add utils for visualization.

Summary:
Pull Request resolved: #179

add utils for visualization.
* able to draw images with labels as a grid, preserving the resolutions of the input images.

Reviewed By: zechenghe

Differential Revision: D48223608

fbshipit-source-id: 0b5d20c2357755ef420f94e606fbe7636c2461d5

mobile_cv/common/misc/visualize_utils.py

@@ -0,0 +1,247 @@
+import math
+import os
+from typing import Any, Dict, List, Optional
+
+from mobile_cv.common.misc.oss_utils import fb_overwritable
+
+from PIL import Image, ImageDraw, ImageFont
+
+
+@fb_overwritable()
+def get_font_path() -> Optional[str]:
+    return None
+
+
+def save_as_image_grids(
+    rows: List[Dict[str, Any]],
+    output_dir: str,
+    path_manager,
+    max_rows_per_image: Optional[int] = None,
+    grid_padding_rows: int = 15,
+    grid_padding_cols: int = 10,
+    font_size: int = 10,
+) -> List[str]:
+    """
+    Draw and save image grids, preserve the image sizes.
+    rows: List of dicts that represent each row in the grid. Each dict must have
+        the keys "images", and optional keys "row_title", "titles", and "labels":
+        * images (List[str]): List of image paths for the row,
+        * row_title (Optional[str]): The title of the row
+        * titles (Optional[List[str]]): List of titles for each image in the row,
+            drawing on top of each image
+        * labels (Optional[List[str]]): List of labels for each image in the row,
+            drawing under each image
+    output_dir: output folder of the saved images, image will be saved with file
+        names "grid_{start_row_idx}.png"
+    path_manager: path manager for io
+    max_rows_per_image: maximum number of rows per image, multiple images could
+        be generated.
+    grid_padding_rows: Number of pixels between each row in the grid
+    grid_padding_cols: Number of pixels between each column in the grid
+    font_size: Size of font
+    """
+    if not path_manager.exists(output_dir):
+        path_manager.mkdirs(output_dir)
+
+    if max_rows_per_image is None:
+        max_rows_per_image = len(rows)
+
+    ret = []
+    start_row = 0
+    while start_row < len(rows):
+        end_row = min(len(rows), (start_row + max_rows_per_image))
+        grid_img = draw_image_grid_by_rows(
+            path_manager,
+            rows[start_row:end_row],
+            grid_padding_rows=grid_padding_rows,
+            grid_padding_cols=grid_padding_cols,
+            font_size=font_size,
+        )
+
+        output_filepath = os.path.join(output_dir, f"grid_{start_row:05d}.png")
+        with path_manager.open(output_filepath, "wb") as fp:
+            grid_img.save(fp)
+        start_row = end_row
+        ret.append(output_filepath)
+
+    return ret
+
+
+def draw_image_grid_by_rows(
+    path_manager,
+    rows: List[Dict[str, Any]],
+    grid_padding_rows: int = 15,
+    grid_padding_cols: int = 10,
+    font_size: int = 10,
+) -> Image.Image:
+    """
+    Draw a grid of images into a single image, preserve the image sizes.
+    rows: List of dicts that represent each row in the grid. Each dict must have
+        the keys "images", and optional keys "row_title", "titles", and "labels":
+        * images (List[str]): List of image paths for the row,
+        * row_title (Optional[str]): The title of the row
+        * titles (Optional[List[str]]): List of titles for each image in the row,
+            drawing on top of each image
+        * labels (Optional[List[str]]): List of labels for each image in the row,
+            drawing under each image
+    grid_padding_rows: Number of pixels between each row in the grid
+    grid_padding_cols: Number of pixels between each column in the grid
+    font_size: Size of font
+    """
+    image_paths = []
+    columns: Optional[int] = None
+    row_titles = []
+    image_titles = []
+    image_labels = []
+    for item in rows:
+        # images
+        images = item["images"]
+        assert isinstance(images, list)
+        if columns is None:
+            columns = len(images)
+        else:
+            assert len(images) == columns
+        image_paths.extend(images)
+
+        # row title
+        row_title = item.get("row_title", None)
+        row_titles.append(row_title)
+
+        # image_titles
+        image_title = item.get("titles", None)
+        if image_title is not None:
+            assert isinstance(image_title, list) and len(image_title) == columns
+            image_titles.extend(image_title)
+        else:
+            image_titles.extend([None] * columns)
+
+        # image_labels
+        image_label = item.get("labels", None)
+        if image_label is not None:
