pyrUp

Image processingfunctionOpenCV 5.0.0

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

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

Explore visually: Gaussian and Laplacian pyramids →

A Gaussian pyramid keeps smaller, blurrier copies of an image. A Laplacian pyramid keeps the detail lost between those copies, plus the smallest copy needed to rebuild the image.

VISUAL WALKTHROUGHFiltering

REFERENCE INPUTOriginal: broad shapes + fine stripes

Watch the thin stripes inside the rectangle. Shrinking removes their contrast while the larger shapes remain recognizable.

→

RESULTRebuild: enlarge, add detail, repeat

Start with the saved G2. Expand it and add L1 to recover G1; expand again and add L0 to recover G0. Enlarging alone leaves a blur. Adding the stored signed detail bands restores every original sample in this floating-point example.

Computed 32 × 24 example using the OpenCV pyramid kernel, checked against native pyrDown/pyrUp. Detail-band colour is amplified 3× for visibility; the stored values keep their signs and are never clipped.

Upsamples an image and then blurs it.

By default, size of the output image is computed as Size(src.cols\*2, (src.rows\*2), but in any case, the following conditions should be satisfied:

\begin{array}{l} | \texttt{dstsize.width} -src.cols*2| \leq  ( \texttt{dstsize.width}   \mod  2)  \\ | \texttt{dstsize.height} -src.rows*2| \leq  ( \texttt{dstsize.height}   \mod  2) \end{array}

The function performs the upsampling step of the Gaussian pyramid construction, though it can actually be used to construct the Laplacian pyramid. First, it upsamples the source image by injecting even zero rows and columns and then convolves the result with the same kernel as in pyrDown multiplied by 4.

pyrUp(src: Mat, dst: Mat, dstsize: Size, borderType: number): void;

3 available overloads

pyrUp(src: Mat, dst: Mat): void;

pyrUp(src: Mat, dst: Mat, dstsize: Size): void;

pyrUp(src: Mat, dst: Mat, dstsize: Size, borderType: number): void;

src

input image.

dst

Output destination, filled by the native operation. output image. It has the specified size and the same type as src .

dstsize

size of the output image.

borderType

Pixel extrapolation method, see #BorderTypes (only #BORDER_DEFAULT is supported)

Upstream declaration ↗

These signatures describe this package. Upstream documentation can mention optional backends that are absent from this build. Check runtime compatibility before choosing a backend or file format.