PHP Manual: imagescale

function imagescale(
    GdImage $image,
    int $width,
    int $height = -1,
    int $mode = IMG_BILINEAR_FIXED
): GdImage|false

imagescale() scales an image using the given interpolation algorithm.

Note:
Unlike many of other image functions, imagescale() does not modify the passed image; instead, a new image is returned.

image

A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().

width

The width to scale the image to.

height

The height to scale the image to. If omitted or negative, the aspect ratio will be preserved.

mode

One of IMG_NEAREST_NEIGHBOUR, IMG_BILINEAR_FIXED, IMG_BICUBIC, IMG_BICUBIC_FIXED or anything else (will use two pass).

Note:
IMG_WEIGHTED4 is not yet supported.

Return the scaled image object on success or false on failure.

Throws a ValueError if width or height would cause over-/underflow.

Throws a ValueError if mode is invalid.

Version	Description
8.4.0	Now throws a ValueError if `width` or `height` would cause over-/underflow.
8.4.0	Now throws a ValueError if `mode` is invalid.
8.0.0	On success, this function returns a GDImage instance now; previously, a resource was returned.
8.0.0	`image` expects a GdImage instance now; previously, a valid `gd` resource was expected.

imagescale