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Photo Editing in GIMP

Master color correction, exposure fixing, background removal, and professional retouching in GIMP 3.2.4.

Intermediate ~50 min read Updated May 2026
8
Core techniques covered
Free
No paid plugins needed
Non-destruct.
All techniques preserve original

Colour Correction

Colour correction is the process of adjusting an image so that its colours appear natural and consistent. GIMP provides several tools for this - The most powerful being Curves and Levels.

Using Curves (Colors → Curves)

The Curves dialog is the most powerful colour tool in GIMP. It allows you to map input tones to output tones across the entire tonal range.

S-Curve (contrast boost)
Shadows Midtones

S-Curve: Pull the highlights up and shadows down to add contrast and punch.

Colour channels: Switch to Red, Green, or Blue channel to fix colour casts.

White point: Drag the top-right point left to brighten the entire image.

Black point: Drag the bottom-left point right to deepen shadows.

Using Levels (Colors → Levels)

Levels is simpler than Curves - It adjusts the black point, white point, and midtone gamma of an image or individual channel.

Pro tip: Use the eyedropper icons in the Levels dialog to set the black and white points automatically. Click the black dropper on the darkest point in your image, and the white dropper on the brightest white - GIMP will adjust the range to fill the full tonal spectrum.

Hue-Saturation (Colors → Hue-Saturation)

Slider What it does Typical adjustment
Hue Rotates all colours around the colour wheel ±10–15° for mood shifts
Saturation Intensifies or mutes colours +10 to +30 for vibrancy; -100 for greyscale
Lightness Brightens or darkens the whole image Use sparingly - Curves is more precise

Colour Correction Tool Comparison

Fixing Exposure Problems

Overexposed (too bright) and underexposed (too dark) photos are common issues. GIMP provides multiple ways to fix them.

Underexposed (too dark)

  1. Colors → Levels - Drag the white point left
  2. Colors → Curves - Raise the midtone point
  3. Colors → Exposure - Increase Exposure value
  4. Filters → Enhance → Unsharp Mask - Recovers detail

Overexposed (too bright)

  1. Colors → Levels - Drag the black point right
  2. Colors → Curves - Pull the highlights down
  3. Duplicate layer, set blend mode to Multiply
  4. Reduce the duplicate layer's opacity for fine control
The Multiply trick: Duplicate your layer and set its blend mode to Multiply. This darkens the entire image by exactly one stop. Reduce opacity (e.g. 50%) for a half-stop correction. Stack multiple duplicates for more darkening. Works in reverse with Screen mode for brightening.

Background Removal

Removing backgrounds is one of the most common photo editing tasks. GIMP offers several methods, each suited to different image types - For a dedicated walkthrough see our background removal guide.

Fuzzy Select (Magic Wand) Best for: solid, uniform backgrounds
  1. Click the background with the Fuzzy Select tool (U)
  2. Adjust Threshold (in Tool Options) until the whole background is selected
  3. Select → Grow by 1–2px to catch edge fringing
  4. Edit → Clear - Deletes the selection to transparency
  5. Zoom in and clean up any remaining fringing with the Eraser
Select by Color Best for: backgrounds with one dominant colour
  1. Select by Color tool (Shift+O)
  2. Click the background colour
  3. Adjust Threshold to expand the selection
  4. Invert selection (Ctrl+I) to protect subject, delete background
Foreground Select Tool Best for: complex backgrounds, hair, fur
  1. Select → By Color to rough out the subject
  2. Use Foreground Select tool for fine detail
  3. Paint roughly over the foreground (subject)
  4. GIMP computes a precise mask automatically
  5. Convert to layer mask for non-destructive result
Scissors / Paths Tool Best for: clean geometric edges (products, logos)
  1. Use the Paths tool (B) to click around the subject edge
  2. Click and drag to create curves at bends
  3. Close the path and convert to selection: Select → From Path
  4. Invert the selection and delete the background

Portrait Retouching

Professional portrait retouching in GIMP covers skin smoothing, blemish removal, eye enhancement, and teeth whitening.

