doc: introduce jpeg_encode and jpeg_decode

Author: johnnychen94

README.md

@@ -4,3 +4,44 @@
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://johnnychen94.github.io/JpegTurbo.jl/dev)
 [![Build Status](https://github.com/johnnychen94/JpegTurbo.jl/actions/workflows/UnitTest.yml/badge.svg?branch=master)](https://github.com/johnnychen94/JpegTurbo.jl/actions/workflows/UnitTest.yml?query=branch%3Amaster)
 [![Coverage](https://codecov.io/gh/johnnychen94/JpegTurbo.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/johnnychen94/JpegTurbo.jl)
+
+JpegTurbo.jl is a Julia wrapper of the C library [libjpeg-turbo] that provides IO support for
+the JPEG image format.
+
+The main functionality of this package consist of two functions: `jpeg_encode` and `jpeg_decode`.
+Check the [function references](https://johnnychen94.github.io/JpegTurbo.jl/dev/reference) for more
+details.
+
+## API
+
+`jpeg_encode` is used to compress 2D colorant matrix as JPEG image.
+
+```julia
+jpeg_encode(filename::AbstractString, img; kwargs...) -> Int
+jpeg_encode(io::IO, img; kwargs...) -> Int
+jpeg_encode(img; kwargs...) -> Vector{UInt8}
+```
+
+`jpeg_decode` is used to decompress JPEG image as 2D colorant matrix.
+
+```julia
+jpeg_decode([T,] filename::AbstractString; kwargs...) -> Matrix{T}
+```
+
+## Feature set
+
+| function             | filename | IOStream | in-memory buffer     | pre-allocated output | multi-threads |
+| -------------------- | -------- | -------- | -------------------- | -------------------  | ------------- |
+| `jpeg_encode`        | x        | x        | x                    |                      | x             |
+| `jpeg_decode`        | x        |          |                      |                      | x             |
+| `ImageMagick.save`   | x        | x        | x                    |                      | x             |
+| `ImageMagick.load`   | x        | x        | x                    |                      | x             |
+| `QuartzImageIO.save` | x        | x        | x (`FileIO.Stream`)  |                      | x             |
+| `QuartzImageIO.load` | x        | x        | x (`FileIO.Stream`)  |                      | x             |
+
+Notes:
+
+- `x`: supported
+- empty: missing/unsupported yet
+
+[libjpeg-turbo]: https://github.com/libjpeg-turbo/libjpeg-turbo

docs/src/index.md

@@ -1,3 +1,41 @@
 # JpegTurbo
 
-Documentation for [JpegTurbo](https://github.com/johnnychen94/JpegTurbo.jl).
+[JpegTurbo.jl](https://github.com/johnnychen94/JpegTurbo.jl) is a Julia wrapper of the C library
+[libjpeg-turbo](https://github.com/libjpeg-turbo/libjpeg-turbo) that provides IO support for the
+JPEG image format.
+
+The main functionality of this package consist of two functions: `jpeg_encode` and `jpeg_decode`.
+Check the [function references](@Function-references) for more details.
+
+## API
+
+`jpeg_encode` is used to compress 2D colorant matrix as JPEG image.
+
+```julia
+jpeg_encode(filename::AbstractString, img; kwargs...) -> Int
+jpeg_encode(io::IO, img; kwargs...) -> Int
+jpeg_encode(img; kwargs...) -> Vector{UInt8}
+```
+
+`jpeg_decode` is used to decompress JPEG image as 2D colorant matrix.
+
+```julia
+jpeg_decode([T,] filename::AbstractString; kwargs...) -> Matrix{T}
+```
+
+## Feature set
+
+| function             | filename | IOStream | in-memory buffer     | pre-allocated output | multi-threads |
+| -------------------- | -------- | -------- | -------------------- | -------------------  | ------------- |
+| `jpeg_encode`        | x        | x        | x                    |                      | x             |
+| `jpeg_decode`        | x        |          |                      |                      | x             |
+| `ImageMagick.save`   | x        | x        | x                    |                      | x             |
+| `ImageMagick.load`   | x        | x        | x                    |                      | x             |
+| `QuartzImageIO.save` | x        | x        | x (`FileIO.Stream`)  |                      | x             |
+| `QuartzImageIO.load` | x        | x        | x (`FileIO.Stream`)  |                      | x             |
+
+Notes:
+
+- `x`: supported
+- empty: missing/unsupported yet
+