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 Lightness Distribution Report
Summarize decoded HSL lightness with mean, extrema, median, and interpolated quartiles across visible pixels.
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 Lightness Distribution Report settings
This analysis uses one documented method so repeated runs on the same decoded pixels remain comparable.
Prepare the lightness-distribution JSON reportThe source is not overwritten. Analysis produces a separate lightness-distribution 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 lightness distribution report with an inspectable review path
Each visible RGB tuple becomes HSL lightness from channel maximum and minimum; sorted values provide linear-interpolated quartiles and a mean. Compare the result with the untouched source before using it downstream.Social-ready choices
Compare lightness balance across consistently prepared assets while using the luminance histogram for a different weighted brightness model.
What you receive
Review and download a separate lightness-distribution JSON report; the original file on your device remains unchanged.
Decision guide
What image lightness distribution report measures or changes
Each visible RGB tuple becomes HSL lightness from channel maximum and minimum; sorted values provide linear-interpolated quartiles and a mean.
HSL lightness is not Rec. 709 luminance, exposure, HDR range, print density, calibrated appearance, contrast, or an image-quality score. Browser-local processing avoids a Nirmion file upload, but it cannot remove copies stored elsewhere.
MDN Canvas pixel manipulationUseful checks for image lightness distribution report
- Compare lightness balance across consistently prepared assets while using the luminance histogram for a different weighted brightness model.
- 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 Lightness Distribution 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 Lightness Distribution Report work?
Each visible RGB tuple becomes HSL lightness from channel maximum and minimum; sorted values provide linear-interpolated quartiles and a 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 Lightness Distribution Report?
HSL lightness is not Rec. 709 luminance, exposure, HDR range, print density, calibrated appearance, contrast, or an image-quality score. 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.