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 Corner Luminance Report
Compare visible decoded luminance in four fixed corner tiles sized to twenty percent of each canvas dimension.
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 Corner Luminance Report settings
This analysis uses one documented method so repeated runs on the same decoded pixels remain comparable.
Prepare the corner-luminance JSON reportThe source is not overwritten. Analysis produces a separate corner-luminance 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 corner luminance report with an inspectable review path
Each corner uses a tile whose width and height are the ceiling of twenty percent of the canvas; visible decoded luminance produces a count and mean. Compare the result with the untouched source before using it downstream.Social-ready choices
Screen same-size captures for broad corner-brightness differences before inspecting lens, lighting, crop, and subject causes separately.
What you receive
Review and download a separate corner-luminance JSON report; the original file on your device remains unchanged.
Decision guide
What image corner luminance report measures or changes
Each corner uses a tile whose width and height are the ceiling of twenty percent of the canvas; visible decoded luminance produces a count and mean.
Corner means do not diagnose vignetting, lens shading, exposure, uniform illumination, corner sharpness, or a required edit. Browser-local processing avoids a Nirmion file upload, but it cannot remove copies stored elsewhere.
MDN Canvas pixel manipulationUseful checks for image corner luminance report
- Screen same-size captures for broad corner-brightness differences before inspecting lens, lighting, crop, and subject causes 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 Corner Luminance 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 Corner Luminance Report work?
Each corner uses a tile whose width and height are the ceiling of twenty percent of the canvas; visible decoded luminance produces a count and mean. Fully transparent samples are excluded from numerical reports, while visual effects preserve source alpha. 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 Corner Luminance Report?
Corner means do not diagnose vignetting, lens shading, exposure, uniform illumination, corner sharpness, or a required edit. 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.