09b820efbe
The old displacement-map approach shifted entire rows by a parabolic profile, creating a circle/barrel distortion. The actual problem is a linear vertical shear: after deskew aligns horizontal lines, the vertical column edges are still tilted by ~0.5°. New approach: - Detect shear angle from strongest vertical edge slope (not curvature) - Apply cv2.warpAffine shear to straighten vertical features - Manual slider: -2.0° to +2.0° in 0.05° steps - Slider initializes to auto-detected shear angle - Ground truth question: "Spalten vertikal ausgerichtet?" Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>