Your OS is applying pixel scaling to this browser. The bar patterns of this test pattern may not be displayed at the correct frequency.

PATTERN DESCRIPTION: This pattern provides visual evaluation of display performance based on the AAPM TG18-OIQ specification (equivalent to TG18-QC without Cx patterns). It scales to fill the browser window using a 102-pixel grid pitch referenced to a 1024x1024 pattern. GRAY STEPS: - 16 cells covering gray levels 8–248 in equal steps (16 gray levels per step) - Include low-contrast corner patches (±4 gray levels) - Black cell (0): centered 50% sub-patch at gray 13 (+5%) - White cell (255): centered 50% sub-patch at gray 242 (-5%) LUMINANCE RAMPS: - Left ramp: 255 (top) → 0 (bottom) - Right ramp: 0 (top) → 255 (bottom) WINDOW RESPONSE BANDS (above gray step grid): - Outer band: black over white - Inner strips: white over black - For evaluating video signal artifacts QUALITY CONTROL PANELS (below gray step grid): - Three regions: black (0), mid-gray (128), white (255) - Each contains "QUALITY CONTROL" text with per-letter contrast - Q = ±14 gray levels, decreasing by 1 to L = ±1 gray level CROSSTALK SECTION (above window bands): - White band over black band - For evaluating pixel crosstalk SPATIAL RESOLUTION FEATURES: - 5 instances: center and four window corners - Left half: high contrast (0/255) - Right half: low contrast (128/130) - Each half has 4 quadrants: vertical 2 px/lp, vertical 4 px/lp, horizontal 2 px/lp, horizontal 4 px/lp - Bar pitch is fixed in screen pixels regardless of zoom level CONTROLS: - Click and drag: Pan - Ctrl + Mouse wheel: Zoom (1x–10x) - ⟲: Reset view - Window resize: Auto-reset NOTES: - Bar pattern periods may be affected by OS display scaling (warning message displayed at pattern load) - Pattern scales to fit the window dimensions