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 a quick visual evaluation of display performance based on AAPM Report 270 recommendations. MAIN FEATURES: - 18 grayscale squares (3 rows × 6 columns) covering gray levels 0-255 - Each square contains modulation patterns with 6-pixel vertical bars - Upper-left sub-squares: -5 gray levels contrast (darker bars) - Lower-right sub-squares: +5 gray levels contrast (lighter bars) - Special cases: First square (GL 0) and last square (GL 255) use ±3 contrast LARGE SQUARES (bottom): - Three 256×256 squares: Black (0), Mid-gray (128), White (255) - For luminance measurements and uniformity assessment - Can be used for bad pixel detection GRADIENT BAR (bottom): - Continuous 0-255 gradient spanning full width - Line patterns on right side verify pixel mapping - Useful for detecting bit depth issues and contouring artifacts CONTROLS: - Click and drag: Pan the pattern in any direction - Ctrl + Mouse wheel: Zoom in/out (1x to 10x) - ⟲ button (top-left): Reset zoom and panning to default - Window resize: Automatically resets view to fit new window size NOTES: - Bar patterns maintain fixed 6-pixel period regardless of zoom - Corner gradient patterns maintain fixed 2-pixel period - Pattern scales to fit window height while maintaining aspect ratio USAGE: - For a DICOM-conformant display, all 18 modulation patterns should be equally visible - The corner patterns (upper-left of first square, lower-right of last square) have lower contrast (3 gray levels) and may only be visible on highest-performance displays - Bar pattern periods may be scaled by system DPI settings