Add Pascal VOC Datasets for image detection and segmentation (#209)

Author: DerrickUnleashed

DESCRIPTION

@@ -51,5 +51,6 @@ Suggests:
     magick,
     testthat,
     coro,
-    R.matlab
+    R.matlab,
+    xml2
 BugReports: https://github.com/mlverse/torchvision/issues

NAMESPACE

@@ -142,6 +142,8 @@ export(nms)
 export(oxfordiiitpet_binary_dataset)
 export(oxfordiiitpet_dataset)
 export(oxfordiiitpet_segmentation_dataset)
+export(pascal_detection_dataset)
+export(pascal_segmentation_dataset)
 export(places365_dataset)
 export(places365_dataset_large)
 export(qmnist_dataset)

NEWS.md

@@ -3,6 +3,8 @@
 ## New datasets
 
 * Added `lfw_people_dataset()` and `lfw_pairs_dataset()` for loading Labelled Faces in the Wild (LFW) datasets (@DerrickUnleashed, #203).
+* Added `places365_dataset()`for loading the Places365 dataset (@koshtiakanksha, #196).
+* Added `pascal_segmentation_dataset()`, and `pascal_detection_dataset()` for loading the Pascal Visual Object Classes datasets (@DerrickUnleashed, #209).
 
 ## New models
 

R/dataset-pascal.R

@@ -0,0 +1,355 @@
+#' Pascal VOC Segmentation Dataset
+#'
+#' The Pascal Visual Object Classes (VOC) dataset is a widely used benchmark for object detection and semantic segmentation tasks in computer vision.
+#'
+#' This dataset provides RGB images along with per-pixel class segmentation masks for 20 object categories, plus a background class.
+#' Each pixel in the mask is labeled with a class index corresponding to one of the predefined semantic categories.
+#'
+#' The VOC dataset was released in yearly editions (2007 to 2012), with slight variations in data splits and annotation formats.
+#' Notably, only the 2007 edition includes a separate `test` split; all other years (2008–2012) provide only the `train`, `val`, and `trainval` splits.
+#'
+#' The dataset defines 21 semantic classes: `"background"`, `"aeroplane"`, `"bicycle"`, `"bird"`, `"boat"`, `"bottle"`, `"bus"`, `"car"`, `"cat"`, `"chair"`,
+#' `"cow"`, `"dining table"`, `"dog"`, `"horse"`, `"motorbike"`, `"person"`, `"potted plant"`, `"sheep"`, `"sofa"`, `"train"`, and `"tv/monitor"`.
+#' They are available through the `classes` variable of the dataset object.
+#'
+#' This dataset is frequently used for training and evaluating semantic segmentation models, and supports tasks requiring dense, per-pixel annotations.
+#'
+#' @inheritParams oxfordiiitpet_dataset
+#' @param root Character. Root directory where the dataset will be stored under `root/pascal_voc_<year>`.
+#' @param year Character. VOC dataset version to use. One of `"2007"`, `"2008"`, `"2009"`, `"2010"`, `"2011"`, or `"2012"`. Default is `"2012"`.
+#' @param split Character. One of `"train"`, `"val"`, `"trainval"`, or `"test"`. Determines the dataset split. Default is `"train"`.
+#'
+#' @return A torch dataset of class \code{pascal_segmentation_dataset}.
+#'
+#' The returned list inherits class \code{image_with_segmentation_mask}, which allows generic visualization
+#' utilities to be applied.
+#'
+#' Each element is a named list with the following structure:
+#' - `x`: a H x W x 3 array representing the RGB image.
+#' - `y`: A named list containing:
+#'     - `masks`: A `torch_tensor` of dtype `bool` and shape `(21, H, W)`, representing a multi-channel segmentation mask.
+#'       Each of the 21 channels corresponds to a Pascal VOC classes
+#'     - `labels`: An integer vector indicating the indices of the classes present in the mask.
+#'
+#' @examples
+#' \dontrun{
+#' # Load Pascal VOC segmentation dataset (2007 train split)
+#' pascal_seg <- pascal_segmentation_dataset(
+#'  transform = transform_to_tensor,
+#'  download = TRUE,
+#'  year = "2007"
+#' )
+#'
+#' # Access the first image and its mask
