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Constructors for ImageRegion #71

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236 changes: 236 additions & 0 deletions src/highdicom/sr/content.py
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Original file line number Diff line number Diff line change
Expand Up @@ -468,6 +468,20 @@ def __init__(
of the source image
(default: ``highdicom.sr.enum.PixelOriginInterpretationValues.VOLUME``)

Raises
------
ValueError
If the shape of the graphic data array is invalid for the graphic
type used. If the graphic type parameter is ``MULTIPOINT``.

Notes
-----
See
`http://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.18.6.html#sect_C.18.6.1.1`_
for an explanation of the interpretation of the graphic data elements
for each graphic type or use the :method:`from_circle`, :method:`from_box`, or
:method:`from_ellipse` methods for convenience.

""" # noqa
graphic_type = GraphicTypeValues(graphic_type)
if graphic_type == GraphicTypeValues.MULTIPOINT:
Expand Down Expand Up @@ -500,6 +514,228 @@ def __init__(
)
self.ContentSequence = [source_image]

@classmethod
def from_circle(
cls,
xc: float,
yc: float,
radius: float,
source_image: SourceImageForRegion,
pixel_origin_interpretation: Optional[
Union[PixelOriginInterpretationValues, str]
] = None
) -> 'ImageRegion':
"""Construct an ImageRegion representing a circle.

This is a convenience wrapper that correctly populates the graphic
data from the named parameters.

Parameters
----------
xc: float
Zero-based x-coordinate (column index) of the center of the
circle, in pixel units from the left of the image.
yc: float
Zero-based y-coordinate (row index) of the center of the circle,
in pixel units from the top of the image.
radius: float
Radius of the circle, in pixel units.

Returns
-------
ImageRegion
Image Region describing the specified circle using the GraphicType
``CIRCLE``.

Raises
------
ValueError
If any of the parameters are negative.

"""
if radius < 0.0:
raise ValueError("The radius may not be negative.")
if xc < 0.0 or yc < 0.0:
raise ValueError("Center coordinates may not be negative.")

# The first point is the central pixel. The second point is a pixel on
# the perimeter of the circle.
graphic_data = np.array(
[
[xc, yc],
[xc + radius, yc]
]
)

return cls(
graphic_type=GraphicTypeValues.CIRCLE,
graphic_data=graphic_data,
source_image=source_image,
pixel_origin_interpretation=pixel_origin_interpretation
)

@classmethod
def from_box(
cls,
left: float,
right: float,
top: float,
bottom: float,
source_image: SourceImageForRegion,
pixel_origin_interpretation: Optional[
Union[PixelOriginInterpretationValues, str]
] = None
) -> 'ImageRegion':
"""Construct an ImageRegion representing an axis-aligned box.

Note that there is no specialized way to represent a box using graphic
data. This is a convenience wrapper that correctly represents an
axis-aligned box as a special case of a closed polyline.

Parameters
----------
left: float
Zero-based x-coordinate (column index) of the left side of the
box, in pixel units from the left of the image.
right: float
Zero-based x-coordinate (column index) of the right side of the
box, in pixel units from the left of the image.
top: float
Zero-based y-coordinate (row index) of the top of the
box, in pixel units from the top of the image.
bottom: float
Zero-based y-coordinate (row index) of the bottom of the
box, in pixel units from the top of the image.

Returns
-------
ImageRegion
Image Region describing the specified box using the GraphicType
``POLYLINE``. The points are traversed clockwise from the top left
and the first and last points of the box are the same to encode a
closed box.

Raises
------
ValueError
If any of the parameters are negative.

"""
if left < 0.0 or top < 0.0:
raise ValueError("Image coordinates may not be negative.")

if right < left:
raise ValueError("Right must be greater than left.")
if bottom < top:
raise ValueError("Bottom must be greater than top.")

# Points in clockwise order from top left
graphic_data = np.array(
[
[left, top],
[right, top],
[right, bottom],
[left, bottom],
[left, top], # close the polygon
]
)

return cls(
graphic_type=GraphicTypeValues.POLYLINE,
graphic_data=graphic_data,
source_image=source_image,
pixel_origin_interpretation=pixel_origin_interpretation
)

@classmethod
def from_ellipse(
cls,
xc: float,
yc: float,
Comment on lines +653 to +654
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We should avoid x and y here and use row and col instead, because the axis of the coordinate system (pixel matrix) are Rows and Columns.

major_axis: float,
minor_axis: float,
angle: float,
source_image: SourceImageForRegion,
pixel_origin_interpretation: Optional[
Union[PixelOriginInterpretationValues, str]
] = None
) -> 'ImageRegion':
"""Construct an ImageRegion representing an ellipse.

This is a convenience wrapper that correctly populates the graphic
data from the named parameters.

Parameters
----------
xc: float
Zero-based x-coordinate (column index) of the center of the
circle, in pixel units from the left of the image.
yc: float
Zero-based y-coordinate (row index) of the center of the circle,
in pixel units from the top of the image.
major_axis: float
Length of the major axis of the ellipse in pixel units.
minor_axis: float
Length of the minor axis of the ellipse in pixel units.
angle: float
Angle, in radians, of the major axis from the horizontal, with
positive angles tilting the major axis towards the top of the
image.

Returns
-------
ImageRegion
Image Region describing the specified circle using the GraphicType
``ELLIPSE``.

Raises
------
ValueError
If any of the parameters are negative.

"""
if xc < 0.0 or yc < 0.0:
raise ValueError("Center coordinates may not be negative.")
if minor_axis < 0.0:
raise ValueError("Length of the minor axis must be positive.")
if major_axis < minor_axis:
raise ValueError(
"Length of the major axis must be greater than the length of "
"the minor axis."
)

center = np.array([xc, yc])

semi_major_axis_vec = np.array(
[
0.5 * major_axis * np.cos(angle),
0.5 * major_axis * np.sin(angle)
]
)
semi_minor_axis_vec = np.array(
[
0.5 * minor_axis * np.sin(angle),
0.5 * minor_axis * -np.cos(angle)
]
)

# Ends of the minor axis
graphic_data = np.stack(
[
center - semi_major_axis_vec,
center + semi_major_axis_vec,
center - semi_minor_axis_vec,
center + semi_minor_axis_vec
]
)

return cls(
graphic_type=GraphicTypeValues.ELLIPSE,
graphic_data=graphic_data,
source_image=source_image,
pixel_origin_interpretation=pixel_origin_interpretation
)


class ImageRegion3D(Scoord3DContentItem):

Expand Down