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PATTERN DESCRIPTION: This pattern provides comprehensive evaluation of display performance based on AAPM Report 270 recommendations. It is based on the TG18-PQC design. MAIN FEATURES: - 18 horizontal grayscale bars (0-255 in 15 gray level steps) - Multiple modulation patterns at varying frequencies and contrasts - High-contrast line pair patterns in top/bottom regions - Vertical gradient bars with modulation for uniformity assessment MODULATION PATTERNS: - Left region: Horizontal modulation at 4 frequencies (18, 12, 6, 4 pixels) - Inner columns: 2 gray level contrast - Outer columns: 8 gray level contrast - Right region: Vertical modulation at 4 frequencies (4, 6, 12, 18 pixels) - Inner columns: 2 gray level contrast - Outer columns: 8 gray level contrast LINE PAIR PATTERNS (Top/Bottom): - 6 line pair patterns at different frequencies (2, 4, 6 pixels) - High contrast (0/128 or 128/255) for resolution assessment SIDE GRADIENTS: - Full vertical gradients (0-255), each with a center strip carrying a ±3 gray level sinusoid: period 4π (≈12.6 px) left, 3π (≈9.4 px) right - For uniformity and gradient linearity evaluation CONTROLS: - Click and drag: Pan the pattern in any direction - Mouse wheel: Zoom in/out (1x to 10x) - ⟲ button (top-left) or R: Reset zoom and panning to default - ? button or H: Show/hide this help - Window resize: Automatically resets view to fit new window size NOTES: - Modulation and line-pair periods are fixed in display pixels and do not change with zoom - Pattern scales to fit window height while maintaining aspect ratio - Bar patterns are drawn in display pixels at any OS scaling or browser zoom. A browser that cannot report the exact canvas size at a fractional scaling shows a notice on load. - macOS: use the display's default resolution. Scaled resolutions resample the whole screen after the browser draws, which no web page can detect or undo. USAGE: On a DICOM-conformant display, each frequency/contrast pair should be equally visible at every gray level. The visibility between different frequencies may vary. The modulation within the grayscale ramps should appear uniform at all levels. The high-contrast line pairs at the top and bottom should appear crisp.