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Updated documentation to include mlpack image utilities

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adithya-tp committed Jan 7, 2020
1 parent 16ee2fa commit 63d9ca628af7de1b1244311e7255268ed628e962
Showing with 145 additions and 186 deletions.
  1. +145 −1 doc/guide/formats.hpp
  2. +0 −185 doc/tutorials/image/image.txt
@@ -2,11 +2,36 @@
@section formatintro Introduction
mlpack supports a wide variety of data and model formats for use in both its
mlpack supports a wide variety of data (including images) and model formats for use in both its
command-line programs and in C++ programs using mlpack via the
mlpack::data::Load() function. This tutorial discusses the formats that are
supported and how to use them.
@section toc_tut Table of Contents
This tutorial is split into the following sections:
- \ref formatintro
- \ref toc_tut
- Data
- Data Formats
- \ref formatsimple
- \ref formattypes
- \ref formatcpp
- \ref sparseload
- \ref formatcat
- \ref formatcatcpp
- Image Support
- \ref intro_imagetut
- \ref model_api_imagetut
- \ref imageinfo_api_imagetut
- \ref load_api_imagetut
- \ref save_api_imagetut
- Models
- \ref formatmodels
- \ref formatmodelscpp
- \ref formatfinal
@section formatsimple Simple examples to load data in C++
The example code snippets below load data from different formats into an
@@ -295,6 +320,125 @@ mlpack::data::Save("dataset-new.tsv", dataset, info);
There is more functionality to the DatasetInfo class; for more information, see
the mlpack::data::DatasetInfo documentation.
@section intro_imagetut Loading and Saving Images
Image datasets are becoming increasingly popular in deep learning.
mlpack's image saving/loading functionality is based on [stb/](https://github.com/nothings/stb).
@section model_api_imagetut Image Utilities API
Image utilities supports loading and saving of images.
It supports filetypes "jpg", "png", "tga","bmp", "psd", "gif", "hdr", "pic", "pnm" for loading and "jpg", "png", "tga", "bmp", "hdr" for saving.
The datatype associated is unsigned char to support RGB values in the range 1-255. To feed data into the network typecast of `arma::Mat` may be required. Images are stored in matrix as (width * height * channels, NumberOfImages). Therefore imageMatrix.col(0) would be the first image if images are loaded in imageMatrix.
@section imageinfo_api_imagetut Accessing Metadata of Images: ImageInfo
ImageInfo class contains the metadata of the images.
@code
ImageInfo(const size_t width,
const size_t height,
const size_t channels);
@endcode
Other public memebers include:
- flipVertical Flip the image vertical upon loading.
- quality Compression of the image if saved as jpg (0-100).
@section load_api_imagetut Loading Images in C++
Standalone loading of images.
@code
template<typename eT>
bool Load(const std::string& filename,
arma::Mat<eT>& matrix,
ImageInfo& info,
const bool fatal,
const bool transpose);
@endcode
Loading a test image. It also fills up the ImageInfo class object.
@code
data::ImageInfo info;
data::Load("test_image.png", matrix, info, false, true);
@endcode
ImageInfo requires height, width, number of channels of the image.
@code
size_t height = 64, width = 64, channels = 1;
data::ImageInfo info(width, height, channels);
@endcode
More than one image can be loaded into the same matrix.
Loading multiple images:
@code
template<typename eT>
bool Load(const std::vector<std::string>& files,
arma::Mat<eT>& matrix,
ImageInfo& info,
const bool fatal,
const bool transpose);
@endcode
@code
data::ImageInfo info;
std::vector<std::string>> files{"test_image1.bmp","test_image2.bmp"};
data::load(files, matrix, info, false, true);
@endcode
@section save_api_imagetut Saving Images in C++
Save images expects a matrix of type unsigned char in the form (width * height * channels, NumberOfImages).
Just like load it can be used to save one image or multiple images. Besides image data it also expects the shape of the image as input (width, height, channels).
Saving one image:
@code
template<typename eT>
bool Save(const std::string& filename,
arma::Mat<eT>& matrix,
ImageInfo& info,
const bool fatal,
const bool transpose);
@endcode
@code
data::ImageInfo info;
info.width = info.height = 25;
info.channels = 3;
info.quality = 90;
data::Save("test_image.bmp", matrix, info, false, true);
@endcode
If the matrix contains more than one image, only the first one is saved.
Saving multiple images:
@code
template<typename eT>
bool Save(const std::vector<std::string>& files,
arma::Mat<eT>& matrix,
ImageInfo& info,
const bool fatal,
const bool transpose);
@endcode
@code
data::ImageInfo info;
info.width = info.height = 25;
info.channels = 3;
info.quality = 90;
std::vector<std::string>> files{"test_image1.bmp", "test_image2.bmp"};
data::Save(files, matrix, info, false, true);
@endcode
Multiple images are saved according to the vector of filenames specified.
@section formatmodels Loading and saving models
Using \c boost::serialization, mlpack is able to load and save machine learning

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