Retouching II

• 01
  Non-Destructive Dodge and Burn — The Soft Light Layer Method

  Create a new transparent layer above the image (Shift+Ctrl+N, fill: Transparency). Name it "dodge-burn". Fill it with 50% grey: set the foreground colour to #808080, then Edit → Fill with FG Color. Set this layer's blend mode to Soft Light. The 50% grey layer is now completely invisible — Soft Light's neutral value is 50% grey, so it contributes nothing to the image. Now activate the Paintbrush (P). To dodge (lighten): set the foreground to white (#FFFFFF), use a large soft brush at 10–15% opacity, and paint over the area to brighten. To burn (darken): set the foreground to black (#000000) at the same settings and paint over the area to darken. Press X to swap between white and black. Each pass accumulates — multiple soft strokes build up the effect gradually, giving precise local control. Because you are painting on a separate layer, the original image is never touched. Reduce the "dodge-burn" layer's opacity to scale the total effect at any time.

  New layer "dodge-burn" → fill #808080 → Mode: Soft Light → Paintbrush white (dodge) / black (burn) at 10–15% opacity
• 02
  Why Soft Light at 10–15% Opacity — Understanding Accumulation

  At 10% opacity, a single white brushstroke shifts the grey value under the brush from 128 (neutral) to approximately 138 — a very slight brightening. After ten overlapping strokes at the same position, the value reaches approximately 230 — a significant brightening approaching white. This accumulation behaviour is the reason low opacity is essential: it gives you fine-grained control over the final effect. At 100% opacity, a single stroke drives the value immediately to 255 (fully white), producing a clipped, unnatural highlight. Use 5–10% for subtle skin retouching. Use 15–20% for environmental light sculpting. Use 30% only for deliberate vignette darkening where a strong effect is intentional. Never exceed 50% opacity per stroke.

  Opacity 5–10%: subtle skin. 15–20%: light sculpting. 30%: intentional vignette. Never exceed 50% per stroke.
• 03
  GIMP's Native Dodge and Burn Tools — When to Use Them

  GIMP's native Dodge tool (Shift+D) and Burn tool (the same tool with a mode switch in Tool Options) do exist and can be useful for quick, coarse work — but they are destructive and should only ever be applied to a duplicate layer, never the original. Their key option is the Range selector, which targets the effect to a specific tonal zone:

  Shadows

  Affects dark tones most

  Dodging Shadows brightens only the dark areas of the image. Burning Shadows deepens them further. Use for opening shadow detail or deepening dark backgrounds.

  Midtones

  Affects mid-grey tones most

  The broadest range — affects the largest proportion of pixels in most photos. Use with care; midtone dodge/burn shifts the overall exposure of the affected area quickly.

  Highlights

  Affects bright tones most

  Dodging Highlights brightens already-bright areas toward white — risky, can clip detail. Burning Highlights pulls bright areas down, recovering highlight texture. Use for specular control.

  The Exposure slider in Tool Options controls intensity — keep it at 10–20% for controlled results. The native tools' key advantage over the Soft Light method: the Range selector, which confines the effect to a specific tonal zone. For this reason, native Dodge/Burn on a duplicate layer is appropriate when you need to recover shadow detail without affecting highlights, or vice versa.

• 04
  Viewing the Dodge-Burn Layer in Isolation

  To see exactly what you have painted on the Soft Light dodge-burn layer, temporarily switch its blend mode to Normal. The grey layer with your white and black brushstrokes becomes visible — white areas are dodged regions, black areas are burned regions, and the 50% grey fill shows where you have not painted. This isolation view lets you evaluate the shape and distribution of your local adjustments: are the transitions smooth? Are there any accidental strokes you want to erase? Use the Eraser on the dodge-burn layer to remove marks while in Normal mode, then switch back to Soft Light to restore the invisible baseline and evaluate the result on the image.

  Temporarily set dodge-burn layer mode to Normal → inspect grey/white/black marks → Eraser to remove mistakes → switch back to Soft Light
• 05
  Smudge Tool — Blending and Softening by Dragging

  Activate the Smudge tool (S). It drags existing pixels in the direction of the brush stroke, smearing and blending them as it goes — like dragging wet paint. The Rate slider in Tool Options controls how aggressively pixels are pulled: a low rate (20–40%) produces a subtle drag that blends without completely destroying detail; a high rate (70–100%) produces a strong smear that significantly distorts the underlying pixels. Key uses: softening harsh transitions at a mask edge (smudge the edge pixels to blend them into the new background); blending skin texture in a targeted zone more subtly than Gaussian Blur (smudge in the direction of facial contours — this preserves directional texture that isotropic blur destroys); and extending or reshaping hair strands at the edge of a subject cutout. Always work on a duplicate layer — Smudge is destructive.

