.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/plot_visualization_utils.py"
.. LINE NUMBERS ARE GIVEN BELOW.
.. only:: html
.. note::
:class: sphx-glr-download-link-note
:ref:`Go to the end <sphx_glr_download_auto_examples_plot_visualization_utils.py>`
to download the full example code
.. rst-class:: sphx-glr-example-title
.. _sphx_glr_auto_examples_plot_visualization_utils.py:
=======================
Visualization utilities
=======================
This example illustrates some of the utilities that torchvision offers for
visualizing images, bounding boxes, segmentation masks and keypoints.
.. GENERATED FROM PYTHON SOURCE LINES 9-32
.. code-block:: default
import torch
import numpy as np
import matplotlib.pyplot as plt
import torchvision.transforms.functional as F
plt.rcParams["savefig.bbox"] = 'tight'
def show(imgs):
if not isinstance(imgs, list):
imgs = [imgs]
fig, axs = plt.subplots(ncols=len(imgs), squeeze=False)
for i, img in enumerate(imgs):
img = img.detach()
img = F.to_pil_image(img)
axs[0, i].imshow(np.asarray(img))
axs[0, i].set(xticklabels=[], yticklabels=[], xticks=[], yticks=[])
.. GENERATED FROM PYTHON SOURCE LINES 34-39
Visualizing a grid of images
----------------------------
The :func:`~torchvision.utils.make_grid` function can be used to create a
tensor that represents multiple images in a grid. This util requires a single
image of dtype ``uint8`` as input.
.. GENERATED FROM PYTHON SOURCE LINES 39-51
.. code-block:: default
from torchvision.utils import make_grid
from torchvision.io import read_image
from pathlib import Path
dog1_int = read_image(str(Path('assets') / 'dog1.jpg'))
dog2_int = read_image(str(Path('assets') / 'dog2.jpg'))
dog_list = [dog1_int, dog2_int]
grid = make_grid(dog_list)
show(grid)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_001.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_001.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 52-57
Visualizing bounding boxes
--------------------------
We can use :func:`~torchvision.utils.draw_bounding_boxes` to draw boxes on an
image. We can set the colors, labels, width as well as font and font size.
The boxes are in ``(xmin, ymin, xmax, ymax)`` format.
.. GENERATED FROM PYTHON SOURCE LINES 57-67
.. code-block:: default
from torchvision.utils import draw_bounding_boxes
boxes = torch.tensor([[50, 50, 100, 200], [210, 150, 350, 430]], dtype=torch.float)
colors = ["blue", "yellow"]
result = draw_bounding_boxes(dog1_int, boxes, colors=colors, width=5)
show(result)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_002.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_002.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 68-73
Naturally, we can also plot bounding boxes produced by torchvision detection
models. Here is a demo with a Faster R-CNN model loaded from
:func:`~torchvision.models.detection.fasterrcnn_resnet50_fpn`
model. For more details on the output of such models, you may
refer to :ref:`instance_seg_output`.
.. GENERATED FROM PYTHON SOURCE LINES 73-88
.. code-block:: default
from torchvision.models.detection import fasterrcnn_resnet50_fpn, FasterRCNN_ResNet50_FPN_Weights
weights = FasterRCNN_ResNet50_FPN_Weights.DEFAULT
transforms = weights.transforms()
images = [transforms(d) for d in dog_list]
model = fasterrcnn_resnet50_fpn(weights=weights, progress=False)
model = model.eval()
outputs = model(images)
print(outputs)
.. rst-class:: sphx-glr-script-out
.. code-block:: none
[{'boxes': tensor([[215.9767, 171.1661, 402.0078, 378.7391],
[344.6341, 172.6735, 357.6114, 220.1435],
[153.1306, 185.5568, 172.9223, 254.7014]], grad_fn=<StackBackward0>), 'labels': tensor([18, 1, 1]), 'scores': tensor([0.9989, 0.0701, 0.0611], grad_fn=<IndexBackward0>)}, {'boxes': tensor([[ 23.5963, 132.4332, 449.9359, 493.0222],
[225.8183, 124.6292, 467.2861, 492.2621],
[ 18.5249, 135.4171, 420.9786, 479.2226]], grad_fn=<StackBackward0>), 'labels': tensor([18, 18, 17]), 'scores': tensor([0.9980, 0.0879, 0.0671], grad_fn=<IndexBackward0>)}]
.. GENERATED FROM PYTHON SOURCE LINES 89-91
Let's plot the boxes detected by our model. We will only plot the boxes with a
score greater than a given threshold.
