Colorize Grayscale Paintings in Photoshop (Overlay, Multiply, Gradient Map)
When colorizing a grayscale painting, the goal is to add rich color while protecting your hard-earned values. This method starts by slightly lowering contrast, laying in subtle global color, then layering Overlay/Multiply paint and Gradient Maps for controlled hue shifts. You’ll clip effects to parts, reuse maps, and mask in nuanced lighting and materials.
Step-by-step instructions
Prep values before colorizing
Add Layer → New Adjustment Layer → Levels.
Reduce contrast by raising Output Black toward mid-gray and lowering Output White slightly; aim for a softer overall range so later layers don’t over-contrast.
Infuse a subtle global cast
Add Layer → New Adjustment Layer → Color Balance.
Push Shadows slightly warmer (toward Red/Yellow) and Highlights slightly cooler (toward Cyan/Blue); lightly adjust Midtones to taste.
Decide layer handling for multi-part characters
Option A (manual): Clip adjustments to each relevant layer (Ctrl/Alt+G or Layer → Create Clipping Mask) and merge (Ctrl/Cmd+E) where needed.
Keep adjustments separate if you prefer flexibility—but expect more layers.
Lay in skin and hair color with Overlay
On the face layer, create a new pixel layer and set its blending mode to Overlay; clip it (Ctrl/Alt+G).
Paint base skin color with a soft brush; keep values mid-range to avoid crushing detail.
For hair, try another Overlay layer; if testing hues, adjust with Image → Adjustments → Hue/Saturation until you like it.
To sample the resulting hue, temporarily set the layer to Normal, eyedropper the color, then set back to Overlay and reuse on other hair layers.
Avoid the flat “colorized” look
Create a Multiply layer (clipped) to warm shadows with a subtle orange tone; let it creep into midtones slightly.
Create an Overlay layer to cool highlights with a gentle light blue on the lit side.
If skin goes too pale, add another Multiply pass to pull values down; keep iterating small pushes/pulls.
Unify overlapping parts
If a highlight (Overlay) spans multiple hair layers, move that highlight layer above, clip to the first hair layer, duplicate (Ctrl/Cmd+J), and clip the copy to the second hair layer for a seamless transition.
Colorize materials with Gradient Map
Add Layer → New Adjustment Layer → Gradient Map and clip it to the target element (Ctrl/Alt+G).
Edit the gradient: add nodes (e.g., a mid node ~50%) and assign colors for shadows→mids→highlights (e.g., warm shadows to neutral bone to bluish highlights).
Test blending modes (start with Color) to preserve values; adjust node positions until the material reads well.
Shape color along forms with masks
For tips/edges needing different hue/value, add Layer → New Adjustment Layer → Hue/Saturation above the Gradient Map.
Invert its mask (Ctrl/Cmd+I), then paint white where you want darker, less saturated, or shifted color (e.g., bluer/darker tips).
Differentiate materials on shared layers
If multiple materials exist on one paint layer, add clipped Overlay/Multiply layers and hand-paint distinct hues (e.g., neutral brown for belts over purple cloth) to avoid uniform coloring.
Reuse and adapt Gradient Maps
Alt-drag an existing Gradient Map to duplicate it onto similar materials (e.g., from a headdress bone to a skull), then clip it and tweak Levels beneath to align values so the map “lands” correctly.
Create patina and special effects
For oxidized bronze, stack a second Gradient Map set to Hue on top of the base metal map; invert its mask and paint greenish-blue patina with a textured brush.
For pearly beads, use a Lighten-mode layer to brush subtle greens/purples that lift shadow values; adjust layer Opacity to balance.
Global cohesion pass
Add a gentle Hue/Saturation to nudge overall saturation.
Use an Overlay paint layer to warm shadows and cool highlights slightly for harmony.
Review and fine-tune masks and opacities across elements for a cohesive finish.
