What you need
Choose one authorised JPEG, PNG, or WebP still image up to 20 MB and 12 million decoded pixels. Animated frames are not processed.
Image Tools / Local studio
Image Alpha Centroid Report
Locate the opacity-weighted center of decoded alpha and report pixel and normalized coordinates without considering RGB brightness.
Runs locallyNo image upload to Nirmion
Step 1 / Source
Choose one image
Drop your image here
Or browse for a JPEG, PNG, or WebP image that you own or are authorised to edit.
One file · up to 20 MB · maximum 50 megapixelsStep 2 / Output
Image Alpha Centroid Report settings
This analysis uses one documented method so repeated runs on the same decoded pixels remain comparable.
Prepare the alpha-centroid JSON reportThe source is not overwritten. Analysis produces a separate alpha-centroid JSON report.
Keep this page open until the download begins.01No server upload
The selected image is decoded and re-encoded inside this browser tab.
02Working copy released
After download, the preview URL, decoded bitmap, canvas, and selected source reference are cleared.
03Your download remains
Nirmion cannot remove the finished file from your device or browser download history.
Workflow guide
Use image alpha centroid report with an inspectable review path
Each nonzero-alpha pixel coordinate is weighted by alpha divided by 255; weighted sums yield canvas and zero-to-one centroid coordinates. Compare the result with the untouched source before using it downstream.Social-ready choices
Compare transparent icon exports for shifted opacity mass while reviewing optical alignment and visible subject shape separately.
What you receive
Review and download a separate alpha-centroid JSON report; the original file on your device remains unchanged.
Decision guide
What image alpha centroid report measures or changes
Each nonzero-alpha pixel coordinate is weighted by alpha divided by 255; weighted sums yield canvas and zero-to-one centroid coordinates.
An alpha centroid is not a luminance centroid, subject center, optical center, saliency estimate, bounding box, or alignment recommendation. Browser-local processing avoids a Nirmion file upload, but it cannot remove copies stored elsewhere.
MDN Canvas pixel manipulationUseful checks for image alpha centroid report
- Compare transparent icon exports for shifted opacity mass while reviewing optical alignment and visible subject shape separately.
- Create a bounded review result while retaining the original for comparison, correction, or a different method.
- Test representative flat areas, gradients, edges, text, transparency, and high-frequency texture before accepting the output.
Good to know
Important image boundaries
- Why might a PNG not become smaller?
- PNG is lossless and browsers do not expose a quality control for it. Choose WebP or JPEG when reducing file size matters more than exact lossless pixels.
- Are animated images supported?
- No. The workspace accepts still JPEG, PNG, and WebP files. Re-encoding an animated source would otherwise keep only one frame.
- What does clearing the file mean?
- Because processing is local, there is no Nirmion server copy to delete. The tab releases its working references after success; your downloaded output remains on your device.
Questions answered
Frequently asked questions
Does Image Alpha Centroid Report upload my image?
No. Supported JPEG, PNG, and WebP decoding, pixel inspection, transformation, and export run in your current browser tab. Nirmion does not send the selected image to its API for this workflow. The result is a separate derivative or JSON report, while the original file on your device remains unchanged and should be retained for comparison.
How does Image Alpha Centroid Report work?
Each nonzero-alpha pixel coordinate is weighted by alpha divided by 255; weighted sums yield canvas and zero-to-one centroid coordinates. Every decoded pixel contributes its alpha weight; fully transparent pixels add zero weight and RGB values are ignored. The method does not infer subjects, restore missing detail, calibrate a display, or develop raw camera data. Compare edges, gradients, text, texture, and transparent areas with the original before relying on the result.
What are the limits of Image Alpha Centroid Report?
An alpha centroid is not a luminance centroid, subject center, optical center, saliency estimate, bounding box, or alignment recommendation. The workspace accepts one supported still image up to 20 MB and caps this pixel-intensive operation at 12 million decoded pixels for predictable browser memory use. Results depend on browser decoding and encoding support. Animation, raw development, ICC calibration, layer editing, and batch processing are outside this tool's verified scope.