.. GENERATED FROM PYTHON SOURCE LINES 91-99
.. code-block:: default
score_threshold = .8
dogs_with_boxes = [
draw_bounding_boxes(dog_int, boxes=output['boxes'][output['scores'] > score_threshold], width=4)
for dog_int, output in zip(dog_list, outputs)
]
show(dogs_with_boxes)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_003.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_003.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 100-115
Visualizing segmentation masks
------------------------------
The :func:`~torchvision.utils.draw_segmentation_masks` function can be used to
draw segmentation masks on images. Semantic segmentation and instance
segmentation models have different outputs, so we will treat each
independently.
.. _semantic_seg_output:
Semantic segmentation models
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
We will see how to use it with torchvision's FCN Resnet-50, loaded with
:func:`~torchvision.models.segmentation.fcn_resnet50`. Let's start by looking
at the output of the model.
.. GENERATED FROM PYTHON SOURCE LINES 115-128
.. code-block:: default
from torchvision.models.segmentation import fcn_resnet50, FCN_ResNet50_Weights
weights = FCN_ResNet50_Weights.DEFAULT
transforms = weights.transforms(resize_size=None)
model = fcn_resnet50(weights=weights, progress=False)
model = model.eval()
batch = torch.stack([transforms(d) for d in dog_list])
output = model(batch)['out']
print(output.shape, output.min().item(), output.max().item())
.. rst-class:: sphx-glr-script-out
.. code-block:: none
torch.Size([2, 21, 500, 500]) -7.089669704437256 14.858256340026855
.. GENERATED FROM PYTHON SOURCE LINES 129-137
As we can see above, the output of the segmentation model is a tensor of shape
``(batch_size, num_classes, H, W)``. Each value is a non-normalized score, and
we can normalize them into ``[0, 1]`` by using a softmax. After the softmax,
we can interpret each value as a probability indicating how likely a given
pixel is to belong to a given class.
Let's plot the masks that have been detected for the dog class and for the
boat class:
.. GENERATED FROM PYTHON SOURCE LINES 137-150
.. code-block:: default
sem_class_to_idx = {cls: idx for (idx, cls) in enumerate(weights.meta["categories"])}
normalized_masks = torch.nn.functional.softmax(output, dim=1)
dog_and_boat_masks = [
normalized_masks[img_idx, sem_class_to_idx[cls]]
for img_idx in range(len(dog_list))
for cls in ('dog', 'boat')
]
show(dog_and_boat_masks)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_004.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_004.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 151-158
As expected, the model is confident about the dog class, but not so much for
the boat class.
The :func:`~torchvision.utils.draw_segmentation_masks` function can be used to
plots those masks on top of the original image. This function expects the
masks to be boolean masks, but our masks above contain probabilities in ``[0,
1]``. To get boolean masks, we can do the following:
.. GENERATED FROM PYTHON SOURCE LINES 158-165
.. code-block:: default
class_dim = 1
boolean_dog_masks = (normalized_masks.argmax(class_dim) == sem_class_to_idx['dog'])
print(f"shape = {boolean_dog_masks.shape}, dtype = {boolean_dog_masks.dtype}")
show([m.float() for m in boolean_dog_masks])
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_005.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_005.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
.. code-block:: none
shape = torch.Size([2, 500, 500]), dtype = torch.bool
.. GENERATED FROM PYTHON SOURCE LINES 166-178
The line above where we define ``boolean_dog_masks`` is a bit cryptic, but you
can read it as the following query: "For which pixels is 'dog' the most likely
class?"
.. note::
While we're using the ``normalized_masks`` here, we would have
gotten the same result by using the non-normalized scores of the model
directly (as the softmax operation preserves the order).
