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Image Tools / Local studio

Image Edge Density Report

Count visible pixels whose two-axis Sobel gradient magnitude reaches a fixed threshold and report their coverage percentage.

Runs locallyNo image upload to Nirmion

Step 1 / Source

Choose one image

JPEG · PNG · WebP · 20 MB

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 megapixels

Step 2 / Output

Image Edge Density Report settings

This analysis uses one documented method so repeated runs on the same decoded pixels remain comparable.

Prepare the Sobel edge-density JSON reportThe source is not overwritten. Analysis produces a separate Sobel edge-density 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 edge density report with an inspectable review path

Horizontal and vertical 3 by 3 Sobel responses form a gradient magnitude; values at least 128 count toward visible edge coverage. Compare the result with the untouched source before using it downstream.
A

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.

B

Social-ready choices

Compare layout variants for relative edge activity while separately inspecting whether text and subject boundaries remain legible.

C

What you receive

Review and download a separate Sobel edge-density JSON report; the original file on your device remains unchanged.

Decision guide

What image edge density report measures or changes

Horizontal and vertical 3 by 3 Sobel responses form a gradient magnitude; values at least 128 count toward visible edge coverage.

A fixed decoded-pixel threshold depends on scale and texture; it does not identify objects, certify focus, or measure vector complexity. Browser-local processing avoids a Nirmion file upload, but it cannot remove copies stored elsewhere.

OpenCV Canny edge tutorial

Useful checks for image edge density report

  1. Compare layout variants for relative edge activity while separately inspecting whether text and subject boundaries remain legible.
  2. Create a bounded review result while retaining the original for comparison, correction, or a different method.
  3. 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 Edge Density 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 Edge Density Report work?

Horizontal and vertical 3 by 3 Sobel responses form a gradient magnitude; values at least 128 count toward visible edge coverage. 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 Edge Density Report?

A fixed decoded-pixel threshold depends on scale and texture; it does not identify objects, certify focus, or measure vector complexity. 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.