Utils

draw_line

Draws a line on a given scene.

Parameters:

Name	Type	Description	Default
scene	ndarray	The scene on which the line will be drawn	required
start	Point	The starting point of the line	required
end	Point	The end point of the line	required
color	Color	The color of the line	required
thickness	int	The thickness of the line	2

Returns:

Type	Description
ndarray	np.ndarray: The scene with the line drawn on it

Source code in supervision/draw/utils.py

def draw_line(
    scene: np.ndarray, start: Point, end: Point, color: Color, thickness: int = 2
) -> np.ndarray:
    """
    Draws a line on a given scene.

    Parameters:
        scene (np.ndarray): The scene on which the line will be drawn
        start (Point): The starting point of the line
        end (Point): The end point of the line
        color (Color): The color of the line
        thickness (int): The thickness of the line

    Returns:
        np.ndarray: The scene with the line drawn on it
    """
    cv2.line(
        scene,
        start.as_xy_int_tuple(),
        end.as_xy_int_tuple(),
        color.as_bgr(),
        thickness=thickness,
    )
    return scene

draw_rectangle

Draws a rectangle on an image.

Parameters:

Name	Type	Description	Default
scene	ndarray	The scene on which the rectangle will be drawn	required
rect	Rect	The rectangle to be drawn	required
color	Color	The color of the rectangle	required
thickness	int	The thickness of the rectangle border	2

Returns:

Type	Description
ndarray	np.ndarray: The scene with the rectangle drawn on it

Source code in supervision/draw/utils.py

def draw_rectangle(
    scene: np.ndarray, rect: Rect, color: Color, thickness: int = 2
) -> np.ndarray:
    """
    Draws a rectangle on an image.

    Parameters:
        scene (np.ndarray): The scene on which the rectangle will be drawn
        rect (Rect): The rectangle to be drawn
        color (Color): The color of the rectangle
        thickness (int): The thickness of the rectangle border

    Returns:
        np.ndarray: The scene with the rectangle drawn on it
    """
    cv2.rectangle(
        scene,
        rect.top_left.as_xy_int_tuple(),
        rect.bottom_right.as_xy_int_tuple(),
        color.as_bgr(),
        thickness=thickness,
    )
    return scene

draw_filled_rectangle

Draws a filled rectangle on an image.

Parameters:

Name	Type	Description	Default
scene	ndarray	The scene on which the rectangle will be drawn	required
rect	Rect	The rectangle to be drawn	required
color	Color	The color of the rectangle	required

Returns:

Type	Description
ndarray	np.ndarray: The scene with the rectangle drawn on it

Source code in supervision/draw/utils.py

def draw_filled_rectangle(scene: np.ndarray, rect: Rect, color: Color) -> np.ndarray:
    """
    Draws a filled rectangle on an image.

    Parameters:
        scene (np.ndarray): The scene on which the rectangle will be drawn
        rect (Rect): The rectangle to be drawn
        color (Color): The color of the rectangle

    Returns:
        np.ndarray: The scene with the rectangle drawn on it
    """
    cv2.rectangle(
        scene,
        rect.top_left.as_xy_int_tuple(),
        rect.bottom_right.as_xy_int_tuple(),
        color.as_bgr(),
        -1,
    )
    return scene

draw_polygon

Draw a polygon on a scene.

Parameters:

Name	Type	Description	Default
scene	ndarray	The scene to draw the polygon on.	required
polygon	ndarray	The polygon to be drawn, given as a list of vertices.	required
color	Color	The color of the polygon.	required
thickness	int	The thickness of the polygon lines, by default 2.	2

Returns:

Type	Description
ndarray	np.ndarray: The scene with the polygon drawn on it.

Source code in supervision/draw/utils.py

def draw_polygon(
    scene: np.ndarray, polygon: np.ndarray, color: Color, thickness: int = 2
) -> np.ndarray:
    """Draw a polygon on a scene.

    Parameters:
        scene (np.ndarray): The scene to draw the polygon on.
        polygon (np.ndarray): The polygon to be drawn, given as a list of vertices.
        color (Color): The color of the polygon.
        thickness (int, optional): The thickness of the polygon lines, by default 2.

