Value, Light, and Form

Value 明度 is lightness and darkness — the backbone of drawing, because we see form as light before we see colour.

• A value scale 明度阶 runs from white through greys to black. Drawing a smooth 9-step scale is the classic control exercise.
• Most beginners draw too light and use too narrow a range. Push the darks so the drawing uses the full scale.
• High-key 高调 drawings use mostly light values and feel airy; low-key 低调 drawings use mostly dark values and feel heavy or dramatic.
• Local value 固有明度 is how light the object's own surface is; lighting is how much light falls on it. Keep the two ideas separate.
• Squint 眯眼 at the subject: squinting removes detail and shows the big value shapes.

One light source creates a predictable pattern of light and shadow. Learn the pattern, and any form becomes drawable.

One light source, six zones: highlight, light, halftone, core shadow, reflected light, and cast shadow

• The six zones: highlight 高光, light, halftone 中间调, core shadow 明暗交界线, reflected light 反光, and cast shadow 投影.
• The core shadow is the darkest band on the form, where the surface turns fully away from the light.
• Reflected light bounces back into the shadow side — but it is always darker than any lit halftone.
• The cast shadow is darkest and sharpest where it meets the object, then softer and lighter further away.
• Shadow edges tell the story: hard edges mean a sharp turn or a cast shadow; soft edges mean a gradual turn.

Rendering 塑造 means building smooth, believable volume — turning flat shapes into spheres, cylinders, and boxes.

• Every complex subject simplifies into basic forms 基本形体: sphere, cylinder, cube, cone. Render those first.
• Work dark-to-light or light-to-dark consistently; jumping around destroys the value structure.
• Blend with intention: a blending stump 擦笔 smooths values, but preserved marks often read stronger than over-blending.
• Keep the lit side and the shadow side clearly separated. Form collapses when halftones creep into the shadow.
• A drawing of white objects (eggs, cups, cloth) is the classic rendering test: all the value comes from light alone.

Chiaroscuro 明暗对照法 ("light-dark") uses strong value contrast for drama — the language of Caravaggio and Rembrandt.

Seurat's conté-crayon portrait is built from soft tone alone, with almost no outline; the rough paper catches the crayon to give velvety greys

• A single strong light against deep shadow pushes the subject forward and sets the mood.
• Tenebrism 暗色调主义 is extreme chiaroscuro: most of the image sinks into darkness while one area blazes.
• Save the strongest contrast for the focal point 视觉焦点 — contrast attracts the eye first.
• Charcoal and ink wash suit chiaroscuro because they reach rich, deep darks quickly.
• Working on toned paper 有色纸 with black and white media makes the light logic explicit.

Notan 明暗构成 is the design of light and dark shapes. A drawing works or fails at thumbnail size, before any detail exists.

Reduce the scene to two or three values: connected value shapes read clearly; scattered spots read as noise

• Reduce the scene to 2-3 flat values. If the pattern still reads clearly, the composition is strong.
• Thumbnail sketches 小稿 (5-8 cm) let you test several value plans in minutes.
• Group your values: many small lights scattered everywhere feel noisy; connected value shapes feel designed.
• Place the darkest dark against the lightest light at the focal point.
• A clear value hierarchy — one dominant value, one secondary, one accent — organises the whole page.

Starting from a toned ground 有色底 lets you draw in both directions: darker with media, lighter with an eraser.

• Cover the paper with an even charcoal or graphite tone, then lift out 提白 the lights with an eraser.
• Subtractive drawing 减法素描 treats the eraser as a drawing tool — pulling light out of dark.
• A kneaded eraser 可塑橡皮 moulds to any shape: dab for soft lights, drag for soft strokes; a hard eraser cuts crisp lights.
• Toned or grey paper gives a ready-made middle value: you add only the darks and the white highlights.
• The mid-tone start forces value decisions early — nothing can hide behind white paper.
• This process is visible experimentation 实验 with materials — exactly what the CED asks you to document.

• Full value range is a score signal. Scorers see weak, grey-on-grey drawings constantly; a confident black-to-white range stands out immediately.
• Get the core shadow and reflected light right — they are what separates students who understand light logic from students who copy photos.
• Include one white-object study in your practice images: value control with no local colour to hide behind is unmistakable visual evidence of the light and shade skill.
• Photograph dark drawings carefully. Charcoal darks crush to a black mush in bad light; recheck the value range on screen before submitting.
• Keep your notan thumbnails and submit a page of them as a process image — planning evidence directly supports the Sustained Investigation rubric.