Image Compare Tool
Compare two images side by side, with a split slider, or via pixel diff to inspect compression artifacts. All rendering runs locally in your web browser.
JPG, PNG, WebP, GIF · two files · the first counts as left/before, the second as right/after
Two images are required for a comparison.
Tips
- Drag the center divider in slider mode to reveal localized compression artifacts between identical coordinates.
- Look for solid black areas in difference mode to confirm where both images match bit-for-bit.
- Uploading images with mismatched dimensions automatically resizes the smaller asset to match the larger file boundary.
How to use it
- 1 Upload your primary reference image alongside the modified or compressed version.
- 2 Select your preferred viewing layout between slider, side-by-side, or difference mode.
- 3 Drag the comparison handle or inspect highlighted pixels to locate visual variations across the canvas.
What you should know
Evaluating image fidelity after lossy compression or color profile conversions requires precise visual inspection. When re-encoding high-resolution assets to WebP, AVIF, or lower-quality JPEG formats, quantization tables and chroma subsampling introduce subtle blocking artifacts, ringing around high-contrast edges, and slight shifts in 8-bit color depth. Without direct overlay comparison, pinpointing where visual data degrades or whether text sharpness remains acceptable across different display pixel densities is difficult. Designers, web developers, and catalog managers need immediate feedback to balance bandwidth savings against perceptible visual quality before publishing graphics online.
This tool renders two selected images directly on an HTML5 canvas to provide three inspection views: a split slider, a side-by-side layout, and a pixel-by-pixel difference map. In difference mode, identical pixels display as solid black, while any variation in RGB color values or alpha transparency lights up brightly to highlight altered areas. If your source files differ in dimensions, the smaller file automatically scales to match the larger canvas area for direct alignment. Processing occurs entirely in client-side memory, preserving local privacy without transferring raw assets over the network.
Frequently asked questions
Why does the difference mode display a completely black screen?
A black screen means every RGB color channel and alpha value matches perfectly across both images at those coordinates. Any pixel with even a minor brightness or chromatic alteration will illuminate.
How does the tool handle two images with different resolutions?
The tool rescales the smaller image canvas to match the larger file dimensions so you can inspect structural alignment. For pixel-accurate diff calculations, resizing beforehand produces the most reliable output.
Are my uploaded graphics transferred to an external server?
No, all image decoding and canvas rendering happen locally inside your browser memory using Web APIs. Your files are never transmitted across the network or stored remotely.
Guides
Articles and format references related to this tool.
- Which Image Format Should I Use? Complete Guide 9 September 2026
- How to Prepare a Product CSV File: Complete Guide 9 September 2026
- 7 Common Product CSV Import Errors and How to Fix Them 31 August 2026
- What is a JPG file? Lossy (DCT)
- What is a PNG file? Lossless (Deflate)
- What is a WebP file? Both lossy and lossless
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