Enums

All enumerations in the PhpMlKit\Opal namespace.

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Kernel

Resampling kernel used for image resize/scale operations. Maps directly to VIPS VipsKernel.

Default across the library is Lanczos3, which offers high-quality down- and up-sampling. Use a lighter kernel ( e.g. Linear or Nearest) when throughput matters more than fidelity.

enum Kernel: string

Cases

Case	Value	Description
Nearest	'nearest'	Nearest-neighbour — fast, blocky. Useful for pixel-art.
Linear	'linear'	Bilinear interpolation — smooth, moderate quality.
Cubic	'cubic'	Bicubic interpolation — sharper than linear.
Mitchell	'mitchell'	Mitchell-Netravalli filter — good general-purpose.
Lanczos2	'lanczos2'	2-lobe Lanczos — sharp with mild ringing.
Lanczos3	'lanczos3'	3-lobe Lanczos — high quality, default kernel.
Mks211	'mks211'	MKS 211 kernel — 2-lobe MKS filter.
Mks213	'mks213'	MKS 213 kernel — 3-lobe MKS filter.

Used in: Image::resize(), Image::resizeToWidth(), Image::resizeToHeight(), Image::scale()

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ColorSpace

Supported color spaces. Backed by vips interpretation strings.

enum ColorSpace: string

Cases

Case	Value	Bands
RGB	'rgb'	3
RGBA	'rgba'	4
BGR	'bgr'	3
BGRA	'bgra'	4
Grayscale	'grey'	1
Lab	'lab'	3
HSV	'hsv'	3
CMYK	'cmyk'	4

Methods

bands()

Returns the number of channels for a newly created image in this space.

public function bands(): int

fromVipsInterpretation()

Create a ColorSpace from a VIPS interpretation string.

public static function fromVipsInterpretation(string $interpretation): ColorSpace

toVipsInterpretation()

Convert to a VIPS interpretation string.

public function toVipsInterpretation(): string

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BandFormat

Enumeration of supported numeric formats for pixel bands. Each value represents a data type used to store per-channel pixel information.

enum BandFormat: int

Cases

Case	Value	Storage (bytes)	NDArray DType
UCHAR	0	1	UInt8
CHAR	1	1	Int8
USHORT	2	2	UInt16
SHORT	3	2	Int16
UINT	4	4	UInt32
INT	5	4	Int32
FLOAT	6	4	Float32
COMPLEX	7	8	Complex64
DOUBLE	8	8	Float64
DPCOMPLEX	9	16	Complex128

Methods

fromString()

public static function fromString(string $format): self

toString()

public function toString(): string

fromDtype()

Create from an NDArray DType.

public static function fromDtype(DType $dtype): self

Throws: \InvalidArgumentException if the dtype is unsupported.

toDtype()

Convert to an NDArray DType.

public function toDtype(): DType

storageBytes()

Returns the number of bytes per pixel band.

public function storageBytes(): int

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FlipDirection

Axis to flip an image along.

enum FlipDirection

Cases

Case	Description
Horizontal	Flip left-to-right
Vertical	Flip top-to-bottom
Both	Flip along both axes

Used in: Image::flip()

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ChannelFormat

Memory layout for multichannel image tensors when importing/exporting NDArray.

enum ChannelFormat

Cases

Case	Layout	Description
HWC	[height, width, channels]	TensorFlow / NumPy / PIL default
CHW	[channels, height, width]	PyTorch / ONNX vision default

Used in: Image::fromArray(), Image::toArray()

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ImageFormat

Image file container formats.

enum ImageFormat: string

Cases

Case	Value	Extension
JPEG	'jpeg'	.jpg
PNG	'png'	.png
WebP	'webp'	.webp
TIFF	'tiff'	.tif
GIF	'gif'	.gif
BMP	'bmp'	.bmp
AVIF	'avif'	.avif
HEIF	'heif'	.heif

Methods

fromExtension()

public static function fromExtension(string $extension): self

Throws: UnsupportedFormatException if the extension is not recognized.

toExtension()

public function toExtension(): string

suffix()

Returns the file suffix including the leading dot.

public function suffix(): string