+            assert isinstance(image_label, list) and len(image_label) == columns
+            image_labels.extend(image_label)
+        else:
+            image_labels.extend([None] * columns)
+
+    return draw_image_grid(
+        path_manager,
+        image_paths,
+        columns=columns,
+        row_titles=row_titles,
+        image_titles=image_titles,
+        image_labels=image_labels,
+        grid_padding_rows=grid_padding_rows,
+        grid_padding_cols=grid_padding_cols,
+        font_size=font_size,
+    )
+
+
+def draw_image_grid(
+    path_manager,
+    image_paths: List[str],
+    columns: int,
+    row_titles: Optional[List[str]] = None,
+    image_titles: Optional[List[str]] = None,
+    image_labels: Optional[List[str]] = None,
+    grid_padding_rows: int = 15,
+    grid_padding_cols: int = 10,
+    font_size: int = 10,
+) -> Image.Image:
+    """
+    Draw a grid of images into a single image, preserve the image sizes.
+    image_paths: List of images paths
+    columns: number of columns in the grid
+    """
+
+    num_images = len(image_paths)
+    rows = math.ceil(num_images / columns)
+
+    if row_titles is not None:
+        assert len(row_titles) == rows, f"{len(row_titles), rows}"
+    if image_titles is not None:
+        assert len(image_titles) == num_images, f"{len(image_titles), num_images}"
+    if image_labels is not None:
+        assert len(image_labels) == num_images, f"{len(image_labels), num_images}"
+
+    # Load the images from file paths
+    images = []
+    for ip in image_paths:
+        with path_manager.open(ip, "rb") as fp:
+            images.append(Image.open(fp))
+            images[-1].load()
+
+    # Calculate grid dimensions
+    grid_width = columns * (max(image.width for image in images) + grid_padding_cols)
+    grid_height = rows * (max(image.height for image in images) + grid_padding_rows * 3)
+
+    # Create a blank canvas for the grid
+    grid_image = Image.new("RGB", (grid_width, grid_height), color="white")
+    draw = ImageDraw.Draw(grid_image)
+
+    # # Load fonts
+    font_path = get_font_path()
+    if font_path is not None:
+        font_path = path_manager.get_local_path(font_path)
+        title_font = ImageFont.truetype(font_path, font_size)
+        label_font = ImageFont.truetype(font_path, font_size)
+    else:
+        title_font = ImageFont.load_default()
+        label_font = ImageFont.load_default()
+
+    # Draw the images and labels on the grid
+    for row in range(rows):
+        # Calculate starting position for the current row
+        start_x = 0
+        start_y = row * (max(image.height for image in images) + grid_padding_rows * 3)
+
+        # Draw the title for the current row
+        if row_titles is not None:
+            draw.text(
+                (start_x, start_y), row_titles[row], font=title_font, fill="black"
+            )
+
+        # Draw the images and labels for the current row
+        for col in range(columns):
+            # Calculate the position for the current image and label
+            image_index = row * columns + col
+            if image_index >= num_images:
+                break
+
+            image = images[image_index]
+            label = image_labels[image_index] if image_labels is not None else None
+            image_title = (
+                image_titles[image_index] if image_titles is not None else None
+            )
+
+            image_x = start_x + col * (image.width + grid_padding_cols)
+            image_y = start_y + grid_padding_rows * 2
+
+            # Paste the image onto the grid
+            grid_image.paste(image, (image_x, image_y))
+
+            # Draw the label below the image
+            if label is not None:
+                label_width, label_height = label_font.getsize(label)
+                label_x = (
+                    image_x + (image.width - label_width) // 2
+                )  # Center horizontally
+                label_y = image_y + image.height
+
+                draw.text((label_x, label_y), label, font=label_font, fill="black")
+
+            # Draw the image title above the image
+            if image_title is not None:
+                image_title_width, image_title_height = title_font.getsize(image_title)
+                image_title_x = (
+                    image_x + (image.width - image_title_width) // 2
+                )  # Center horizontally
+                image_title_y = start_y + grid_padding_rows
+
+                draw.text(
+                    (image_title_x, image_title_y),
+                    image_title,
+                    font=title_font,
+                    fill="black",
+                )
+
+    return grid_image