Retouching I

• 01
  Non-Destructive Retouching Setup — Always Use a New Layer

  Before using either tool, establish a non-destructive workflow. Create a new transparent layer above the image layer (Shift+Ctrl+N, fill: Transparency) and name it "retouch". Both Clone and Heal can paint onto this empty layer while sampling from the image below, provided you enable the correct options. This means all retouching marks live on a separate layer — they can be erased, painted over, or discarded entirely without ever altering the original photograph. It also allows reducing the opacity of the retouch layer to control the intensity of the correction non-destructively.

  New transparent layer "retouch" above image → work on this layer with Sample Merged and Sample Combined enabled
• 02
  Clone Tool — Setting the Source Point

  Activate the Clone Tool (C). In Tool Options, enable Sample Merged — this allows the tool to sample from all visible layers, not just the active "retouch" layer. Painting will happen on the active "retouch" layer while sampling from the original image below. To set the source point: hold Ctrl and click on the area you want to copy from. A crosshair cursor confirms the source is set. Move the cursor to the destination area and begin painting. As you paint, the source crosshair moves in parallel with your brush — the distance and direction between the source and destination remain constant throughout the stroke. Plan your source point to maintain this relationship across the entire area you need to cover.

  Clone Tool (C) → Tool Options: Sample Merged ON → Ctrl+click to set source → paint at destination
• 03
  Clone Tool — Brush Size, Hardness, and Alignment

  Brush size should roughly match the size of the area you are covering — a brush too large picks up context from the wrong area, a brush too small requires too many strokes and produces visible repetition patterns. Use a hard brush (hardness 80–100%) for edges and boundaries where precision matters. Use a soft brush (hardness 0–30%) for interior areas where a feathered edge helps blend the patch. The Alignment setting in Tool Options controls the source offset behaviour. "Fixed" keeps the source at the absolute position you set (Ctrl+clicked). "Aligned" (recommended) moves the source offset relative to each new stroke's start position — prevents the source from drifting to an unexpected area after you lift the brush. "Registered" aligns the source to the exact same canvas coordinates as the destination (useful for layer-to-layer cloning).

  Tool Options → brush size ≈ target area size; Alignment: Aligned (recommended); Hardness: 80–100% for edges, 0–30% for interiors
• 04
  Clone Tool — Avoiding Repetition Artefacts

  The most common clone failure is visible repetition — a distinctive texture, pattern, or shape that appears twice in the image because you sampled from an area that contained it. To avoid this: vary your source point frequently (Ctrl+click a new source position every few strokes), avoid sampling directly adjacent to the destination (the offset keeps the same relative position, so nearby sources risk walking the same features back in), and zoom in to 200% to spot repetition before it becomes too visible. If the source area has strong directional texture (wood grain, fabric weave), align the clone stroke direction with the texture direction rather than painting arbitrarily.

  Re-set source (Ctrl+click) every few strokes → vary source position → zoom in to 200% to check for repetition
• 05
  Heal Tool — Operation and Key Differences

  Activate the Heal Tool (H). The workflow is identical to Clone: enable Sample Merged in Tool Options, Ctrl+click to set a source, paint at the destination. The visual difference becomes apparent immediately — the Heal Tool's result matches the tone and colour of the destination area far better than Clone. Choose a source point from an area with similar texture to what you want, but the source's tone and colour matter less — the heal algorithm blends them away. The Heal Tool is slower to process than Clone (a brief lag after each stroke while GIMP calculates the blend) — this is normal. For small spots and blemishes, a single click rather than a dragged stroke is usually sufficient. For a single-click fix, Ctrl+click source, then single-click the blemish — the Heal calculates and the blemish disappears.

  Heal Tool (H) → Sample Merged ON → Ctrl+click source (texture match priority) → single-click or short stroke at blemish
• 06
  Heal Tool — Source Distance and Edge Avoidance

  The Heal Tool blends outward from the destination into its immediate neighbourhood to calculate the tone match. This means: if your destination is near a hard edge (the junction between a white wall and a dark shadow), the blend calculation reaches across the edge and pulls colour from both sides, producing a smeared or tinted result. Fix this by keeping the source point far enough from any edge that the blend zone doesn't cross it, or by switching to the Clone Tool for areas within 15–20 pixels of a hard edge. When healing near an edge, make smaller strokes that don't overlap the edge — stop the stroke 5–10 pixels before the boundary and heal up to the line rather than across it.

  Near hard edges: use Clone Tool instead. When healing close to an edge, stop strokes 5–10px before the boundary.
• 07
  The Retouch Workflow for Removing a Large Object

  Removing a large object (a sign, a person in the background, a parked car) requires a structured approach rather than random cloning. Work in passes: Pass 1 — rough fill: use the Clone Tool at a large brush size (matching the object's width) to fill the area with approximate background texture. Don't worry about perfection — get the general colour and texture in place. Pass 2 — structural alignment: align Clone strokes with the dominant structural lines (perspective lines on a floor, horizontal lines in a sky, vertical lines on a wall). Continuity of line direction is what makes large retouches look convincing. Pass 3 — refinement: switch to the Heal Tool at a small brush size to blend any seams, tonal mismatches, or obvious repeat patterns left by the clone passes. Zoom in to 200% for this pass.