Now that we have boolean masks, we can use them with
:func:`~torchvision.utils.draw_segmentation_masks` to plot them on top of the
original images:
.. GENERATED FROM PYTHON SOURCE LINES 178-187
.. code-block:: default
from torchvision.utils import draw_segmentation_masks
dogs_with_masks = [
draw_segmentation_masks(img, masks=mask, alpha=0.7)
for img, mask in zip(dog_list, boolean_dog_masks)
]
show(dogs_with_masks)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_006.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_006.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 188-195
We can plot more than one mask per image! Remember that the model returned as
many masks as there are classes. Let's ask the same query as above, but this
time for *all* classes, not just the dog class: "For each pixel and each class
C, is class C the most likely class?"
This one is a bit more involved, so we'll first show how to do it with a
single image, and then we'll generalize to the batch
.. GENERATED FROM PYTHON SOURCE LINES 195-207
.. code-block:: default
num_classes = normalized_masks.shape[1]
dog1_masks = normalized_masks[0]
class_dim = 0
dog1_all_classes_masks = dog1_masks.argmax(class_dim) == torch.arange(num_classes)[:, None, None]
print(f"dog1_masks shape = {dog1_masks.shape}, dtype = {dog1_masks.dtype}")
print(f"dog1_all_classes_masks = {dog1_all_classes_masks.shape}, dtype = {dog1_all_classes_masks.dtype}")
dog_with_all_masks = draw_segmentation_masks(dog1_int, masks=dog1_all_classes_masks, alpha=.6)
show(dog_with_all_masks)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_007.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_007.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
.. code-block:: none
dog1_masks shape = torch.Size([21, 500, 500]), dtype = torch.float32
dog1_all_classes_masks = torch.Size([21, 500, 500]), dtype = torch.bool
.. GENERATED FROM PYTHON SOURCE LINES 208-220
We can see in the image above that only 2 masks were drawn: the mask for the
background and the mask for the dog. This is because the model thinks that
only these 2 classes are the most likely ones across all the pixels. If the
model had detected another class as the most likely among other pixels, we
would have seen its mask above.
Removing the background mask is as simple as passing
``masks=dog1_all_classes_masks[1:]``, because the background class is the
class with index 0.
Let's now do the same but for an entire batch of images. The code is similar
but involves a bit more juggling with the dimensions.
.. GENERATED FROM PYTHON SOURCE LINES 220-234
.. code-block:: default
class_dim = 1
all_classes_masks = normalized_masks.argmax(class_dim) == torch.arange(num_classes)[:, None, None, None]
print(f"shape = {all_classes_masks.shape}, dtype = {all_classes_masks.dtype}")
# The first dimension is the classes now, so we need to swap it
all_classes_masks = all_classes_masks.swapaxes(0, 1)
dogs_with_masks = [
draw_segmentation_masks(img, masks=mask, alpha=.6)
for img, mask in zip(dog_list, all_classes_masks)
]
show(dogs_with_masks)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_008.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_008.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
.. code-block:: none
shape = torch.Size([21, 2, 500, 500]), dtype = torch.bool
.. GENERATED FROM PYTHON SOURCE LINES 235-254
.. _instance_seg_output:
Instance segmentation models
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Instance segmentation models have a significantly different output from the
semantic segmentation models. We will see here how to plot the masks for such
models. Let's start by analyzing the output of a Mask-RCNN model. Note that
these models don't require the images to be normalized, so we don't need to
use the normalized batch.
.. note::
We will here describe the output of a Mask-RCNN model. The models in
:ref:`object_det_inst_seg_pers_keypoint_det` all have a similar output
format, but some of them may have extra info like keypoints for
:func:`~torchvision.models.detection.keypointrcnn_resnet50_fpn`, and some
of them may not have masks, like
:func:`~torchvision.models.detection.fasterrcnn_resnet50_fpn`.