Blemish & Spot Removal

  1. Duplicate the background layer (Shift+Ctrl+D) - Work on the copy
  2. Select the Heal tool (H)
  3. Hold Ctrl and click a clean skin area near the blemish to sample it
  4. Click or paint over the blemish to replace it with sampled skin
  5. Adjust brush size so it just covers the blemish

Skin Smoothing (Gaussian Blur Method)

  1. Duplicate the layer twice (you'll have Layer, Layer copy, Layer copy #2)
  2. On the top copy: Filters → Blur → Gaussian Blur (radius 10–15px)
  3. Set that layer's blend mode to Grain Extract
  4. Flatten only those two layers: Layer → Merge Down
  5. Set the merged layer's blend mode to Grain Merge
  6. Add a black layer mask - Paint white only over the skin areas to reveal smoothing

Teeth Whitening

  1. Use Select by Colour to select the teeth area
  2. Feather the selection (Select → Feather, 2–3px)
  3. Colors → Hue-Saturation - Reduce Yellow saturation, increase Lightness slightly
  4. Colors → Curves - Raise the midtones of the Blue channel slightly to counter yellowing
Retouching Task Primary GIMP Tool Difficulty
Blemish removal Heal Tool (H) Easy
Skin smoothing Gaussian Blur + Grain Merge Intermediate
Eye brightening Dodge Tool on Iris Easy
Teeth whitening Hue-Saturation + Curves Easy
Frequency separation Gaussian Blur + custom layer setup Advanced
Liquify/warp Filters → Distorts → iWarp Intermediate
Background blur Select subject → Gaussian blur background Intermediate

Crop & Straighten Photos

A straight horizon and good composition are the foundation of professional-looking photos.

Straightening a Tilted Horizon

  1. Open the Measure tool (Shift+M)
  2. Click and drag along the horizon line - GIMP shows the angle in the status bar
  3. Go to Image → Transform → Rotate by Angle - GIMP pre-fills the correction angle
  4. Click Rotate, then crop off the rotated edges using the Crop tool

Common Crop Ratios

1:1
Instagram / Avatar
16:9
YouTube / Wallpaper
4:3
Classic photo
3:2
DSLR standard

Sharpening

Sharpening enhances edge contrast to make images appear crisper. Always sharpen as a final step, after all other adjustments.

Sharpening Methods Compared

Unsharp Mask (Recommended)

Filters → Enhance → Unsharp Mask

  • Amount: How strong (0.3–0.7 for photos)
  • Radius: Edge width (0.5–2.0px)
  • Threshold: Minimum contrast to sharpen (2–5)

High-Pass Sharpening

More control, popular with professionals

  1. Duplicate layer
  2. Filters → Blur → Gaussian Blur (3–5px)
  3. Use Script-Fu to create high-pass: subtract blur from original
  4. Set blend mode to Hard Light or Overlay

Noise Reduction

High-ISO photos often contain grain or colour noise. GIMP has built-in tools to reduce it.

Method Path in GIMP Best For
Median Cut Filters → Enhance → Median Cut Heavy grain reduction
Despeckle Filters → Enhance → Despeckle Salt-and-pepper noise
Gaussian Blur (light) Filters → Blur → Gaussian Blur Subtle smoothing, then resharpen
G'MIC Denoise G'MIC plugin required Best quality noise reduction available for GIMP

Complete Photo Editing Workflow

Here is the recommended order of operations for photo editing in GIMP - Doing steps out of order can degrade quality.

  1. 1
    Backup: Duplicate the original layer immediately and keep it locked at the bottom
  2. 2
    Crop & Straighten: Fix composition and horizon before any colour work
  3. 3
    Exposure: Fix overall brightness with Levels or Curves
  4. 4
    White Balance: Remove colour casts using Curves on individual RGB channels
  5. 5
    Colour Grading: Hue-Saturation and Colour Balance for mood and vibrancy
  6. 6
    Local Adjustments: Dodge, Burn, or masked Curves for specific areas
  7. 7
    Retouching: Heal blemishes, remove distractions, fix skin
  8. 8
    Noise Reduction: Apply only if needed; before sharpening
  9. 9
    Sharpening: Always last - Unsharp Mask at the intended output size
  10. 10
    Export: File → Export As to PNG/JPG/WebP at the correct resolution

Photo Editing Capabilities: GIMP vs Alternatives

Scores are illustrative ratings (0–10) across key photo editing dimensions.

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