  Smudge tool (S) → Rate 20–40% for subtle blending, 70–100% for aggressive smear → work on duplicate layer
• 06
  Blur Tool vs Gaussian Blur Filter — Local vs Global

  GIMP provides two distinct blur approaches. The Blur/Sharpen tool in the Toolbox (keyboard shortcut: Shift+U to cycle) paints a progressive blur with the brush — each stroke softens the pixels under it by a small amount, and repeated strokes accumulate. It is local and directional, controlled by brush size, the Rate slider, and stroke placement. Use it for targeted softening of specific small areas without affecting adjacent pixels. The Filters → Blur → Gaussian Blur filter applies a mathematically uniform blur across an entire layer (or within an active selection) at once. It is global (or selection-bounded) and isotropic (affects all directions equally). Use it for: softening a layer mask edge uniformly (Session 6), creating depth-of-field effects on a background layer, or as the first step of the Unsharp Mask sharpening technique. For retouching, the Blur tool is the better choice for targeted skin softening; Gaussian Blur is better for full-layer effects.

  Blur tool (Shift+U): local, targeted, stroke by stroke. Filters → Blur → Gaussian Blur: global, full layer or selection, single operation.
• 07
  Non-Destructive Skin Softening with Gaussian Blur + Layer Mask

  For portrait skin softening, the industry-standard technique in GIMP is: duplicate the image layer. Apply Filters → Blur → Gaussian Blur at a radius of 4–8 pixels to the duplicate — enough to smooth skin texture but not so much that features dissolve. Reduce the blurred layer's opacity to 60–80% (this restores some texture). Add a black layer mask to the blurred layer (initialise: Black / full transparency). The blurred layer is now completely hidden. Paint white on the mask with a soft brush at 80–100% opacity over the skin areas only — forehead, cheeks, chin, neck — revealing the blur selectively. Avoid eyes, eyebrows, lips, hair, clothing, and any area where sharpness matters. The result: softened skin in one fully non-destructive layer that can be refined, erased, or discarded entirely.

  Duplicate layer → Gaussian Blur 4–8px → reduce opacity 60–80% → add black mask → paint white over skin areas only
• 08
  Sharpen Tool and Unsharp Mask — Adding Local and Global Sharpness

  The Sharpen side of the Blur/Sharpen tool (cycle with Shift+U) increases local contrast under the brush — it makes edges appear crisper by increasing the tonal difference between adjacent pixels. Use it at a very low Rate (10–20%) on specific details: the iris of an eye, a product label, the edge of a crisp object. Use it on a duplicate layer; excessive sharpening produces visible white haloes around edges. For full-image or large-area sharpening, use Filters → Enhance → Unsharp Mask — confusingly named, it is a sharpening tool. The three parameters: Radius controls how many pixels each edge contrast boost spans (typically 0.5–2.0 for portraits, 1.0–3.0 for landscapes and products). Amount controls intensity (0.3–0.6 for subtle output sharpening, 0.5–1.0 for strong creative sharpening). Threshold controls the minimum tonal difference an edge must have before sharpening is applied — a higher threshold skips low-contrast areas like smooth skin and only sharpens well-defined edges. Set Threshold to 3–8 for portrait sharpening to protect skin.

  Sharpen tool (Shift+U): local detail emphasis at low Rate. Filters → Enhance → Unsharp Mask: full-layer/selection sharpening with Radius, Amount, Threshold.
• 09
  Sharpening Workflow — Output Sharpening at the End

  Sharpening is the last step of any retouching workflow, applied after all tonal corrections, colour corrections, and retouching are complete. Sharpening amplifies existing pixel differences — if applied early, subsequent corrections amplify those haloes further. Apply sharpening to a flattened duplicate of the finished image, or to a merged-visible copy (Shift+Ctrl+Alt+E on some configurations, or Layer → New from Visible in GIMP 3.2). Parameters for output sharpening differ by output medium: for web/screen (72–96 PPI): Unsharp Mask at Radius 0.5–1.0, Amount 0.4–0.6, Threshold 3–5. For print (300 PPI): Radius 1.0–2.0, Amount 0.5–0.8, Threshold 4–8. For large print (150 PPI): Radius 2.0–3.0, Amount 0.3–0.5, Threshold 5–10. Always evaluate sharpening at 100% zoom — at 50% the effect looks invisible; at 200% it looks over-sharpened. The correct view is 100%.

