates two areas so hue does not distract you.
Three-hole version
Paint an old card or mat board middle gray. Punch three holes. Hold it up so each hole frames a different area; squint to see which spot is lighter. Paint the card a uniform gray — a colored card will bias your judgment.
Slit version
Cut a narrow slit instead of holes. Slide it across skies, water, or walls to read slow value transitions without naming the objects.
Tools to avoid
- Red transparent “value viewers” — reds read lighter than they are and skew comparisons.
- Slotted printed value charts outdoors — the chart and your subject are rarely in the same light; the comparison fails in shade vs sun.
A black mirror (or phone screen turned off) can also help: hold it beside your subject to see simplified reflections in black and white.
Four-step comparison sketch
- Squint and sketch seven or fewer big value shapes — ignore small details.
- Mark your lightest and darkest shapes with numbers (1 = dark, 9 = light is a common convention).
- Compare every pair that might be close; adjust numbers until the order is correct, even if the exact numbers shift.
- Use the sketch as field notes for a studio painting or a charcoal study.
Two adjacent objects with the same value count as one shape, even if their colors differ.
Try it at home
Exercise — Identifying values
Choose a still life or a view from a window. Make six quick outline maps (about ten minutes each) with value numbers only — no shading. Photograph the scene, convert to grayscale, and check whether your ranking matches. Beginners: six sketches; if you already draw regularly, aim for a dozen.
Common questions
- Do I need exact numbers? — Ranking light vs dark matters more than perfect digits.
- White paper indoors looks white but is darker than sunlit snow — trust comparisons, not memory.
- Next lesson — 1.4 shows how to posterize photos to check your value plan.
Send a value map for critique
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