.. GENERATED FROM PYTHON SOURCE LINES 254-268
.. code-block:: default
from torchvision.models.detection import maskrcnn_resnet50_fpn, MaskRCNN_ResNet50_FPN_Weights
weights = MaskRCNN_ResNet50_FPN_Weights.DEFAULT
transforms = weights.transforms()
images = [transforms(d) for d in dog_list]
model = maskrcnn_resnet50_fpn(weights=weights, progress=False)
model = model.eval()
output = model(images)
print(output)
.. rst-class:: sphx-glr-script-out
.. code-block:: none
[{'boxes': tensor([[219.7444, 168.1722, 400.7379, 384.0263],
[343.9716, 171.2287, 358.3447, 222.6263],
[301.0303, 192.6917, 313.8879, 232.3154]], grad_fn=<StackBackward0>), 'labels': tensor([18, 1, 1]), 'scores': tensor([0.9987, 0.7187, 0.6525], grad_fn=<IndexBackward0>), 'masks': tensor([[[[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
...,
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.]]],
[[[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
...,
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.]]],
[[[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
...,
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.]]]], grad_fn=<UnsqueezeBackward0>)}, {'boxes': tensor([[ 44.6767, 137.9018, 446.5324, 487.3429],
[ 0.0000, 288.0053, 489.9293, 490.2352]], grad_fn=<StackBackward0>), 'labels': tensor([18, 15]), 'scores': tensor([0.9978, 0.0697], grad_fn=<IndexBackward0>), 'masks': tensor([[[[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
...,
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.]]],
[[[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
...,
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.],
[0., 0., 0., ..., 0., 0., 0.]]]], grad_fn=<UnsqueezeBackward0>)}]
.. GENERATED FROM PYTHON SOURCE LINES 269-285
Let's break this down. For each image in the batch, the model outputs some
detections (or instances). The number of detections varies for each input
image. Each instance is described by its bounding box, its label, its score
and its mask.
The way the output is organized is as follows: the output is a list of length
``batch_size``. Each entry in the list corresponds to an input image, and it
is a dict with keys 'boxes', 'labels', 'scores', and 'masks'. Each value
associated to those keys has ``num_instances`` elements in it. In our case
above there are 3 instances detected in the first image, and 2 instances in
the second one.
The boxes can be plotted with :func:`~torchvision.utils.draw_bounding_boxes`
as above, but here we're more interested in the masks. These masks are quite
different from the masks that we saw above for the semantic segmentation
models.
.. GENERATED FROM PYTHON SOURCE LINES 285-291
.. code-block:: default
dog1_output = output[0]
dog1_masks = dog1_output['masks']
print(f"shape = {dog1_masks.shape}, dtype = {dog1_masks.dtype}, "
f"min = {dog1_masks.min()}, max = {dog1_masks.max()}")
.. rst-class:: sphx-glr-script-out
.. code-block:: none
shape = torch.Size([3, 1, 500, 500]), dtype = torch.float32, min = 0.0, max = 0.9999862909317017
.. GENERATED FROM PYTHON SOURCE LINES 292-296
Here the masks correspond to probabilities indicating, for each pixel, how
likely it is to belong to the predicted label of that instance. Those
predicted labels correspond to the 'labels' element in the same output dict.
Let's see which labels were predicted for the instances of the first image.
.. GENERATED FROM PYTHON SOURCE LINES 296-300
.. code-block:: default
print("For the first dog, the following instances were detected:")
print([weights.meta["categories"][label] for label in dog1_output['labels']])
.. rst-class:: sphx-glr-script-out
.. code-block:: none
For the first dog, the following instances were detected:
['dog', 'person', 'person']
.. GENERATED FROM PYTHON SOURCE LINES 301-308
Interestingly, the model detects two persons in the image. Let's go ahead and
plot those masks. Since :func:`~torchvision.utils.draw_segmentation_masks`
expects boolean masks, we need to convert those probabilities into boolean
values. Remember that the semantic of those masks is "How likely is this pixel
to belong to the predicted class?". As a result, a natural way of converting
those masks into boolean values is to threshold them with the 0.5 probability
(one could also choose a different threshold).
.. GENERATED FROM PYTHON SOURCE LINES 308-318
.. code-block:: default
proba_threshold = 0.5
dog1_bool_masks = dog1_output['masks'] > proba_threshold
print(f"shape = {dog1_bool_masks.shape}, dtype = {dog1_bool_masks.dtype}")
# There's an extra dimension (1) to the masks. We need to remove it
dog1_bool_masks = dog1_bool_masks.squeeze(1)
show(draw_segmentation_masks(dog1_int, dog1_bool_masks, alpha=0.9))
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_009.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_009.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
.. code-block:: none
shape = torch.Size([3, 1, 500, 500]), dtype = torch.bool
.. GENERATED FROM PYTHON SOURCE LINES 319-322
The model seems to have properly detected the dog, but it also confused trees
with people. Looking more closely at the scores will help us plot more
relevant masks:
.. GENERATED FROM PYTHON SOURCE LINES 322-325
.. code-block:: default
print(dog1_output['scores'])
.. rst-class:: sphx-glr-script-out
.. code-block:: none
tensor([0.9987, 0.7187, 0.6525], grad_fn=<IndexBackward0>)
.. GENERATED FROM PYTHON SOURCE LINES 326-330
Clearly the model is more confident about the dog detection than it is about
the people detections. That's good news. When plotting the masks, we can ask
for only those that have a good score. Let's use a score threshold of .75
here, and also plot the masks of the second dog.
