draw_box_utils.py

import collections
import PIL.ImageDraw as ImageDraw
import PIL.ImageFont as ImageFont
import numpy as np

STANDARD_COLORS = [
    'AliceBlue', 'Chartreuse', 'Aqua', 'Aquamarine', 'Azure', 'Beige', 'Bisque',
    'BlanchedAlmond', 'BlueViolet', 'BurlyWood', 'CadetBlue', 'AntiqueWhite',
    'Chocolate', 'Coral', 'CornflowerBlue', 'Cornsilk', 'Crimson', 'Cyan',
    'DarkCyan', 'DarkGoldenRod', 'DarkGrey', 'DarkKhaki', 'DarkOrange',
    'DarkOrchid', 'DarkSalmon', 'DarkSeaGreen', 'DarkTurquoise', 'DarkViolet',
    'DeepPink', 'DeepSkyBlue', 'DodgerBlue', 'FireBrick', 'FloralWhite',
    'ForestGreen', 'Fuchsia', 'Gainsboro', 'GhostWhite', 'Gold', 'GoldenRod',
    'Salmon', 'Tan', 'HoneyDew', 'HotPink', 'IndianRed', 'Ivory', 'Khaki',
    'Lavender', 'LavenderBlush', 'LawnGreen', 'LemonChiffon', 'LightBlue',
    'LightCoral', 'LightCyan', 'LightGoldenRodYellow', 'LightGray', 'LightGrey',
    'LightGreen', 'LightPink', 'LightSalmon', 'LightSeaGreen', 'LightSkyBlue',
    'LightSlateGray', 'LightSlateGrey', 'LightSteelBlue', 'LightYellow', 'Lime',
    'LimeGreen', 'Linen', 'Magenta', 'MediumAquaMarine', 'MediumOrchid',
    'MediumPurple', 'MediumSeaGreen', 'MediumSlateBlue', 'MediumSpringGreen',
    'MediumTurquoise', 'MediumVioletRed', 'MintCream', 'MistyRose', 'Moccasin',
    'NavajoWhite', 'OldLace', 'Olive', 'OliveDrab', 'Orange', 'OrangeRed',
    'Orchid', 'PaleGoldenRod', 'PaleGreen', 'PaleTurquoise', 'PaleVioletRed',
    'PapayaWhip', 'PeachPuff', 'Peru', 'Pink', 'Plum', 'PowderBlue', 'Purple',
    'Red', 'RosyBrown', 'RoyalBlue', 'SaddleBrown', 'Green', 'SandyBrown',
    'SeaGreen', 'SeaShell', 'Sienna', 'Silver', 'SkyBlue', 'SlateBlue',
    'SlateGray', 'SlateGrey', 'Snow', 'SpringGreen', 'SteelBlue', 'GreenYellow',
    'Teal', 'Thistle', 'Tomato', 'Turquoise', 'Violet', 'Wheat', 'White',
    'WhiteSmoke', 'Yellow', 'YellowGreen'
]


def filter_low_thresh(boxes, scores, classes, category_index, thresh, box_to_display_str_map, box_to_color_map):
    for i in range(boxes.shape[0]):
        if scores[i] > thresh:
            box = tuple(boxes[i].tolist())  # numpy -> list -> tuple
            if classes[i] in category_index.keys():
                class_name = category_index[classes[i]]
            else:
                class_name = 'N/A'
            display_str = str(class_name)
            display_str = '{}: {}%'.format(display_str, int(100 * scores[i]))
            box_to_display_str_map[box].append(display_str)
            box_to_color_map[box] = STANDARD_COLORS[
                classes[i] % len(STANDARD_COLORS)]
        else:
            break


def draw_text(draw, box_to_display_str_map, box, left, right, top, bottom, color):
    try:
        font = ImageFont.truetype('arial.ttf', 12)
    except IOError:
        font = ImageFont.load_default()

    # If the total height of the display strings added to the top of the bounding
    # box exceeds the top of the image, stack the strings below the bounding box
    # instead of above.
    display_str_heights = [font.getsize(ds)[1] for ds in box_to_display_str_map[box]]
    # Each display_str has a top and bottom margin of 0.05x.
    total_display_str_height = (1 + 2 * 0.05) * sum(display_str_heights)

    if top > total_display_str_height:
        text_bottom = top
    else:
        text_bottom = bottom + total_display_str_height
    # Reverse list and print from bottom to top.
    for display_str in box_to_display_str_map[box][::-1]:
        text_width, text_height = font.getsize(display_str)
        margin = np.ceil(0.05 * text_height)
        draw.rectangle([(left, text_bottom - text_height - 2 * margin),
                        (left + text_width, text_bottom)], fill=color)
        draw.text((left + margin, text_bottom - text_height - margin),
                  display_str,
                  fill='black',
                  font=font)
        text_bottom -= text_height - 2 * margin


def draw_box(image, boxes, classes, scores, category_index, thresh=0.5, line_thickness=8):
    box_to_display_str_map = collections.defaultdict(list)
    box_to_color_map = collections.defaultdict(str)

    filter_low_thresh(boxes, scores, classes, category_index, thresh, box_to_display_str_map, box_to_color_map)

    # Draw all boxes onto image.
    draw = ImageDraw.Draw(image)
    im_width, im_height = image.size
    for box, color in box_to_color_map.items():
        xmin, ymin, xmax, ymax = box
        (left, right, top, bottom) = (xmin * 1, xmax * 1,
                                      ymin * 1, ymax * 1)
        draw.line([(left, top), (left, bottom), (right, bottom),
                   (right, top), (left, top)], width=line_thickness, fill=color)
        draw_text(draw, box_to_display_str_map, box, left, right, top, bottom, color)