GIMP – GNU Image Manipulation Program

Complete Guide to GIMP: Professional Image Editing for Everyone

GIMP (GNU Image Manipulation Program) stands as the most powerful free and open-source image editor available, offering professional-grade features rivaling expensive commercial alternatives. From photo retouching and composition to graphic design and digital art creation, GIMP provides the tools needed for virtually any image manipulation task. Its extensibility through plugins and scripts, combined with cross-platform availability, makes it accessible to users on any operating system.

The software has evolved over decades of development, gaining sophisticated features like non-destructive editing, advanced layer management, and extensive format support. Whether you’re a photographer, designer, or casual user, GIMP adapts to your workflow while costing nothing.

Installing GIMP

# Ubuntu/Debian
sudo apt update
sudo apt install gimp

# Flatpak (latest version)
flatpak install flathub org.gimp.GIMP

# Fedora
sudo dnf install gimp

# Arch Linux
sudo pacman -S gimp

# macOS
brew install --cask gimp

# Windows
winget install GIMP.GIMP

# Verify installation
gimp --version

Interface Overview

# Default layout:

# Toolbox (left)
- Selection tools
- Paint tools
- Transform tools
- Color tools

# Image window (center)
- Canvas area
- Rulers
- Navigation

# Dockable dialogs (right)
- Layers
- Channels
- Paths
- Undo History
- Brushes
- Patterns

# Customize layout:
Windows > Dockable Dialogs
Drag tabs to rearrange
Windows > Save Window Layout

# Single-window mode:
Windows > Single-Window Mode

Basic Operations

# Create new image
File > New (Ctrl+N)
Set width, height, resolution
Choose color space (RGB, Grayscale)

# Open image
File > Open (Ctrl+O)
File > Open as Layers

# Save and export
File > Save (Ctrl+S) - XCF format (native)
File > Export As (Ctrl+Shift+E) - Other formats

# Canvas operations
Image > Canvas Size
Image > Fit Canvas to Layers
Image > Flatten Image

# Scale image
Image > Scale Image
Set new dimensions
Choose interpolation method

# Crop image
Image > Crop to Selection
Image > Autocrop Image
Use Crop Tool (Shift+C)

Selection Tools

# Rectangle Select (R)
- Hold Shift for square
- Hold Ctrl to start from center

# Ellipse Select (E)
- Hold Shift for circle

# Free Select/Lasso (F)
- Click points for polygon
- Drag for freehand

# Fuzzy Select/Magic Wand (U)
- Select by color similarity
- Adjust threshold in options

# Select by Color (Shift+O)
- Select all matching colors

# Scissors Select (I)
- Intelligent edge detection

# Foreground Select
- Select complex objects

# Selection operations:
Select > All (Ctrl+A)
Select > None (Ctrl+Shift+A)
Select > Invert (Ctrl+I)
Select > Grow/Shrink
Select > Feather
Select > By Color