.. GENERATED FROM PYTHON SOURCE LINES 330-344
.. code-block:: default
score_threshold = .75
boolean_masks = [
out['masks'][out['scores'] > score_threshold] > proba_threshold
for out in output
]
dogs_with_masks = [
draw_segmentation_masks(img, mask.squeeze(1))
for img, mask in zip(dog_list, boolean_masks)
]
show(dogs_with_masks)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_010.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_010.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 345-348
The two 'people' masks in the first image where not selected because they have
a lower score than the score threshold. Similarly, in the second image, the
instance with class 15 (which corresponds to 'bench') was not selected.
.. GENERATED FROM PYTHON SOURCE LINES 350-359
.. _keypoint_output:
Visualizing keypoints
------------------------------
The :func:`~torchvision.utils.draw_keypoints` function can be used to
draw keypoints on images. We will see how to use it with
torchvision's KeypointRCNN loaded with :func:`~torchvision.models.detection.keypointrcnn_resnet50_fpn`.
We will first have a look at output of the model.
.. GENERATED FROM PYTHON SOURCE LINES 359-376
.. code-block:: default
from torchvision.models.detection import keypointrcnn_resnet50_fpn, KeypointRCNN_ResNet50_FPN_Weights
from torchvision.io import read_image
person_int = read_image(str(Path("assets") / "person1.jpg"))
weights = KeypointRCNN_ResNet50_FPN_Weights.DEFAULT
transforms = weights.transforms()
person_float = transforms(person_int)
model = keypointrcnn_resnet50_fpn(weights=weights, progress=False)
model = model.eval()
outputs = model([person_float])
print(outputs)
.. rst-class:: sphx-glr-script-out
.. code-block:: none
[{'boxes': tensor([[124.3751, 177.9242, 327.6353, 574.7064],
[124.3625, 180.7574, 290.1061, 390.7958]], grad_fn=<StackBackward0>), 'labels': tensor([1, 1]), 'scores': tensor([0.9998, 0.1070], grad_fn=<IndexBackward0>), 'keypoints': tensor([[[208.0176, 214.2408, 1.0000],
[208.0176, 207.0375, 1.0000],
[197.8246, 210.6392, 1.0000],
[208.0176, 211.8398, 1.0000],
[178.6378, 217.8425, 1.0000],
[221.2085, 253.8590, 1.0000],
[160.6502, 269.4662, 1.0000],
[243.9929, 304.2822, 1.0000],
[138.4654, 328.8935, 1.0000],
[277.5698, 340.8990, 1.0000],
[153.4551, 374.5144, 1.0000],
[226.0052, 375.7150, 1.0000],
[226.0052, 370.3125, 1.0000],
[221.8081, 455.5516, 1.0000],
[273.9723, 448.9486, 1.0000],
[193.6275, 546.1932, 1.0000],
[273.3727, 545.5930, 1.0000]],
[[207.8327, 214.6636, 1.0000],
[207.2343, 207.4622, 1.0000],
[198.2590, 209.8627, 1.0000],
[208.4310, 210.4628, 1.0000],
[178.5134, 218.2642, 1.0000],
[219.7997, 251.8704, 1.0000],
[162.3579, 269.2736, 1.0000],
[245.5289, 304.6800, 1.0000],
[138.4238, 330.4848, 1.0000],
[278.4382, 346.0876, 1.0000],
[153.3826, 374.8929, 1.0000],
[233.5618, 368.2917, 1.0000],
[225.7832, 367.6916, 1.0000],
[289.8069, 357.4897, 1.0000],
[245.5289, 389.8956, 1.0000],
[281.4300, 349.0882, 1.0000],
[209.0294, 389.8956, 1.0000]]], grad_fn=<CopySlices>), 'keypoints_scores': tensor([[16.0163, 16.6672, 15.8312, 4.6510, 14.2053, 8.8280, 9.1136, 12.2084,
12.1901, 13.8453, 10.7090, 5.5852, 7.5005, 11.3378, 9.3700, 8.2987,
8.4479],
[12.9326, 13.8158, 14.9053, 3.9368, 12.9585, 6.4240, 6.8328, 10.4227,
9.2907, 10.1066, 10.1019, 0.1822, 4.3057, -4.9904, -2.7409, -2.7874,
-3.9329]], grad_fn=<CopySlices>)}]
.. GENERATED FROM PYTHON SOURCE LINES 377-384
As we see the output contains a list of dictionaries.
