BWRECT(1)

🎀 BWRECT(1) — the bwrect girlies' guide 🎀

okay so real quick, this is bwrect from the BRL-CAD fam, and bestie, it's lowkey one of the most useful little tools in the whole toolbox. it does exactly one thing and it does it slayfully. 💅

✨ NAME ✨

bwrect — extract a rectangle from a black and white bw file. that's it. that's the whole vibe. 🫶

🌸 SYNOPSIS 🌸

bwrect [-s squaresize] [-w width] [-n height] [-S out_squaresize] [-W out_width] [-N out_height] [-x xorig] [-y yorig] [-o out_file.bw] [file.bw] [> out_file.bw]

💖 DESCRIPTION 💖

so what bwrect does is it goes into a black and white bw(5) format file and pulls out a rectangular region. like cropping a photo for the grid, except it's a bw file and it's iconic. ✨

the default input image size is 512x512. but here's the thing you cannot skip, bestie — the output width and height must be explicitly specified (using -W and -N, or -S), because they default to zero. so if you forget, you get nothing. it's giving "no thoughts, head empty." 😭

no input file? no problem — bwrect reads from standard input. no output file via -o? also fine — it writes to standard output. which means this utility is literally built to live in your pipelines. main character energy, fr fr. 🦋

🔥 OPTIONS 🔥

• -s squaresize — sets both the width and height of the input image to squaresize in pixels. one flag, two jobs, efficient queen. 👑
• -w width — specifies the width of the input image in pixels (default is 512).
• -n height — specifies the height of the input image in scanlines (default is 512). yes, scanlines, not pixels — that's the unit for height here, noted and respected. 💀
• -S out_squaresize — sets both the width and height of the extracted output rectangle to out_squaresize in pixels. the shortcut for when you want a cute square crop. 🎀
• -W out_width — specifies the width of the extracted output rectangle in pixels.
• -N out_height — specifies the height of the extracted output rectangle in scanlines.
• -x xorig — specifies the x-coordinate of the origin for the extraction (default is 0).
• -y yorig — specifies the y-coordinate of the origin for the extraction (default is 0). heads up: the origin corresponds to the lower-left corner. so y grows upward, okurrr. 🌈
• -o out_file.bw — specifies the name of the output file. and listen: if standard output is also redirected or piped, bwrect writes the same output to both destinations. double the output, double the fun, no cap. if -o isn't provided, output is written to standard output. 💜

🦋 EXAMPLES 🦋

Example 1. Extracting a 256x256 rectangle from a 1024x1024 image

$ bwrect -s 1024 -S 256 -x 0 -y 0 in.bw > out.bw

this command extracts a 256x256 rectangle from the lower-left corner of the 1024x1024 image in.bw and writes it to out.bw using standard output redirection. ate and left no crumbs. 🔥

Example 2. Extracting a 100x100 region with a specific origin and output file

$ bwrect -W 100 -N 100 -x 200 -y 200 -o out.bw in.bw

this command extracts a 100x100 rectangle starting at coordinate (200, 200) from an image of default size (512x512) and saves it directly to out.bw using the -o option. chef's kiss. 🍓

⭐ SEE ALSO ⭐

brlcad(1), bwcrop(1), bwscale(1), pixrect(1), bw(5) — go read the whole squad, iykyk. 💫

👑 AUTHOR 👑

BRL-CAD Team — legends, honestly. 🫡

💅 COPYRIGHT 💅

This software is Copyright (c) 1989-2026 by the United States Government as represented by U.S. Army Research Laboratory. periodt. ⭐

🙈 BUG REPORTS 🙈

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org. don't be shy, they're nice, i promise. 💌

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okay that's the whole page bestie, go crop some rectangles and be iconic. this beauty comes to you courtesy of BRL-CAD — the BWRECT(1) page, sitting pretty in the BRL-CAD manual set, with that copyright window running 1989-2026. mwah, love u, bye! 💖🧚✨