Distinguish an alpha-capable container from an image that actually contains non-opaque pixels. The checker decodes every complete frame, scans each alpha channel value, and reports transparent share, translucent pixels, and affected frame count.
How to use WebP Transparency Checker
- Choose still or animated WebP files whose visible or hidden transparency matters to the destination workflow.
- Start the local scan so every decoded frame is checked for alpha values below fully opaque 255.
- Review actual alpha pixels against the container declaration and download the JSON report when documenting unexpected backgrounds or halos.
What this tool is good at
When to use WebP Transparency Checker
Make a precise transparency decision
Determine whether decoded still or animated content actually contains alpha below 255, including partial translucency. The result is based on the selected file's actual bytes or decoded frames, so it can support a concrete publishing or engineering decision instead of a filename-based assumption.
Troubleshoot a private production asset
Use the browser-local workflow for client images, unreleased campaigns, product media, or internal fixtures when sending the source to a generic third-party utility would create unnecessary exposure.
Document repeatable asset checks
Keep the generated output or JSON report with a ticket, content review, or migration record. Use both the actual pixel count and container declaration to diagnose halos, opaque exports, or alpha-capable files with no transparent pixels. This makes the finding reproducible for another editor or developer.
How to choose the right settings
Start from the intended destination
Use both the actual pixel count and container declaration to diagnose halos, opaque exports, or alpha-capable files with no transparent pixels. Choose settings or interpret results in the context of the actual CMS, browser, editor, size budget, animation player, or privacy policy that will consume the WebP.
Separate container facts from visual judgment
RIFF chunks, dimensions, alpha values, and encoded bytes answer technical questions, while perceived sharpness, acceptable motion, and brand appearance still require a human preview at the real display size.
Retain the authoritative original
Large animations are bounded by frame and decoded-pixel limits, and a checkerboard painted into pixels is correctly treated as opaque imagery. Keep the source until the derivative or report has been reviewed, downloaded, and tested in the destination workflow.
Practical workflow and output details
ImageDecoder produces every complete frame and a local RGBA scan counts transparent, translucent, and opaque pixels. File bytes remain in the current browser tab; only static application code or codec assets are fetched, and no image-processing request is sent to PicConverters.
Large animations are bounded by frame and decoded-pixel limits, and a checkerboard painted into pixels is correctly treated as opaque imagery. The tool reports or changes only the scope named on the page and avoids implying broader repair, anonymity, visual quality, or cross-application compatibility than the operation can establish.
Format behavior and limitations
A container can declare alpha while every decoded pixel is opaque; this tool reports both facts rather than treating the feature flag as proof of visible transparency.
Pixel scanning can use significant memory for large animations, so the shared frame and decoded-megapixel safety limits apply.
Frequently asked questions
What is the difference between transparent and translucent?
A transparent pixel has alpha below 255; a translucent pixel is partially visible with alpha between 1 and 254. The report counts both and identifies partial alpha separately.
Does a checkerboard background prove transparency?
No. A checkerboard can be painted into ordinary pixels. This tool reads decoded alpha values instead of judging appearance.
Are all animation frames scanned?
Yes. Complete decoded frames are checked up to the shared 120-frame and 40 megapixel-frame safety limits.
Related WebP tools
WebP File Analyzer
Create a detailed local report covering WebP encoding, dimensions, chunks, payload bytes, overhead, animation, alpha, and metadata.
WebP to PNG
Turn static WebP images into lossless PNG files while preserving transparent pixels.
Remove WebP Background
Remove a flat, corner-matched background from static WebP images with tolerance and feather controls.