bilateralFilter

Image processingfunctionOpenCV 5.0.0

import { bilateralFilter } from '@banou/opencv-wasm'

Use after await initOpenCV(). See the initialization and named imports guide.

Explore visually: Bilateral filtering →

Smooth nearby pixels only when their colours are also similar.

VISUAL WALKTHROUGHFiltering

REFERENCE INPUTNoisy or uneven image

The same scene stays here while the working view changes.

→

RESULTApply the rule at every pixel

The whole image has now been processed. The highlighted input value 156 becomes 152.9.

Computed teaching example on a 24 × 16 image. Small kernels and simplified settings keep each change visible; use the image laboratory for native OpenCV.

Applies the bilateral filter to an image.

The function applies bilateral filtering to the input image, as described in https://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/MANDUCHI1/Bilateral_Filtering.html bilateralFilter can reduce unwanted noise very well while keeping edges fairly sharp. However, it is very slow compared to most filters.

Sigma values: For simplicity, you can set the 2 sigma values to be the same. If they are small (< 10), the filter will not have much effect, whereas if they are large (> 150), they will have a very strong effect, making the image look "cartoonish".

Filter size: Large filters (d > 5) are very slow, so it is recommended to use d=5 for real-time applications, and perhaps d=9 for offline applications that need heavy noise filtering.

This filter does not work inplace.

bilateralFilter(src: Mat, dst: Mat, d: number, sigmaColor: number, sigmaSpace: number, borderType: number): void;

2 available overloads

bilateralFilter(src: Mat, dst: Mat, d: number, sigmaColor: number, sigmaSpace: number): void;

bilateralFilter(src: Mat, dst: Mat, d: number, sigmaColor: number, sigmaSpace: number, borderType: number): void;

src

Source 8-bit or floating-point, 1-channel or 3-channel image.

dst

Output destination, filled by the native operation. Destination image of the same size and type as src .

d

Diameter of each pixel neighborhood that is used during filtering. If it is non-positive, it is computed from sigmaSpace.

sigmaColor

Filter sigma in the color space. A larger value of the parameter means that farther colors within the pixel neighborhood (see sigmaSpace) will be mixed together, resulting in larger areas of semi-equal color.

sigmaSpace

Filter sigma in the coordinate space. A larger value of the parameter means that farther pixels will influence each other as long as their colors are close enough (see sigmaColor ). When d>0, it specifies the neighborhood size regardless of sigmaSpace. Otherwise, d is proportional to sigmaSpace.

borderType

border mode used to extrapolate pixels outside of the image, see #BorderTypes

Upstream declaration ↗

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