    Returns:
        np.ndarray: The scene with the polygon drawn on it.
    """
    cv2.polylines(
        scene, [polygon], isClosed=True, color=color.as_bgr(), thickness=thickness
    )
    return scene

draw_text

Draw text with background on a scene.

Parameters:

Name	Type	Description	Default
scene	ndarray	A 2-dimensional numpy ndarray representing an image or scene	required
text	str	The text to be drawn.	required
text_anchor	Point	The anchor point for the text, represented as a Point object with x and y attributes.	required
text_color	Color	The color of the text. Defaults to black.	BLACK
text_scale	float	The scale of the text. Defaults to 0.5.	0.5
text_thickness	int	The thickness of the text. Defaults to 1.	1
text_padding	int	The amount of padding to add around the text when drawing a rectangle in the background. Defaults to 10.	10
text_font	int	The font to use for the text. Defaults to cv2.FONT_HERSHEY_SIMPLEX.	FONT_HERSHEY_SIMPLEX
background_color	Color	The color of the background rectangle, if one is to be drawn. Defaults to None.	None

Returns:

Type	Description
ndarray	np.ndarray: The input scene with the text drawn on it.

Examples:

import numpy as np

scene = np.zeros((100, 100, 3), dtype=np.uint8)
text_anchor = Point(x=50, y=50)
scene = draw_text(scene=scene, text="Hello, world!",text_anchor=text_anchor)

Source code in supervision/draw/utils.py

def draw_text(
    scene: np.ndarray,
    text: str,
    text_anchor: Point,
    text_color: Color = Color.BLACK,
    text_scale: float = 0.5,
    text_thickness: int = 1,
    text_padding: int = 10,
    text_font: int = cv2.FONT_HERSHEY_SIMPLEX,
    background_color: Optional[Color] = None,
) -> np.ndarray:
    """
    Draw text with background on a scene.

    Parameters:
        scene (np.ndarray): A 2-dimensional numpy ndarray representing an image or scene
        text (str): The text to be drawn.
        text_anchor (Point): The anchor point for the text, represented as a
            Point object with x and y attributes.
        text_color (Color, optional): The color of the text. Defaults to black.
        text_scale (float, optional): The scale of the text. Defaults to 0.5.
        text_thickness (int, optional): The thickness of the text. Defaults to 1.
        text_padding (int, optional): The amount of padding to add around the text
            when drawing a rectangle in the background. Defaults to 10.
        text_font (int, optional): The font to use for the text.
            Defaults to cv2.FONT_HERSHEY_SIMPLEX.
        background_color (Color, optional): The color of the background rectangle,
            if one is to be drawn. Defaults to None.

    Returns:
        np.ndarray: The input scene with the text drawn on it.

    Examples:
        ```python
        import numpy as np

        scene = np.zeros((100, 100, 3), dtype=np.uint8)
        text_anchor = Point(x=50, y=50)
        scene = draw_text(scene=scene, text="Hello, world!",text_anchor=text_anchor)
        ```
    """
    text_width, text_height = cv2.getTextSize(
        text=text,
        fontFace=text_font,
        fontScale=text_scale,
        thickness=text_thickness,
    )[0]
    text_rect = Rect(
        x=text_anchor.x - text_width // 2,
        y=text_anchor.y - text_height // 2,
        width=text_width,
        height=text_height,
    ).pad(text_padding)

    if background_color is not None:
        scene = draw_filled_rectangle(
            scene=scene, rect=text_rect, color=background_color
        )

    cv2.putText(
        img=scene,
        text=text,
        org=(text_anchor.x - text_width // 2, text_anchor.y + text_height // 2),
        fontFace=text_font,
        fontScale=text_scale,
        color=text_color.as_bgr(),
        thickness=text_thickness,
        lineType=cv2.LINE_AA,
    )
    return scene

draw_image

Draws an image onto a given scene with specified opacity and dimensions.

Parameters:

Name	Type	Description	Default
scene	ndarray	Background image where the new image will be drawn.	required
image	Union[str, ndarray]	Image to draw.	required
opacity	float	Opacity of the image to be drawn.	required
rect	Rect	Rectangle specifying where to draw the image.	required

Returns:

Type	Description
ndarray	np.ndarray: The updated scene.

