Image Comparison Slider

A before/after image comparison slider overlays two images and lets you drag a divider to reveal one over the other. It is the fastest way to visually inspect differences between two versions of a photo — before and after retouching, color grading, noise reduction, sharpening, compression, or AI upscaling. Unlike side-by-side viewing, the slider aligns both images pixel-for-pixel so even subtle changes are immediately visible. This free online photo comparison tool supports JPEG, PNG, WebP, AVIF, BMP, and TIFF. For pixel-level numerical difference maps, use the Image Similarity Scanner. To check whether edits introduced compression artifacts, try the Image Quality Analyzer.

Both images zoom and pan in perfect lockstep — scroll the mouse wheel to magnify up to 5x, then drag to navigate when zoomed in. This synchronized zoom ensures you are always comparing the exact same pixel region in both images, critical for evaluating sharpening halos, chroma noise reduction, lens correction, detail preservation after JPEG recompression, or AI enhancement artifacts. Touch-screen devices can pinch-to-zoom and drag natively. For a detailed per-channel histogram comparison between two images, use the Image Histogram. To inspect EXIF metadata differences (e.g., different software versions), try the EXIF Checker.

Click Download Comparison to save the current slider view as a single full-resolution PNG — the divider line, labels, and split position are baked into the output image. This is ideal for portfolio presentations, client approval workflows, blog posts demonstrating editing techniques, or social media posts showcasing retouching results. Customize the labels to say anything — "Original" / "Edited", "RAW" / "Processed", "v1.0" / "v2.0". To add a watermark or branding to the comparison image, use the Image Watermark tool. For assembling multiple comparisons into a grid, try the Collage Maker.

Photo editors compare RAW vs processed, before and after color grading, or Lightroom presets. Forensic analysts compare original vs potentially manipulated images — pair this with the ELA Scanner tool for error-level forensics. Developers compare design mockups vs implementation screenshots, or before and after image compression at different quality levels. Real estate and renovation professionals showcase before/after transformations. For checking color shifts between versions, the Color Space Viewer shows gamut differences. Explore all 88 image tools at Scanly's full toolkit.