Drag to compare before / after images
A draggable divider over two images, side by side. Drop a before and an after, then snapshot the result. Runs locally.
image/* · runs locally · nothing uploaded
image/* · runs locally · nothing uploaded
How it works
Pick an image, tune the options, then download the result. Everything runs in your browser.
- 01
Pick before image
Drop any image as the baseline shown on the left of the divider.
Files stay in memory as an
HTMLImageElement— the original bytes are never uploaded, and EXIF metadata is preserved until you explicitly transform it.Auploadcanvaslocaldecodeimage · bytesA · loadedload: before.png
loaded · decodedcanvas · ready - 02
Pick after image
The second image fills the right side of the divider.
Encoder quality is exposed where the format supports it — JPEG and WebP get a
0–1quality slider; PNG is lossless. Options re-render the canvas immediately.Boptionslive previewencoderqualityimage · tunableB · liveload: after.png
options applied · liveencoder · live - 03
Drag the divider
Move the slider to reveal more of the after or before image.
Pixel work runs on the Canvas 2D context —
drawImageresamples with the browser’s bilinear filter andgetImageData/putImageDataback per-pixel passes.dragrenderCanvas 2Dpreviewpx-perfectpos · resampled50% · px-perfectclip: inset(0 0 0 50%)
preview · livepx-perfect - 04
Download snapshot
Save a PNG that bakes in the current divider position with a white seam.
Downloads ship via a hidden anchor with an object URL — no server round-trip, and the file on disk is untouched. The output filename inherits a sensible suffix.
exportdownloadblobclient-sideobject URLok · blobready · savedcomparison.png
shipped · ready to shipsuccess
Browser-only image work that scales
Convert with quality control
JPEG/WebP let you pick a 0–1 quality. Default 0.92 is a good compromise of size and visible quality.
PNG isn’t free
Use PNG only for transparency or sharp edges. For photos, WebP is smaller at the same perceived quality.
Strip EXIF for privacy
Photo EXIF often contains GPS, camera model, and timestamps. Strip before sharing public uploads.
Watch the colour profile
Convert to sRGB before web export. Wide-gamut images render oversaturated in non-managed browsers.
AVIF when it’s available
AVIF beats WebP on size at the same quality. Detect support via <picture> with fallbacks.
Lazy-load below the fold
Add loading="lazy" on <img>. The browser handles scheduling — no IntersectionObserver needed.
When to use this tool
Common workflows it speeds up.
Color grading
Show graded vs ungraded shots side by side. Decoded into a Canvas 2D context — original bytes never leave the tab, so you can process customer-uploaded photos, internal screenshots, or sensitive diagrams without privacy concerns.
px-perfectRetouch diffs
Demonstrate retouching changes on portraits. Encoders expose quality 0–1 where the format supports it (JPEG, WebP); PNG and AVIF stay perceptually lossless. Pick 0.85 for web, 0.95 for archival, 0.7 for thumbnails.
quality-tunableMarketing pages
Embed a snapshot in landing pages for product demos. Pair with the EXIF Stripper before sharing user-uploaded photos publicly. Camera serial numbers, GPS coordinates, and timestamps often hide in image metadata and leak more than the picture itself.
format-awareUI refactors
Document old vs new layout to PMs and designers. Output preserves colour profile (sRGB) so it renders consistently across browsers, monitors, and print pipelines. Wide-gamut workflows can opt into Display P3 for modern Apple devices.
EXIF-safeMap updates
Show before-and-after of map renders or tiles. Re-runs only on option changes, never on window resize, so the canvas stays responsive on large images. drawImage uses the browser's bilinear filter for fast resampling.
client-sideAI/ML demos
Show input vs model output on the same canvas. Downloads as .png, .jpg, .webp, or .avif with the correct MIME so editors apply native handling on save. The filename inherits a sensible suffix derived from the input.
compression-readyFrequently asked questions
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