copyMakeBorder

Core and matricesfunctionOpenCV 5.0.0

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

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

ARGUMENTSsrc, dst, top, bottom

FUNCTIONcopyMakeBorder

RETURN TYPEvoid

Call structure. A void return can still write to destination arguments. The parameter descriptions define inputs, outputs and ownership.

example: samples/cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp An example using copyMakeBorder function. Check tutorial_copyMakeBorder "the corresponding tutorial" for more details Forms a border around an image.

The function copies the source image into the middle of the destination image. The areas to the left, to the right, above and below the copied source image will be filled with extrapolated pixels. This is not what filtering functions based on it do (they extrapolate pixels on-fly), but what other more complex functions, including your own, may do to simplify image boundary handling.

The function supports the mode when src is already in the middle of dst . In this case, the function does not copy src itself but simply constructs the border, for example:

    // let border be the same in all directions
    int border=2;
    // constructs a larger image to fit both the image and the border
    Mat gray_buf(rgb.rows + border*2, rgb.cols + border*2, rgb.depth());
    // select the middle part of it w/o copying data
    Mat gray(gray_canvas, Rect(border, border, rgb.cols, rgb.rows));
    // convert image from RGB to grayscale
    cvtColor(rgb, gray, COLOR_RGB2GRAY);
    // form a border in-place
    copyMakeBorder(gray, gray_buf, border, border,
                   border, border, BORDER_REPLICATE);
    // now do some custom filtering ...
    ...

Note: When the source image is a part (ROI) of a bigger image, the function will try to use the pixels outside of the ROI to form a border. To disable this feature and always do extrapolation, as if src was not a ROI, use borderType | #BORDER_ISOLATED.

See: borderInterpolate

copyMakeBorder(src: Mat, dst: Mat, top: number, bottom: number, left: number, right: number, borderType: number, value: Scalar): void;

2 available overloads

copyMakeBorder(src: Mat, dst: Mat, top: number, bottom: number, left: number, right: number, borderType: number): void;

copyMakeBorder(src: Mat, dst: Mat, top: number, bottom: number, left: number, right: number, borderType: number, value: Scalar): void;

src: Source image.
dst: Output destination, filled by the native operation. Destination image of the same type as src and the size Size(src.cols+left+right, src.rows+top+bottom) .
top: the top pixels
bottom: the bottom pixels
left: the left pixels
right: Parameter specifying how many pixels in each direction from the source image rectangle to extrapolate. For example, top=1, bottom=1, left=1, right=1 mean that 1 pixel-wide border needs to be built.
borderType: Border type. See borderInterpolate for details.
value: Border value if borderType==BORDER_CONSTANT .

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.