Raises:

Type	Description
FileNotFoundError	If the image path does not exist.
ValueError	For invalid opacity or rectangle dimensions.

Source code in supervision/draw/utils.py

def draw_image(
    scene: np.ndarray, image: Union[str, np.ndarray], opacity: float, rect: Rect
) -> np.ndarray:
    """
    Draws an image onto a given scene with specified opacity and dimensions.

    Args:
        scene (np.ndarray): Background image where the new image will be drawn.
        image (Union[str, np.ndarray]): Image to draw.
        opacity (float): Opacity of the image to be drawn.
        rect (Rect): Rectangle specifying where to draw the image.

    Returns:
        np.ndarray: The updated scene.

    Raises:
        FileNotFoundError: If the image path does not exist.
        ValueError: For invalid opacity or rectangle dimensions.
    """

    # Validate and load image
    if isinstance(image, str):
        if not os.path.exists(image):
            raise FileNotFoundError(f"Image path ('{image}') does not exist.")
        image = cv2.imread(image, cv2.IMREAD_UNCHANGED)

    # Validate opacity
    if not 0.0 <= opacity <= 1.0:
        raise ValueError("Opacity must be between 0.0 and 1.0.")

    # Validate rectangle dimensions
    if (
        rect.x < 0
        or rect.y < 0
        or rect.x + rect.width > scene.shape[1]
        or rect.y + rect.height > scene.shape[0]
    ):
        raise ValueError("Invalid rectangle dimensions.")

    # Resize and isolate alpha channel
    image = cv2.resize(image, (rect.width, rect.height))
    alpha_channel = (
        image[:, :, 3]
        if image.shape[2] == 4
        else np.ones((rect.height, rect.width), dtype=image.dtype) * 255
    )
    alpha_scaled = cv2.convertScaleAbs(alpha_channel * opacity)

    # Perform blending
    scene_roi = scene[rect.y : rect.y + rect.height, rect.x : rect.x + rect.width]
    alpha_float = alpha_scaled.astype(np.float32) / 255.0
    blended_roi = cv2.convertScaleAbs(
        (1 - alpha_float[..., np.newaxis]) * scene_roi
        + alpha_float[..., np.newaxis] * image[:, :, :3]
    )

    # Update the scene
    scene[rect.y : rect.y + rect.height, rect.x : rect.x + rect.width] = blended_roi

    return scene

calculate_dynamic_font_scale

Calculate a dynamic font scale based on the resolution of an image.

Parameters:

Name	Type	Description	Default
resolution_wh	Tuple[int, int]	A tuple representing the width and height of the image.	required

Returns:

Name	Type	Description
float	float	The calculated font scale factor.

Source code in supervision/draw/utils.py

def calculate_dynamic_text_scale(resolution_wh: Tuple[int, int]) -> float:
    """
    Calculate a dynamic font scale based on the resolution of an image.

    Parameters:
         resolution_wh (Tuple[int, int]): A tuple representing the width and height
                 of the image.

    Returns:
         float: The calculated font scale factor.
    """
    return min(resolution_wh) * 1e-3

calculate_dynamic_line_thickness

Calculate a dynamic line thickness based on the resolution of an image.

Parameters:

Name	Type	Description	Default
resolution_wh	Tuple[int, int]	A tuple representing the width and height of the image.	required

Returns:

Name	Type	Description
int	int	The calculated line thickness in pixels.

Source code in supervision/draw/utils.py

def calculate_dynamic_line_thickness(resolution_wh: Tuple[int, int]) -> int:
    """
    Calculate a dynamic line thickness based on the resolution of an image.

    Parameters:
        resolution_wh (Tuple[int, int]): A tuple representing the width and height
                of the image.

    Returns:
        int: The calculated line thickness in pixels.
    """
    min_dimension = min(resolution_wh)
    if min_dimension < 480:
        return 2
    if min_dimension < 720:
        return 2
    if min_dimension < 1080:
        return 2
    if min_dimension < 2160:
        return 4
    else:
        return 4

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