npr op• 資料種類:image2d → image2d
• 呼叫: import fullseye as fs; fs.ledger.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0)(要直接呼叫實作,import printpath; printpath.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0);從台帳取用則 opsprintpath.get("hatch_field"))
順著畫面的交叉排線 —— 方向來自結構張量。
> 以下的詳細說明為原文 —— 摘要與標題已翻譯。
The stroke direction is the local structure orientation (the existing
`structure_tensor_orientation`: strokes run *along* edges, not across them),
and the number of superposed hatch layers comes from the tone — one layer for
a light grey, up to *levels* for a dark one, each rotated by *cross_deg*.
★Why this earns its place: the direction is checkable against a picture
whose orientation is known by construction (a sine grating at 30° must give
strokes at 30°), and the tone is checkable by blurring the result. The usual
NPR routine offers neither.
Returns an `image2d`: 1 = paper, 0 = ink.
Raises `ValueError`: spacing below 2 px; levels below 1; non-positive
sigma; a non-finite or oversized image.
Limits: a single orientation per pixel, so crossings and junctions (where the
structure tensor is isotropic) get an arbitrary but locally smooth direction —
the coherence, not the orientation, is what says whether to trust it.
• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。
• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。
• 演算法的正典(作者・年份)與用途見上面的族使用指南。
• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py
image2d 作為輸入)stipple_points_from_image · stipple_energy · stroke_tone_error · halftone_screen · engrave_lines · mosaic_tiles_sites · mosaic_tiles_render · print_layer_defect_map
npr)halftone_screen · halftone_moire_period · engrave_lines · mosaic_tiles_sites · mosaic_tiles_render
*Provenance: printpath.py — PRINTPATH 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.