+#' first_item <- pascal_seg[1]
+#' first_item$x  # Image
+#' first_item$y$masks  # Segmentation mask
+#' first_item$y$labels  # Unique class labels in the mask
+#' pascal_seg$classes[first_item$y$labels]  # Class names
+#'
+#' # Visualise the first image and its mask
+#' masked_img <- draw_segmentation_masks(first_item)
+#' tensor_image_browse(masked_img)
+#'
+#' # Load Pascal VOC detection dataset (2007 train split)
+#' pascal_det <- pascal_detection_dataset(
+#'  transform = transform_to_tensor,
+#'  download = TRUE,
+#'  year = "2007"
+#' )
+#'
+#' # Access the first image and its bounding boxes
+#' first_item <- pascal_det[1]
+#' first_item$x  # Image
+#' first_item$y$labels  # Object labels
+#' first_item$y$boxes  # Bounding box tensor
+#'
+#' # Visualise the first image with bounding boxes
+#' boxed_img <- draw_bounding_boxes(first_item)
+#' tensor_image_browse(boxed_img)
+#' }
+#'
+#' @name pascal_voc_datasets
+#' @title Pascal VOC Datasets
+#' @rdname pascal_voc_datasets
+#' @family segmentation_dataset
+#' @export
+pascal_segmentation_dataset <- torch::dataset(
+  name = "pascal_segmentation_dataset",
+
+  resources = data.frame(
+    year = c("2007", "2007", "2008", "2009", "2010", "2011", "2012"),
+    type = c("trainval", "test", "trainval", "trainval", "trainval", "trainval", "trainval"),
+    url = c("https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_06-Nov-2007.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtest_06-Nov-2007.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_14-Jul-2008.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_11-May-2009.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_03-May-2010.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_25-May-2011.tar",
+            "https://huggingface.co/datasets/JimmyUnleashed/Pascal_VOC/resolve/main/VOCtrainval_11-May-2012.tar"),
+    md5 = c("c52e279531787c972589f7e41ab4ae64",
+            "b6e924de25625d8de591ea690078ad9f",
+            "2629fa636546599198acfcfbfcf1904a",
+            "59065e4b188729180974ef6572f6a212",
+            "da459979d0c395079b5c75ee67908abb",
+            "6c3384ef61512963050cb5d687e5bf1e",
+            "6cd6e144f989b92b3379bac3b3de84fd"),
+    size = c("440 MB", "440 MB", "550 MB", "890 MB", "1.3 GB", "1.7 GB", "1.9 GB")
+  ),
+  classes = c(
+    "background", "aeroplane", "bicycle", "bird", "boat",
+    "bottle", "bus", "car", "cat", "chair",
+    "cow", "dining table", "dog", "horse", "motorbike",
+    "person", "potted plant", "sheep", "sofa", "train",
+    "tv/monitor"
+  ),
+  voc_colormap = c(
+    c(0, 0, 0), c(128, 0, 0), c(0, 128, 0), c(128, 128, 0),
+    c(0, 0, 128), c(128, 0, 128), c(0, 128, 128), c(128, 128, 128),
+    c(64, 0, 0), c(192, 0, 0), c(64, 128, 0), c(192, 128, 0),
+    c(64, 0, 128), c(192, 0, 128), c(64, 128, 128), c(192, 128, 128),
+    c(0, 64, 0), c(128, 64, 0), c(0, 192, 0), c(128, 192, 0),
+    c(0, 64, 128)
+  ),
+
+  initialize = function(
+    root = tempdir(),
+    year = "2012",
+    split = "train",
+    transform = NULL,
+    target_transform = NULL,
+    download = FALSE
+  ) {
+    self$root_path <- root
+    self$year <- match.arg(year, choices = unique(self$resources$year))
+    self$split <-  match.arg(split, choices = c("train", "val", "trainval", "test"))
+    self$transform <- transform
+    self$target_transform <- target_transform
+    if (self$split == "test"){
+        self$archive_key <- "test"
+    } else {
+        self$archive_key <- "trainval"
+    }
+    self$archive_size <- self$resources[self$resources$year == self$year & self$resources$type == self$archive_key,]$size
+
+    if (download) {
