Image utilities¶
arkindex_worker.image ¶
Helper methods to download and open IIIF images, and manage polygons.
Classes¶
Functions¶
open_image ¶
open_image(
path, mode="RGB", rotation_angle=0, mirrored=False
)
Open an image from a path or a URL.
Warns: Prefer arkindex_worker.models.Element.open_image whenever possible.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
path |
str
|
Path or URL to open the image from. This parameter will be interpreted as a URL when it has a |
required |
mode |
Optional[str]
|
Pillow mode for the image. See the Pillow documentation. |
'RGB'
|
rotation_angle |
Optional[int]
|
Rotation angle to apply to the image, in degrees. If it is not a multiple of 90°, then the rotation can cause empty pixels of the mode’s default color to be added for padding. |
0
|
mirrored |
Optional[bool]
|
Whether or not to mirror the image horizontally. |
False
|
Returns:
Type | Description |
---|---|
Image
|
A Pillow image. |
Source code in arkindex_worker/image.py
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download_image ¶
download_image(url)
Download an image and open it with Pillow.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
url |
str
|
URL of the image. |
required |
Returns:
Type | Description |
---|---|
Image
|
A Pillow image. |
Source code in arkindex_worker/image.py
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polygon_bounding_box ¶
polygon_bounding_box(polygon)
Compute the rectangle bounding box of a polygon.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
polygon |
List[List[Union[int, float]]]
|
Polygon to get the bounding box of. |
required |
Returns:
Type | Description |
---|---|
BoundingBox
|
Bounding box of this polygon. |
Source code in arkindex_worker/image.py
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download_tiles ¶
download_tiles(url)
Reconstruct a full IIIF image on servers that cannot serve the full-sized image, using tiles.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
url |
str
|
URL of the image. |
required |
Returns:
Type | Description |
---|---|
Image
|
A Pillow image. |
Source code in arkindex_worker/image.py
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trim_polygon ¶
trim_polygon(polygon, image_width, image_height)
Trim a polygon to an image’s boundaries, with non-negative coordinates.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
polygon |
List[List[int]]
|
A polygon to trim. |
required |
image_width |
int
|
Width of the image. |
required |
image_height |
int
|
Height of the image. |
required |
Returns:
Type | Description |
---|---|
List[List[int]]
|
A polygon trimmed to the image’s bounds. Some points may appear as missing, as the trimming can deduplicate points. The first and last point are always equal, to reproduce the behavior of the Arkindex backend. |
Raises:
Type | Description |
---|---|
AssertionError
|
When argument types are invalid or when the trimmed polygon is entirely outside of the image’s bounds. |
Source code in arkindex_worker/image.py
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revert_orientation ¶
revert_orientation(element, polygon, reverse=False)
Update the coordinates of the polygon of a child element based on the orientation of its parent.
This method should be called before sending any polygon to Arkindex, to undo the possible orientation applied by arkindex_worker.models.Element.open_image.
In some cases, we want to apply the parent’s orientation on the child’s polygon instead. This is done
by enabling reverse=True
.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
element |
Union[Element, CachedElement]
|
Parent element. |
required |
polygon |
List[List[Union[int, float]]]
|
Polygon corresponding to the child element. |
required |
reverse |
Optional[bool]
|
Whether we should revert or apply the parent’s orientation. |
False
|
Returns:
Type | Description |
---|---|
List[List[int]]
|
A polygon with updated coordinates. |
Source code in arkindex_worker/image.py
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