torch v0.16.0 · OCaml Package

type 'a result = ('a, [ `Msg of string ]) Base.Result.t

Image representation

type 'kind buffer = ('a, 'b, Stdlib.Bigarray.c_layout) Stdlib.Bigarray.Array1.t constraint 'kind = ('a, 'b) Stdlib.Bigarray.kind

buffer simply is an alias to a bigarray with c_layout. The buffer type serves two purposes:

representing input files,
representing the raw pixels of an image.

Two kind of pixel buffers are manipulated:

int8 for images with 8-bit channels
float32 for images with floating point channels

type float32 = (float, Stdlib.Bigarray.float32_elt) Stdlib.Bigarray.kind

type int8 = (int, Stdlib.Bigarray.int8_unsigned_elt) Stdlib.Bigarray.kind

type 'kind t = private {

width : int;
height : int;
channels : int;
offset : int;
stride : int;
data : 'kind buffer;

}

A record describing an image. The buffer contains channels * width * height items, in this order:

channels are interleaved
each pixel is made of channels items
each line is made of width pixels
image is made of height lines

Creating image

val image : 
  width:int ->
  height:int ->
  channels:int ->
  ?offset:int ->
  ?stride:int ->
  'kind buffer ->
  'kind t result

Image accessors

val width : _ t -> int

val height : _ t -> int

val channels : _ t -> int

val data : 'kind t -> 'kind buffer

Image decoding

val load : ?channels:int -> string -> int8 t result

Load an 8-bit per channel image from a filename. If channels is specified, it has to be between 1 and 4 and the decoded image will be processed to have the requested number of channels.

val loadf : ?channels:int -> string -> float32 t result

Load a floating point channel image from a filename. See load for channels parameter.

val decode : ?channels:int -> _ buffer -> int8 t result

Decode an 8-bit per channel image from a buffer. See load for channels parameter.

val decodef : ?channels:int -> _ buffer -> float32 t result

Decode a floating point channel image from a buffer. See load for channels parameter.

Low-level interface

Functions are similar to the above one, except memory is not managed by OCaml GC. It has to be released explicitly with free_unmanaged function.

You get slightly faster load times, more deterministic memory use and more responsibility. Use at your own risk!

val load_unmanaged : ?channels:int -> string -> int8 t result

val loadf_unmanaged : ?channels:int -> string -> float32 t result

val decode_unmanaged : ?channels:int -> _ buffer -> int8 t result

val decodef_unmanaged : ?channels:int -> _ buffer -> float32 t result

val free_unmanaged : _ t -> unit

Image filtering

val mipmap : int8 t -> int8 t -> unit

Generate one level of mipmap: downsample image half in each dimension. In mipmap imgin imgout:

imgout.channels must be imgin.channels
imgout.width must be imgin.width / 2
imgout.height must be imgin.height / 2
imgout.data will be filled with downsampled imgin.data

val mipmapf : float32 t -> float32 t -> unit

Downsample floating point images. See mipmap.

val vflip : int8 t -> unit

Flip the image vertically

val vflipf : float32 t -> unit