def chapter_examples_bounding_boxes_iou():
import numpy as np
import imgaug as ia
from imgaug.augmentables.bbs import BoundingBox
ia.seed(1)
# Define image with two bounding boxes.
image = ia.quokka(size=(256, 256))
bb1 = BoundingBox(x1=50, x2=100, y1=25, y2=75)
bb2 = BoundingBox(x1=75, x2=125, y1=50, y2=100)
# Compute intersection, union and IoU value
# Intersection and union are both bounding boxes. They are here
# decreased/increased in size purely for better visualization.
bb_inters = bb1.intersection(bb2).extend(all_sides=-1)
bb_union = bb1.union(bb2).extend(all_sides=2)
iou = bb1.iou(bb2)
# Draw bounding boxes, intersection, union and IoU value on image.
image_bbs = np.copy(image)
image_bbs = bb1.draw_on_image(image_bbs, size=2, color=[0, 255, 0])
image_bbs = bb2.draw_on_image(image_bbs, size=2, color=[0, 255, 0])
image_bbs = bb_inters.draw_on_image(image_bbs, size=2, color=[255, 0, 0])
image_bbs = bb_union.draw_on_image(image_bbs, size=2, color=[0, 0, 255])
image_bbs = ia.draw_text(image_bbs,
text="IoU=%.2f" % (iou, ),
x=bb_union.x2 + 10,
y=bb_union.y1 + bb_union.height // 2,
color=[255, 255, 255],
size=13)
# ------------
save("examples_bounding_boxes",
"iou.jpg",
grid([image_bbs], cols=1, rows=1),
quality=90)
BoundingBox(x1=100, x2=150, y1=25, y2=75),
BoundingBox(x1=175, x2=225, y1=25, y2=75)
],
shape=image.shape)
seq = iaa.Affine(translate_px={"x": 120})
image_aug, bbs_aug = seq(image=image, bounding_boxes=bbs)
# Draw the BBs (a) in their original form, (b) after augmentation,
# (c) after augmentation and removing those fully outside the image,
# (d) after augmentation and removing those fully outside the image and
# clipping those partially inside the image so that they are fully inside.
image_before = draw_bbs(image, bbs, 100)
image_after1 = draw_bbs(image_aug, bbs_aug, 100)
image_after2 = draw_bbs(image_aug, bbs_aug.remove_out_of_image(), 100)
image_after3 = draw_bbs(image_aug,
bbs_aug.remove_out_of_image().clip_out_of_image(), 100)
ia.imshow(image_after2)
[x.compute_out_of_image_fraction(image) for x in bbs_aug]
ia.imshow(image_after3)
# compute iou
bb1 = BoundingBox(x1=50, x2=100, y1=25, y2=75)
bb2 = BoundingBox(x1=75, x2=125, y1=50, y2=100)
# Compute intersection, union and IoU value
# Intersection and union are both bounding boxes. They are here
# decreased/increased in size purely for better visualization.
bb_inters = bb1.intersection(bb2).extend(all_sides=-1)
bb_union = bb1.union(bb2).extend(all_sides=2)
iou = bb1.iou(bb2)