The output list is of length batch_size.
We currently have just a single image so length of list is 1.
Each entry in the list corresponds to an input image,
and it is a dict with keys `boxes`, `labels`, `scores`, `keypoints` and `keypoint_scores`.
Each value associated to those keys has `num_instances` elements in it.
In our case above there are 2 instances detected in the image.
.. GENERATED FROM PYTHON SOURCE LINES 384-391
.. code-block:: default
kpts = outputs[0]['keypoints']
scores = outputs[0]['scores']
print(kpts)
print(scores)
.. rst-class:: sphx-glr-script-out
.. code-block:: none
tensor([[[208.0176, 214.2408, 1.0000],
[208.0176, 207.0375, 1.0000],
[197.8246, 210.6392, 1.0000],
[208.0176, 211.8398, 1.0000],
[178.6378, 217.8425, 1.0000],
[221.2085, 253.8590, 1.0000],
[160.6502, 269.4662, 1.0000],
[243.9929, 304.2822, 1.0000],
[138.4654, 328.8935, 1.0000],
[277.5698, 340.8990, 1.0000],
[153.4551, 374.5144, 1.0000],
[226.0052, 375.7150, 1.0000],
[226.0052, 370.3125, 1.0000],
[221.8081, 455.5516, 1.0000],
[273.9723, 448.9486, 1.0000],
[193.6275, 546.1932, 1.0000],
[273.3727, 545.5930, 1.0000]],
[[207.8327, 214.6636, 1.0000],
[207.2343, 207.4622, 1.0000],
[198.2590, 209.8627, 1.0000],
[208.4310, 210.4628, 1.0000],
[178.5134, 218.2642, 1.0000],
[219.7997, 251.8704, 1.0000],
[162.3579, 269.2736, 1.0000],
[245.5289, 304.6800, 1.0000],
[138.4238, 330.4848, 1.0000],
[278.4382, 346.0876, 1.0000],
[153.3826, 374.8929, 1.0000],
[233.5618, 368.2917, 1.0000],
[225.7832, 367.6916, 1.0000],
[289.8069, 357.4897, 1.0000],
[245.5289, 389.8956, 1.0000],
[281.4300, 349.0882, 1.0000],
[209.0294, 389.8956, 1.0000]]], grad_fn=<CopySlices>)
tensor([0.9998, 0.1070], grad_fn=<IndexBackward0>)
.. GENERATED FROM PYTHON SOURCE LINES 392-398
The KeypointRCNN model detects there are two instances in the image.
If you plot the boxes by using :func:`~draw_bounding_boxes`
you would recognize they are the person and the surfboard.
If we look at the scores, we will realize that the model is much more confident about the person than surfboard.
We could now set a threshold confidence and plot instances which we are confident enough.
Let us set a threshold of 0.75 and filter out the keypoints corresponding to the person.
