Overlay Drawing

helios.overlay draws simple shapes and text from CV Python. CV C++ provides the same features under Helios::Overlay.

Overlay calls belong inside process(frame).

Targets

Python	C++	Draws on
`overlay.FRAME`	`Target::Frame`	Processed video frame
`overlay.FUSER`	`Target::Fuser`	Fuser output
`overlay.BOTH`	`Target::Both`	Both outputs

The default target is BOTH, so a drawing appears on the processed frame and the Fuser output. Set FRAME or FUSER explicitly when only one output should receive it.

Python Example

python

from helios import overlay


class CVWorker:
    def __init__(self, width, height):
        pass

    def process(self, frame):
        overlay.rect(
            100, 100, 300, 220,
            color=(0, 255, 0),
            thickness=2,
            target=overlay.BOTH,
        )
        overlay.circle(
            200, 160, 18,
            color=(255, 0, 0),
            filled=True,
        )
        overlay.text(
            "TARGET",
            200, 90,
            color=(255, 255, 255),
            background_color=(0, 0, 0),
            background_alpha=140,
            padding=5,
            anchor=overlay.BOTTOM_CENTER,
        )

Overlay colors use RGB order. A four-value color tuple may include alpha, and an explicit alpha= value takes priority.

Primitives

python

overlay.line(x1, y1, x2, y2, color=(255, 255, 255),
             thickness=1, target=overlay.BOTH, alpha=None,
             space=overlay.PIXELS)

overlay.rect(x1, y1, x2, y2, color=(255, 255, 255),
             thickness=1, target=overlay.BOTH, alpha=None,
             filled=False, space=overlay.PIXELS)

overlay.circle(x, y, radius, color=(255, 255, 255),
               thickness=1, target=overlay.BOTH, alpha=None,
               filled=False, space=overlay.PIXELS)

overlay.text(value, x, y, color=(255, 255, 255), scale=2,
             target=overlay.BOTH, alpha=None,
             background_color=None, background_alpha=None,
             padding=0, anchor=overlay.TOP_LEFT,
             space=overlay.PIXELS)

overlay.rectangle(...) is an alias for overlay.rect(...). A rectangle or circle is filled when filled=True or its thickness is zero or negative.

Coordinates and Text Anchors

overlay.PIXELS uses the current frame's pixel coordinates. overlay.DESIGN_1080P lets a fixed HUD layout scale from a 1920×1080 design.

Text anchors are:

TOP_LEFT, TOP_CENTER, TOP_RIGHT
CENTER_LEFT, CENTER, CENTER_RIGHT
BOTTOM_LEFT, BOTTOM_CENTER, BOTTOM_RIGHT

When background_color is set without background_alpha, the background uses a semi-transparent default.

C++

cpp

Helios::Overlay::rect(
    100, 100, 300, 220,
    Helios::Overlay::Color{0, 255, 0},
    2,
    Helios::Overlay::Target::Both);

Helios::Overlay::text(
    200, 90,
    "TARGET",
    Helios::Overlay::Color{255, 255, 255},
    2,
    Helios::Overlay::Target::Fuser,
    Helios::Overlay::TextAnchor::BottomCenter);

C++ also provides line, circle, coordinate-space selection, alpha colors, text backgrounds, and OpenCV convenience overloads. Helios::Overlay::Color uses RGB; OpenCV cv::Scalar overloads use their usual BGR order.

Use OpenCV drawing when a script needs OpenCV-specific fonts, contours, polygons, ellipses, or line styles.

Raw Video Preview

Enable Preferences → Other → Video Display → Disable Overlay Drawing when you need to inspect the unannotated video. Helios continues script, inference, and OCR processing and still produces results, but skips their drawing on Video Display.