vis4d.vis.image.canvas.pillow_backend

Pillow backend implementation to draw on images.

Functions

load_default_font()

Load a "better than nothing" default font.

Classes

PillowCanvasBackend([font])

Canvas backend using Pillow.

class PillowCanvasBackend(font=None)

Canvas backend using Pillow.

Creates a new canvas backend.

Parameters:

font (ImageFont) – Pillow font to use for the label.

as_numpy_image()

Returns the current canvas as numpy image.

Raises:

ValueError – If the canvas is not initialized.

Return type:

ndarray[Any, dtype[uint8]]

create_canvas(image=None, image_hw=None)

Creates a new canvas with a given image or shape internally.

Either provide a background image or the desired height, width of the canvas.

Parameters:

• image (np.array[uint8] | None) – Numpy array with a background image

• image_hw (tuple[int, int] | None) – height, width of the canvas

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

draw_bitmap(bitmap, color, top_left_corner=(0, 0), alpha=0.5)

Draws a binary mask onto the given canvas.

Parameters:

• bitmap (ndarray) – The binary mask to draw.

• color (tuple[int, int, int]) – Color of the box [0,255].

• top_left_corner (tuple(float, float)) – Coordinates of top left corner of the bitmap.

• alpha (float) – Alpha value for transparency of this mask.

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

draw_box(corners, color, width=1)

Draws a box onto the given canvas.

Parameters:

• corners (list[float]) – Containing [x1,y2,x2,y2] the corners of the box.

• color (tuple[int, int, int]) – Color of the box [0,255].

• width (int, optional) – Line width. Defaults to 1.

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

draw_box_3d(corners, color, intrinsics, width=0, camera_near_clip=0.15)

Draws a 3D box onto the given canvas.

Return type:

None

draw_circle(center, color, radius=2)

Draw a circle onto canvas.

Parameters:

• center (tuple[float, float]) – Center of the circle.

• color (tuple[int, int, int]) – Color of the circle.

• radius (int, optional) – Radius of the circle. Defaults to 2.

Return type:

None

draw_line(point1, point2, color, width=0)

Draw a line onto canvas from point 1 to 2.

Parameters:

• point1 (tuple[float, float]) – Start point (2D pixel coordinates).

• point2 (tuple[float, float]) – End point (2D pixel coordinates).

• color (tuple[int, int, int]) – Color of the line.

• width (int, optional) – Line width. Defaults to 0.

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

draw_rotated_box(corners, color, width=0)

Draws a box onto the given canvas.

Corner ordering:

2. +———+ (3) | | | | | |

0. +———+ (1)

Parameters:

• corners (list[tuple[float, float]]) – Containing the four corners of the box.

• color (tuple[int, int, int]) – Color of the box [0,255].

• width (int, optional) – Line width. Defaults to 0.

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

draw_text(position, text, color=(255, 255, 255))

Draw text onto canvas at given position.

Parameters:

• position (tuple[float, float]) – x,y position where the text will start.

• text (str) – Text to be placed at the given location.

• color (tuple[int, int, int], optional) – Text color. Defaults to (255, 255, 255).

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

save_to_disk(image_path)

Writes the current canvas to disk.

Parameters:

image_path (str) – Full image path (with file name and ending).

Raises:

ValueError – If the canvas is not initialized.

Return type:

None

load_default_font()

Load a “better than nothing” default font.

Return type:

ImageFont