npr op• Data kinds: image2d → image2d
• Call: import fullseye as fs; fs.ledger.halftone_screen(image, lpi=60.0, angle_deg=45.0, pixel_um=25.4, sharpness=8.0) (implementation को सीधे call करना हो तो import printpath; printpath.halftone_screen(image, lpi=60.0, angle_deg=45.0, pixel_um=25.4, sharpness=8.0), registry से लेना हो तो opsprintpath.get("halftone_screen"))
पारंपरिक घुमाई गई halftone screen — dot जिनका क्षेत्रफल tone को दर्शाता है।
> नीचे का विस्तृत विवरण मूल text में है — सारांश और headings का अनुवाद हो चुका है।
Thresholds the image against a rotated periodic spot function (the product of two shifted cosines, the classical round-dot screen). *lpi* is lines per inch and *pixel_um* the pixel pitch, so the screen frequency in pixels follows the printing convention rather than a bare "period in pixels".
★Why this earns its place: two screens at different angles beat against one another, and the period and direction of that moiré are a closed form (halftone_moire_period) that can be predicted *before* anything is drawn and then measured out of the image. That is why newspaper printing puts the plates at 15°/45°/75° — the beat is pushed to a frequency the eye does not resolve — and this op lets that be shown as numbers, not folklore.
image : 2-D array in [0, 1]
Tone; 0 prints solid, 1 prints blank (the ink is 1 - image).
lpi : float
Screen ruling, lines per inch. Newspapers use 65-85, magazines 133-175.
angle_deg : float
Screen angle. The classical set is K 45°, M 75°, C 15°, Y 0°.
pixel_um : float
Pixel pitch in micrometres (25.4 um = 1000 dpi).
sharpness : float
Edge hardness of the dot; large values give a hard threshold.
Returns an image2d: 1 = paper, 0 = ink.
Raises ValueError: non-positive lpi, pixel pitch or sharpness; a screen period below 2 px (it would alias — reported, never silently drawn); a non-finite or oversized image.
Limits: this is a *screen*, not a printer. Dot gain, ink spread and registration error are not modelled, so measured ink is the geometric coverage and will read lighter than a real press.
• Sample data catalog (DL URL / license) — 2-D के लिए skimage.data (BSD/public) + synthetic, 3-D के लिए real data sources (Stanford/PDS आदि) के DL URL।
• Operators का स्रोत और संदर्भ — इस op family के मूल research/methods के स्रोत।
• Algorithm का मानक स्रोत (लेखक, वर्ष) और उपयोग ऊपर की family usage guide में दिए गए हैं।
• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py
• poc_print_registration — py -3.11 examples/poc_print_registration.py
image2d को input के रूप में लेते हैं)stipple_points_from_image · stipple_energy · stroke_tone_error · engrave_lines · hatch_field · mosaic_tiles_sites · mosaic_tiles_render · print_layer_defect_map
npr)halftone_moire_period · engrave_lines · hatch_field · mosaic_tiles_sites · mosaic_tiles_render
*Provenance: printpath.py — PRINTPATH operator registry. यह per-op note tools/opdocs.py md से अपने-आप generate होता है (हाथ से edit न करें)।*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.