  Pass 1: Clone (large brush) → rough fill. Pass 2: Clone (structural alignment). Pass 3: Heal (small brush) → refine seams.
• 08
  Using a Selection to Constrain Retouching

  When retouching near an important edge — the horizon line, a person's outline, a product boundary — use a selection to prevent Clone or Heal strokes from accidentally painting over the protected area. Make a selection that includes the area to be retouched but excludes the protected adjacent area. While the selection is active, Clone and Heal strokes are constrained to the selected region — the brush can overshoot the edge and nothing is painted outside the selection. This eliminates the need for tiny, timid brushstrokes near boundaries, and allows confident, full-sized strokes that do not damage the protected edge. Feather the selection by 1–2 pixels to prevent a hard visible constraint line at the selection boundary.

  Selection tools (S4/S5) → select retouch area → feather 1–2px → Clone/Heal within — strokes are constrained to selection
• 09
  Perspective Clone — Retouching on Angled Surfaces

  Activate Perspective Clone from the Toolbox (or Filters → Enhance → Unsharp Mask — note: it is in the Toolbox under the Clone group, not the Filters menu). The tool operates in two modes. Mode 1 — Modify Perspective: drag the four corner handles of the perspective grid to match the receding angle of the surface you are working on (a tiled floor, a brick wall receding into the distance, a table at an angle). The grid handles define the vanishing-point geometry. Mode 2 — Perspective Clone: switch to this mode, Ctrl+click the source point, and paint as normal. The clone copies are automatically transformed by the perspective grid as you paint — texture sampled from one area is stretched or compressed to match the perspective of the destination area. This makes it possible to clone across a receding surface without the copied texture appearing at the wrong scale.

  Toolbox → Perspective Clone → Mode: Modify Perspective → drag corners to match surface angle → Mode: Perspective Clone → Ctrl+click source → paint
• 10
  Inspecting and Evaluating Retouching Quality

  A retouching job that looks correct at your working zoom may have visible problems at 100% view. Evaluate every retouch at three zoom levels: 200% for detecting edge precision and individual brush marks. 100% for assessing whether the fix blends at the viewing resolution most people see the image at. 50% or Fit to Window for the overall impression — repetition artefacts and tonal mismatches that are subtle at 100% often become immediately obvious when slightly zoomed out. Additionally, blur your eyes or squint at the retouched area — this mimics how variations in tonal distribution are perceived when fine texture detail is removed. A tonal mismatch (a patch that is lighter or darker than its surroundings) will stand out clearly under squinting even when individual pixels look correct.

  Evaluate at: 200% (edge precision) → 100% (blend quality) → 50% (overall impression + repetition detection)

Find a photograph (or use three different ones) containing: (A) a small spot or blemish on skin or a uniform surface, (B) a background distraction (a bin, a sign, a parked vehicle), and (C) a thin line or wire crossing a plain area. You will remove each using the correct tool and approach.

• A
  Remove a skin blemish with the Heal Tool

  Set up your retouch layer. Zoom to 200%. Activate the Heal Tool (H). Set brush size slightly larger than the blemish (the brush should cover the entire mark in a single click). Ctrl+click a clear area of skin nearby with similar texture — avoid any pores, wrinkles, or other marks in the source area. Single-click the blemish. Evaluate the result. If a faint tonal ghost remains, Ctrl+click a new source and single-click again. Multiple light passes produce a cleaner result than one heavy pass.

• B
  Remove a background object with the three-pass Clone workflow

  Activate the Clone Tool (C). Select the background object's area with Free Select or Rectangle Select (feather 1–2px) to constrain your strokes. Pass 1: large brush, rough fill from a source on the same background. Pass 2: align strokes with the background's structural lines. Pass 3: small Heal brush to blend the seams. Deselect. Zoom to 100% and evaluate. Any repetition pattern? Re-set source (Ctrl+click) and clone over it.

• C
  Remove a wire or thin line

  A wire crossing a plain sky or background is a common retouching task. Activate the Heal Tool. Set a very small brush — slightly wider than the wire. Ctrl+click a source directly above or below the wire (not adjacent, which would sample the wire itself). Paint along the wire in short overlapping strokes, re-setting the source frequently to avoid creating a visible track. On a gradient sky, sample from the same vertical position as each stroke to match the sky's colour gradient at that point.

• D
  Final evaluation — toggle the retouch layer

  Toggle the "retouch" layer's visibility to compare the before and after state. Reduce the retouch layer to 80% opacity — does the correction look more or less convincing? (Sometimes slight transparency improves the blend on skin.) Zoom to 50% and evaluate for any tonal mismatches or repetition artefacts that weren't visible at 200%.

Find or photograph a tiled floor, paved path, brick wall in perspective, or any surface with a clear receding pattern. Place a small object on it (or find a photo with one). Remove the object using Perspective Clone. No step-by-step guidance.

• →
  Set the perspective grid and clone the surface

  Activate Perspective Clone. In Modify Perspective mode, drag the four corner handles to align with the receding lines of the surface — two handles should follow one set of perspective lines (e.g. the horizontal tile joints receding to the left vanishing point), two should follow the other set. Switch to Perspective Clone mode, set your source on a clean part of the surface, and paint over the object. The cloned texture should scale with the perspective as you paint across the surface. Zoom in to 100% and check whether the tile joints or surface lines continue correctly through the retouched area.

• →
  Identify where perspective clone differs from standard clone

  After completing the Perspective Clone retouch, undo it and try the same removal with the standard Clone Tool. Compare the two results at 100% zoom. The standard clone should show the surface texture at incorrect perspective scale, particularly visible if the pattern has a strong repeating element (tiles, bricks, planks). Note at what distance from the source the standard clone starts to show visible perspective errors — this tells you when Perspective Clone is necessary and when standard clone is sufficient.