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Image Tools / Local studio

Image Sobel Edge Map

Measure horizontal and vertical luminance gradients locally, combine their magnitude, and export a lossless grayscale edge map.

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 Sobel Edge Map method

This workflow uses one fixed, documented method so repeated runs on the same decoded pixels are comparable. Processing stays in this browser tab.

Create the grayscale Sobel edge-map PNGThe source is not overwritten. Export creates a separate grayscale Sobel edge-map PNG.
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 sobel edge map with an inspectable review path

A pair of 3 by 3 Sobel kernels estimates horizontal and vertical luminance derivatives, then their magnitude becomes grayscale intensity. 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

Inspect whether product silhouettes and printed labels have enough edge separation before segmentation or layout review.

C

What you receive

Download a separate grayscale Sobel edge-map PNG; the original file on your device remains unchanged.

Decision guide

What image sobel edge map measures or changes

A pair of 3 by 3 Sobel kernels estimates horizontal and vertical luminance derivatives, then their magnitude becomes grayscale intensity.

Edge brightness represents local decoded-pixel gradients, not object recognition, vector tracing, focus certification, or physical boundary measurement. Browser-local processing avoids a Nirmion file upload, but it cannot remove copies stored elsewhere.

OpenCV Sobel derivatives tutorial

Useful checks for image sobel edge map

  1. Inspect whether product silhouettes and printed labels have enough edge separation before segmentation or layout review.
  2. Create a bounded review derivative 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 Sobel Edge Map upload my image?

No. For supported JPEG, PNG, and WebP inputs, 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 report, while the original file on your device remains unchanged and should be retained for comparison.

How does Image Sobel Edge Map work?

A pair of 3 by 3 Sobel kernels estimates horizontal and vertical luminance derivatives, then their magnitude becomes grayscale intensity. Existing alpha values remain available to the documented operation. The method does not infer subjects, restore missing detail, calibrate a display, or develop raw camera data. Compare fine edges, gradients, text, texture, and transparent pixels with the original before relying on the result.

What are the limits of Image Sobel Edge Map?

Edge brightness represents local decoded-pixel gradients, not object recognition, vector tracing, focus certification, or physical boundary measurement. 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.