# Selection modes:
Replace (default)
Add (Shift)
Subtract (Ctrl)
Intersect (Shift+Ctrl)

Layers

# Layer operations:
Layer > New Layer
Layer > Duplicate Layer
Layer > Merge Down
Image > Flatten Image

# Layer dialog:
- Eye icon: Toggle visibility
- Chain icon: Link layers
- Lock icons: Lock pixels/alpha

# Layer modes:
Normal, Multiply, Screen
Overlay, Soft Light, Hard Light
Difference, Divide
Color, Hue, Saturation, Value

# Opacity:
Adjust layer transparency
0% = invisible, 100% = opaque

# Layer masks:
Layer > Mask > Add Layer Mask
White reveals, black conceals
Paint on mask to show/hide

# Layer groups:
Layer > New Layer Group
Organize complex compositions

# Shortcuts:
Page Up/Down: Switch layers
Shift+Ctrl+E: Merge visible

Paint Tools

# Paintbrush (P)
- Soft and hard brushes
- Adjust size, opacity, flow

# Pencil (N)
- Hard-edged drawing
- No anti-aliasing

# Airbrush (A)
- Pressure-sensitive spray

# Ink (K)
- Calligraphy-style strokes

# Clone (C)
- Copy pixels from source
- Ctrl+Click to set source

# Heal (H)
- Smart clone for retouching
- Blends with surroundings

# Blur/Sharpen (Shift+U)
- Soften or enhance edges

# Smudge (S)
- Push pixels like wet paint

# Dodge/Burn (Shift+D)
- Lighten or darken areas

# Brush options:
- Size, Hardness, Aspect Ratio
- Angle, Spacing
- Dynamics (pressure sensitivity)

# Brush editor:
Windows > Dockable Dialogs > Brushes
Create custom brushes

Transform Tools

# Move (M)
- Move layers or selections
- Pick layer mode in options

# Rotate (Shift+R)
- Rotate layer or selection
- Set angle precisely

# Scale (Shift+S)
- Resize proportionally (chain icon)

# Shear (Shift+H)
- Slant horizontally or vertically

# Perspective (Shift+P)
- Adjust perspective/vanishing point

# Flip (Shift+F)
- Horizontal or vertical flip

# Unified Transform (Shift+T)
- All transforms in one tool

# Cage Transform
- Warp with control points

# Warp Transform (W)
- Push, shrink, grow pixels

# Transform options:
- Direction: Normal/Corrective
- Interpolation: None to Cubic
- Clipping: Adjust/Clip/Crop

Color Adjustments

# Colors menu:

# Levels (Ctrl+L)
- Adjust shadows, midtones, highlights
- Input/output levels

# Curves
- Precise tonal control
- Create S-curves for contrast

# Brightness-Contrast
- Simple adjustments

# Hue-Saturation
- Adjust colors by range
- Colorize images

# Color Balance
- Adjust shadows/midtones/highlights
- Add color casts

# Threshold
- Convert to black and white

# Posterize
- Reduce color levels

# Desaturate
- Convert to grayscale
- Multiple methods

# Invert
- Negative effect

# Auto adjustments:
Colors > Auto > Normalize
Colors > Auto > Stretch Contrast
Colors > Auto > Color Enhance

Filters

# Blur filters:
Filters > Blur > Gaussian Blur
Filters > Blur > Motion Blur
Filters > Blur > Lens Blur

# Enhance filters:
Filters > Enhance > Sharpen
Filters > Enhance > Unsharp Mask
Filters > Enhance > Noise Reduction

# Distort filters:
Filters > Distorts > Lens Distortion
Filters > Distorts > Spherize
Filters > Distorts > Ripple

# Artistic filters:
Filters > Artistic > Cartoon
Filters > Artistic > Oilify
Filters > Artistic > Photocopy

# Light and Shadow:
Filters > Light and Shadow > Drop Shadow
Filters > Light and Shadow > Vignette
Filters > Light and Shadow > Lens Flare

# Render filters:
Filters > Render > Clouds
Filters > Render > Pattern
Filters > Render > Fractal

# Filter preview:
Enable in filter dialog
Zoom and pan in preview

Text Tool

# Text Tool (T)
Click to start typing
Drag to create text box

# Text options:
- Font family and size
- Bold, italic, underline
- Color
- Justification
- Letter/line spacing

# Edit text:
Double-click text layer
Or use Text Tool on layer

# Text to path:
Layer > Text to Path
Allows text manipulation

# Text along path:
Create path
Text > Text along Path

# Render text:
Layer > Discard Text Information
Converts to regular layer

Paths

# Paths Tool (B)
Click to add points
Drag handles for curves

# Path operations:
- Select path in Paths dialog
- Stroke Path: Draw along path
- Path to Selection
- Selection to Path

# Bezier curves:
Ctrl+click for corner points
Drag handles for curves

# Edit paths:
Click and drag points
Shift+click to add point
Ctrl+Shift+click to delete

# Export paths:
Export as SVG
Import SVG as path

Batch Processing

# Python-Fu console:
Filters > Python-Fu > Console

# Batch resize example:
from gimpfu import *
import os

def batch_resize(folder, width, height):
    for filename in os.listdir(folder):
        if filename.endswith(('.jpg', '.png')):
            filepath = os.path.join(folder, filename)
            image = pdb.gimp_file_load(filepath, filename)
            pdb.gimp_image_scale(image, width, height)
            pdb.file_png_save(image, image.layers[0],
                filepath.replace('.jpg', '.png'), filename, 0, 9, 1, 1, 1, 1, 1)

# Script-Fu:
Filters > Script-Fu > Console

# BIMP plugin:
Install BIMP for GUI batch processing
Apply actions to multiple files

Keyboard Shortcuts

# File operations:
Ctrl+N         New image
Ctrl+O         Open
Ctrl+S         Save
Ctrl+Shift+E   Export As
Ctrl+Q         Quit

# Edit:
Ctrl+Z         Undo
Ctrl+Y         Redo
Ctrl+X         Cut
Ctrl+C         Copy
Ctrl+V         Paste

# View:
1              Fit in window
Shift+Ctrl+E   Fit image in window
+/-            Zoom in/out

# Select:
Ctrl+A         Select all
Ctrl+Shift+A   Select none
Ctrl+I         Invert selection

# Image:
Shift+Ctrl+R   Rotate 90° CW
Shift+Ctrl+D   Duplicate image

# Layers:
Ctrl+Shift+N   New layer
Ctrl+M         Merge down
Page Up/Down   Navigate layers

# Customize:
Edit > Keyboard Shortcuts

Tips and Tricks

# Quick mask (Shift+Q):
Paint selection with brush
Red area = unselected

# Color picker (Ctrl):
Hold Ctrl while painting
Pick color from canvas

# Straight lines:
Click once, hold Shift, click again

# Center guides:
Image > Guides > New Guide by Percent (50%)

# Precise positioning:
Tool Options > Position

# Reset tool options:
Tool Options menu > Reset to Default

# Zoom to selection:
View > Zoom > Fit Selection in Window

Conclusion

GIMP provides comprehensive image editing capabilities without cost, making professional-grade tools accessible to everyone. Its extensive feature set covers everything from basic photo editing to complex digital art creation. While the learning curve can be steep, mastering GIMP rewards users with powerful, flexible image manipulation capabilities that rival expensive commercial software.