+      cli_inform("Dataset {.cls {class(self)[[1]]}} (~{.emph {self$archive_size}}) will be downloaded and processed if not already available.")
+      self$download()
+    }
+
+    if (!self$check_exists()) {
+      cli_abort("Dataset not found. You can use `download = TRUE` to download it.")
+    }
+
+    data_file <- file.path(self$processed_folder, paste0(self$split, ".rds"))
+    data <- readRDS(data_file)
+    self$img_path <- data$img_path
+    self$mask_paths <- data$mask_paths
+
+    cli_inform("{.cls {class(self)[[1]]}} dataset loaded with {length(self$img_path)} images across {length(self$classes)} classes.")
+  },
+
+  download = function() {
+
+    if (self$check_exists()) {
+      return()
+    }
+
+    cli_inform("Downloading {.cls {class(self)[[1]]}}...")
+
+    fs::dir_create(self$raw_folder)
+    fs::dir_create(self$processed_folder)
+
+    resource <- self$resources[self$resources$year == self$year & self$resources$type == self$archive_key,]
+    archive <- download_and_cache(resource$url, prefix = class(self)[1])
+    actual_md5 <- tools::md5sum(archive)
+
+    if (actual_md5 != resource$md5) {
+      runtime_error("Corrupt file! Delete the file in {archive} and try again.")
+    }
+
+    utils::untar(archive, exdir = self$raw_folder)
+
+    voc_dir <- file.path(self$raw_folder, "VOCdevkit", paste0("VOC", self$year))
+    voc_root <- self$raw_folder
+    if (self$year == "2011") {
+    voc_root <- file.path(voc_root, "TrainVal")
+    }
+    voc_dir <- file.path(voc_root, "VOCdevkit", paste0("VOC", self$year))
+
+    split_file <- file.path(voc_dir, "ImageSets", "Segmentation", paste0(self$split, ".txt"))
+
+    ids <- readLines(split_file)
+    img_path <- file.path(voc_dir, "JPEGImages", paste0(ids, ".jpg"))
+    mask_paths <- file.path(voc_dir, "SegmentationClass", paste0(ids, ".png"))
+
+    saveRDS(list(
+      img_path = img_path,
+      mask_paths = mask_paths
+    ), file.path(self$processed_folder, paste0(self$split, ".rds")))
+
+    cli_inform("Dataset {.cls {class(self)[[1]]}} downloaded and extracted successfully.")
+  },
+
+  check_exists = function() {
+    fs::file_exists(file.path(self$processed_folder, paste0(self$split, ".rds")))
+  },
+
+  .getitem = function(index) {
+
+    img_path <- self$img_path[index]
+    mask_path <- self$mask_paths[index]
+
+    x <- jpeg::readJPEG(img_path)
+    mask_data <- png::readPNG(mask_path) * 255
+
+    flat_mask <- matrix(
+      c(as.vector(mask_data[, , 1]),
+        as.vector(mask_data[, , 2]),
+        as.vector(mask_data[, , 3])),
+      ncol = 3
+    )
+    colormap_mat <- matrix(self$voc_colormap, ncol = 3, byrow = TRUE)
+    rgb_to_int <- function(mat) {
+      as.integer(mat[, 1]) * 256^2 + as.integer(mat[, 2]) * 256 + as.integer(mat[, 3])
+    }
+    match_indices <- match(rgb_to_int(flat_mask), rgb_to_int(colormap_mat)) - 1
+    class_idx <- matrix(match_indices, nrow = dim(mask_data)[1], ncol = dim(mask_data)[2])
+    class_idx_tensor <- torch_tensor(class_idx, dtype = torch_long())
+    class_ids <- torch_arange(0, 20, dtype = torch_long())$view(c(21, 1, 1))
+    masks <- (class_ids == class_idx_tensor$unsqueeze(1))$to(dtype = torch_bool())
+    labels <- which(as_array(masks$any(dim = c(2, 3))))
+
+    y <- list(labels = labels, masks = masks)
+
+    if (!is.null(self$transform)) {
+      x <- self$transform(x)
+    }
+    if (!is.null(self$target_transform)) {
+      y <- self$target_transform(y)
+    }
+
+    structure(list(x = x, y = y), class = "image_with_segmentation_mask")
+  },
+
+  .length = function() {
+    length(self$img_path)
+  },
+
+  active = list(
+    raw_folder = function() {
+      file.path(self$root_path, paste0("pascal_voc_", self$year), "raw")
+    },
+    processed_folder = function() {
