PATTERN DESCRIPTION: This pattern provides a quick visual evaluation of display performance based on AAPM Task Group 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 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.