.. GENERATED FROM PYTHON SOURCE LINES 398-405
.. code-block:: default
detect_threshold = 0.75
idx = torch.where(scores > detect_threshold)
keypoints = kpts[idx]
print(keypoints)
.. rst-class:: sphx-glr-script-out
.. code-block:: none
tensor([[[208.0176, 214.2408, 1.0000],
[208.0176, 207.0375, 1.0000],
[197.8246, 210.6392, 1.0000],
[208.0176, 211.8398, 1.0000],
[178.6378, 217.8425, 1.0000],
[221.2085, 253.8590, 1.0000],
[160.6502, 269.4662, 1.0000],
[243.9929, 304.2822, 1.0000],
[138.4654, 328.8935, 1.0000],
[277.5698, 340.8990, 1.0000],
[153.4551, 374.5144, 1.0000],
[226.0052, 375.7150, 1.0000],
[226.0052, 370.3125, 1.0000],
[221.8081, 455.5516, 1.0000],
[273.9723, 448.9486, 1.0000],
[193.6275, 546.1932, 1.0000],
[273.3727, 545.5930, 1.0000]]], grad_fn=<IndexBackward0>)
.. GENERATED FROM PYTHON SOURCE LINES 406-410
Great, now we have the keypoints corresponding to the person.
Each keypoint is represented by x, y coordinates and the visibility.
We can now use the :func:`~torchvision.utils.draw_keypoints` function to draw keypoints.
Note that the utility expects uint8 images.
.. GENERATED FROM PYTHON SOURCE LINES 410-416
.. code-block:: default
from torchvision.utils import draw_keypoints
res = draw_keypoints(person_int, keypoints, colors="blue", radius=3)
show(res)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_011.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_011.png
:class: sphx-glr-single-img
.. GENERATED FROM PYTHON SOURCE LINES 417-419
As we see the keypoints appear as colored circles over the image.
The coco keypoints for a person are ordered and represent the following list.\
.. GENERATED FROM PYTHON SOURCE LINES 419-427
.. code-block:: default
coco_keypoints = [
"nose", "left_eye", "right_eye", "left_ear", "right_ear",
"left_shoulder", "right_shoulder", "left_elbow", "right_elbow",
"left_wrist", "right_wrist", "left_hip", "right_hip",
"left_knee", "right_knee", "left_ankle", "right_ankle",
]
.. GENERATED FROM PYTHON SOURCE LINES 428-447
What if we are interested in joining the keypoints?
This is especially useful in creating pose detection or action recognition.
We can join the keypoints easily using the `connectivity` parameter.
A close observation would reveal that we would need to join the points in below
order to construct human skeleton.
nose -> left_eye -> left_ear. (0, 1), (1, 3)
nose -> right_eye -> right_ear. (0, 2), (2, 4)
nose -> left_shoulder -> left_elbow -> left_wrist. (0, 5), (5, 7), (7, 9)
nose -> right_shoulder -> right_elbow -> right_wrist. (0, 6), (6, 8), (8, 10)
left_shoulder -> left_hip -> left_knee -> left_ankle. (5, 11), (11, 13), (13, 15)
right_shoulder -> right_hip -> right_knee -> right_ankle. (6, 12), (12, 14), (14, 16)
We will create a list containing these keypoint ids to be connected.
.. GENERATED FROM PYTHON SOURCE LINES 447-453
.. code-block:: default
connect_skeleton = [
(0, 1), (0, 2), (1, 3), (2, 4), (0, 5), (0, 6), (5, 7), (6, 8),
(7, 9), (8, 10), (5, 11), (6, 12), (11, 13), (12, 14), (13, 15), (14, 16)
]
.. GENERATED FROM PYTHON SOURCE LINES 454-456
We pass the above list to the connectivity parameter to connect the keypoints.
.. GENERATED FROM PYTHON SOURCE LINES 456-459
.. code-block:: default
res = draw_keypoints(person_int, keypoints, connectivity=connect_skeleton, colors="blue", radius=4, width=3)
show(res)
.. image-sg:: /auto_examples/images/sphx_glr_plot_visualization_utils_012.png
:alt: plot visualization utils
:srcset: /auto_examples/images/sphx_glr_plot_visualization_utils_012.png
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-timing
**Total running time of the script:** ( 0 minutes 8.683 seconds)
.. _sphx_glr_download_auto_examples_plot_visualization_utils.py:
.. only:: html
.. container:: sphx-glr-footer sphx-glr-footer-example
.. container:: sphx-glr-download sphx-glr-download-python
:download:`Download Python source code: plot_visualization_utils.py <plot_visualization_utils.py>`
.. container:: sphx-glr-download sphx-glr-download-jupyter
:download:`Download Jupyter notebook: plot_visualization_utils.ipynb <plot_visualization_utils.ipynb>`
.. only:: html
.. rst-class:: sphx-glr-signature
`Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_