Before/After Photo Editing Comparison with Image Diff

Before/After Photo Editing

Comparing images before and after editing is essential for evaluating the impact of retouching, color grading, compositing, and other post-processing operations. Image diff tools provide objective, measurable feedback beyond subjective visual assessment.

Editing Operations and Their Diff Signatures

Different editing operations produce characteristic patterns in pixel diffs:

Color Grading / LUTs

• Changes are distributed uniformly across the entire image
• Difference percentage is typically high (50-100%) because every pixel shifts
• The diff image appears as a uniform color cast rather than localized changes

Retouching / Healing

• Changes are localized to specific regions (skin, backgrounds)
• The bounding box clearly outlines the retouched area
• Surrounding unchanged areas provide context for evaluating the edit

Compositing / Object Insertion

• Sharp boundaries between changed and unchanged regions
• The diff clearly shows the outline of inserted elements
• Edge artifacts may be visible at insertion boundaries

Sharpening / Blur

• Changes concentrate along edges and high-contrast boundaries
• The diff image highlights the edge enhancement pattern
• Low-contrast areas show minimal change

Using Overlay Slider

The overlay slider mode is particularly useful for photo editing comparison:

1. Position the slider at the center to see the transition point
2. Slowly slide left and right to reveal changes progressively
3. Focus on skin tones, eyes, and backgrounds for portrait retouching
4. Check horizon lines and perspective for landscape editing

Evaluating Edit Quality

A good edit should show:

• Smooth transitions at edit boundaries (no hard edges)
• Consistent noise patterns (edited areas should not look smoother or noisier than surroundings)
• Natural color gradients (no banding or posterization introduced by editing)