How to Apply a Gaussian Blur to an Image

What the image blur tool does

Image Blur applies a Gaussian blur to supplied image data and lets you choose the blur radius. This is useful when you want to soften visual detail or create a blurred version of a picture for a design, mockup, or other image-based task.

The image file is optional as an input, but processing cannot begin with empty image data. Supplying a readable image gives the operation content to decode, open, filter, and save. If you do not enter a different numeric setting, the blur radius starts at 5.0.

How to blur an image

1. Select the image file that you want to process. Use supplied image data that can be decoded and opened as an image, because problems at either stage can prevent the operation from completing.
2. Enter a numeric blur radius when you want to change the starting setting. Leaving the radius unchanged uses the default value of 5.0.
3. Check the value before running the operation. A supplied radius below 0.1 is raised to an effective value of 0.1 for the blur operation, so a value under that threshold is not used unchanged.
4. Start the image-processing operation after the image and radius are ready. The operation applies the Gaussian blur to the supplied image data.
5. Review the returned result after processing finishes. A successful result provides encoded blurred image data and reports the original image dimensions.
6. Identify the output format from the result when you need to work with the encoded data. The detected input format is preserved when it is available; when it is not available, the result uses PNG.

If the operation reports a failure, verify the image input and try again with image data that can be opened. Failures can also occur during filtering or saving, or when the required image-processing dependency is unavailable.

How to read the result

Use the selected radius as the setting that controls the Gaussian blur operation, and choose it based on the amount of detail you want to soften. A value below 0.1 is treated as 0.1 for the operation, which gives you a clear lower boundary when entering a very small number.

A successful result has two useful parts to inspect: encoded image data containing the blurred picture and the original image dimensions. The format normally follows the detected input format, while PNG is used when that format is unavailable. The reported dimensions describe the source image associated with the processed result.

A missing image is not a successful empty-input case. Processing may fail if the data cannot be decoded or opened, if filtering or saving raises an error, or if the required image-processing dependency is unavailable. These boundaries mean that a returned result should be checked rather than assumed after the operation starts.

Worked example

You want to soften facial detail in a portrait before using the processed image in a design.

Select a portrait image, enter a radius of 8.0, and start the blur operation.

A successful result contains encoded blurred image data and reports the original image dimensions; the detected input format is preserved when available, otherwise the result uses PNG.

Limitations

• Processing can fail for empty or unreadable image data, decoding and conversion problems, filtering or saving errors, or an unavailable required image-processing dependency.

Common errors

• If the image field is left empty, processing fails; select and supply an image file before starting the operation.

FAQ

What is the default blur radius?

When you leave the radius unchanged, the operation uses 5.0 as its default numeric setting.

What happens when the blur radius is below 0.1?

A supplied value below 0.1 is raised to an effective value of 0.1 during the blur operation.

Why can image blurring fail?

Failure can result from empty image data, decoding or opening problems, an error during filtering or saving, or an unavailable required image-processing dependency.