+      file.path(self$root_path, paste0("pascal_voc_", self$year), "processed")
+    }
+  )
+)
+
+#' Pascal VOC Detection Dataset
+#'
+#' @inheritParams pascal_segmentation_dataset
+#'
+#' @return A torch dataset of class \code{pascal_detection_dataset}.
+#'
+#' The returned list inherits class \code{image_with_bounding_box}, which allows generic visualization
+#' utilities to be applied.
+#'
+#' Each element is a named list:
+#' - `x`: a H x W x 3 array representing the RGB image.
+#' - `y`: a list with:
+#'     - `labels`: a character vector with object class names.
+#'     - `boxes`: a tensor of shape (N, 4) with bounding box coordinates in `(xmin, ymin, xmax, ymax)` format.
+#'
+#' @rdname pascal_voc_datasets
+#' @family detection_dataset
+#' @export
+pascal_detection_dataset <- torch::dataset(
+  name = "pascal_detection_dataset",
+
+  inherit = pascal_segmentation_dataset,
+
+  initialize = function(
+    root = tempdir(),
+    year = "2012",
+    split = "train",
+    transform = NULL,
+    target_transform = NULL,
+    download = FALSE
+  ) {
+
+    self$root_path <- root
+    self$year <- match.arg(year, choices = unique(self$resources$year))
+    self$split <- match.arg(split, choices = c("train", "val", "trainval", "test"))
+    self$transform <- transform
+    self$target_transform <- target_transform
+    if (self$split == "test") {
+      self$archive_key <- "test"
+    } else {
+      self$archive_key <- "trainval"
+    }
+    self$archive_size <- self$resources[self$resources$year == self$year & self$resources$type == self$archive_key,]$size
+
+    if (download) {
+      cli_inform("Dataset {.cls {class(self)[[1]]}} (~{.emph {self$archive_size}}) will be downloaded and processed if not already available.")
+      self$download()
+    }
+
+    if (!self$check_exists()) {
+      cli_abort("Dataset not found. You can use `download = TRUE` to download it.")
+    }
+
+    voc_dir <- file.path(self$raw_folder, "VOCdevkit", paste0("VOC", self$year))
+    if (self$year == "2011") {
+      voc_dir <- file.path(self$raw_folder, "TrainVal", "VOCdevkit", paste0("VOC", self$year))
+    }
+
+    ids_file <- file.path(voc_dir, "ImageSets", "Main", paste0(self$split, ".txt"))
+    ids <- readLines(ids_file)
+
+    self$img_path <- file.path(voc_dir, "JPEGImages", paste0(ids, ".jpg"))
+    self$annotation_paths <- file.path(voc_dir, "Annotations", paste0(ids, ".xml"))
+
+    if (!requireNamespace("xml2", quietly = TRUE)) {
+      install.packages("xml2")
+    }
+
+    cli_inform("{.cls {class(self)[[1]]}} dataset loaded with {length(self$img_path)} images across {length(self$classes)} classes.")
+  },
+
+  .getitem = function(index) {
+
+    x <- jpeg::readJPEG(self$img_path[index])
+    ann_path <- self$annotation_paths[index]
+    y <- self$parse_voc_xml(xml2::read_xml(ann_path))
+
+    if (!is.null(self$transform)) {
+      x <- self$transform(x)
+    }
+    if (!is.null(self$target_transform)) {
+      y <- self$target_transform(y)
+    }
+
+    structure(list(x = x, y = y), class = "image_with_bounding_box")
+  },
+
+  parse_voc_xml = function(xml) {
+    objects <- xml2::xml_find_all(xml, ".//object")
+
+    labels <- xml2::xml_text(xml2::xml_find_all(objects, "name"))
+
+    bboxes <- xml2::xml_find_all(objects, "bndbox")
+
+    xmin <- xml2::xml_integer(xml2::xml_find_all(bboxes, "xmin"))
+    ymin <- xml2::xml_integer(xml2::xml_find_all(bboxes, "ymin"))
+    xmax <- xml2::xml_integer(xml2::xml_find_all(bboxes, "xmax"))
+    ymax <- xml2::xml_integer(xml2::xml_find_all(bboxes, "ymax"))
+
+    boxes <- torch_tensor(data.frame(xmin, ymin, xmax, ymax) %>% as.matrix(), dtype = torch_long())
+
+    list(
+      labels = labels,
+      boxes = boxes
+    )
+  }
+)