Principle:PeterL1n BackgroundMattingV2 Realtime display

Knowledge Sources	OpenCV HighGUI BackgroundMattingV2
Domains	Visualization, Realtime_Systems
Last Updated	2026-02-09 00:00 GMT

Overview

An interactive display wrapper that renders processed video frames in a resizable OpenCV window with FPS tracking and keyboard input handling.

Description

Realtime display provides a user interface for interactive matting applications. It combines three concerns:

• Frame display: Rendering the processed matting output in an OpenCV window using cv2.imshow
• FPS tracking: Computing an exponentially moving average of frames per second for performance monitoring, overlaid as text on the display
• Keyboard input: Polling for key presses to support interactive controls (e.g., B to capture background, Q to quit)

The FPS tracker uses an EMA (exponential moving average) with a configurable ratio to smooth out frame-to-frame timing variations.

Usage

Use this principle in interactive real-time matting demos. The display is instantiated once at startup with a window title and dimensions. In the main loop, call step(image) to update the display and check for key presses.

Theoretical Basis

FPS Estimation: $fp{s}_{avg}=\alpha \cdot fp{s}_{sample}+(1-\alpha )\cdot fp{s}_{avg}$

where α is the smoothing ratio (default 0.5) and fps_sample = 1 / Δt.

Event Loop Pattern:

# Abstract display loop
while True:
    frame = process_frame()
    key = display.step(frame)  # show frame, get keypress
    if key == 'q':
        exit()
    elif key == 'b':
        capture_background()

Related Pages

Implemented By

• Implementation:PeterL1n_BackgroundMattingV2_Displayer