  Sharpen last. Merge visible to new layer. Unsharp Mask: web (R:0.5–1, A:0.4–0.6, T:3–5) · print (R:1–2, A:0.5–0.8, T:4–8)
• 10
  Finishing Workflow — Vignette and Micro-Contrast

  Two final finishing touches that appear in most professional retouching workflows. Vignette: on the dodge-burn Soft Light layer, use a large soft black brush at 15–20% opacity and paint the corners and edges of the image — the outer portions darken gently, drawing the eye toward the centre. This is the most common single finishing step in portrait photography. Evaluate by toggling the layer — a good vignette should be noticed when removed, not noticed when present. Micro-contrast (local contrast enhancement): duplicate the flattened image. Apply Filters → Blur → Gaussian Blur at a very large radius (40–80px) — this creates a blurred "illumination map" of the image. Set this blurred layer to Overlay blend mode at 10–20% opacity and invert it (Colors → Invert). The result: a subtle boost to local edge contrast across the entire image that increases perceived three-dimensionality and texture richness. This technique is the manual equivalent of the "clarity" slider in other software.

  Vignette: soft black brush at corners on Soft Light layer. Micro-contrast: duplicate → Gaussian Blur large radius → Invert → Overlay mode 10–20%

Open a portrait photograph. You will apply a complete finishing pass — skin softening, dodge and burn sculpting, selective sharpening, and a finishing vignette — using only the non-destructive techniques from this session.

• A
  Skin softening with Gaussian Blur + black mask

  Duplicate the base layer. Apply Filters → Blur → Gaussian Blur at 5px. Reduce opacity to 70%. Add a black mask (Layer → Mask → Add Layer Mask → Black). Paint white on the mask with a soft brush at 90% opacity over the skin: forehead, cheeks, nose bridge, chin, neck. Do not paint over eyes, lips, eyebrows, hair, clothing, or background. Check the mask in isolation (Alt+click mask thumbnail) — only skin areas should be white.

• B
  Dodge and burn the face with the Soft Light layer

  Above all current layers, create the dodge-burn layer: new transparent layer, fill #808080, mode Soft Light. Using a large soft brush (roughly the size of a cheekbone) at 10% opacity, paint white on the highlights — the forehead, the top of the nose, the upper cheekbones, the chin point. These are the areas that would catch the most light from above. Switch to black and darken the shadows — under the cheekbones, under the jaw, the sides of the nose. Make multiple passes at low opacity rather than one heavy pass. Switch the layer temporarily to Normal mode to inspect your strokes, then back to Soft Light to see the result.

• C
  Selective sharpening of the eyes and lips

  Create a merged-visible copy: hold Shift+Ctrl and click Layer → New from Visible (or use Edit → Copy Visible, then paste as a new layer). Name it "sharpen". Activate the Sharpen tool (Shift+U to cycle). Set Rate to 15%. Zoom to 200%. Paint carefully over the eyelashes, iris, and eyebrows — two or three passes. Paint over the lip edges. Do not sharpen the skin. Zoom to 100% and evaluate: the eyes should appear noticeably crisper; the skin should look unchanged.

• D
  Add a finishing vignette

  On the dodge-burn Soft Light layer, switch to a very large soft brush (500px or more — as large as possible while staying within the canvas). Set foreground to black, opacity 20%. Paint once over each corner. Paint once along each edge with a partial stroke. Check the result: toggle the dodge-burn layer visibility. The vignette should be felt as a drawing inward of the eye rather than seen as an obvious darkening of the corners. Reduce the layer opacity if the effect is too strong.

Open a landscape photograph. Apply the micro-contrast technique from Step 10, then refine with targeted dodge-and-burn to direct the viewer's eye to the compositional centre of interest. No step-by-step guidance.

• →
  Apply micro-contrast enhancement

  Flatten a working copy of your image to a new layer (Layer → New from Visible). Apply Filters → Blur → Gaussian Blur at radius 60px. Set the layer blend mode to Overlay. Apply Colors → Invert to the blurred layer. Reduce opacity to 15–20%. Toggle the layer visibility — the landscape should look more three-dimensional and textured with the layer on. If the effect looks overdone, reduce opacity further. If it looks muddy rather than three-dimensional, the blur radius may be too small — try 80–100px.

• →
  Guide the eye with dodge and burn

  Create a Soft Light dodge-burn layer. Identify the compositional centre of interest in your landscape — a mountain peak, a building, a lone tree, a breaking wave. Paint white over it at 10% opacity (3–4 passes) to lift it slightly from its surroundings. Paint black over the less important areas — the edges, the flat foreground, areas that compete with the centre of interest. The goal: the viewer's eye should be drawn immediately to the brightened centre when viewing the image at 100% zoom. Compare this result with the unvignetted version — the eye movement should be measurably different.