npr op• 数据种类:image2d → image2d
• 调用: import fullseye as fs; fs.ledger.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0)(要直接调用实现,import printpath; printpath.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0);从台账取用则 opsprintpath.get("hatch_field"))
顺着画面的交叉排线 —— 方向来自结构张量。
> 以下的详细说明为原文 —— 摘要与标题已翻译。
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.
• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。
• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。
• 算法的正典(作者・年份)与用途见上面的族使用指南。
• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py
image2d 作为输入)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 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.