Cutter

Jan 2026 · age 44

What it was

A sprite-sheet cutter for an asset pipeline, in Java 21 and JavaFX. Load one image, draw named rectangles over it, and let pixel heuristics tighten or grow each rectangle to fit the art: peel an edge while its row or column is uniform, by average or by matching the first pixel, until nothing changes. Other commands centred a box on the dark pixels, or on everything that was not white. All of it ran in premultiplied-alpha colour, so "white" meant the same thing for opaque and half-transparent pixels. At high zoom a viewport-sized canvas drew only the visible pixels as big squares. Rectangles travelled as a sidecar file beside the image and as plain text through the clipboard, and export wrote each one as a PNG. About 2,350 lines, nearly all in one controller, published in one January morning; the licence says 2024, so the code is likely older.

Wins, for the age

• At forty-four, Jeff picked the colour space before writing the heuristic. Defining white relative to alpha made transparency and whiteness a single test.
• Two families of edge detection, one tolerant of gradients and one strict, each iterated to a fixpoint. Found on their own what TexturePacker's auto-trim had already found.
• Clipboard interop as x,y,w,h,name text, so rectangles could be pasted into a spreadsheet or another running copy.
• A working, packaged single-jar tool that did its job for a real pipeline, and whose behaviour was clear enough to be extracted as a specification and rebuilt faithfully elsewhere.

What it taught

• Choose the colour space first, then the heuristic.
• Fixpoint edge peeling is enough for sprite sheets. The simple thing, run until it stops moving, is often the whole answer.
• Do not commit personal settings. The first commit carried the author's own recent-files list.
• A README is a promise: this one claimed an auto-save that never existed, and told readers to run tests that were never written. Even a primate working alongside an agent has to read the docs they ship.

Genealogy

Ancestors: Pixel Master: pixel-level tools for art that lives in a grid. Tiles: slicing art into game-ready pieces by rule. Descendants: RPG Spine: the one-bit image pipeline for a handheld RPG.

Epitaph

It found the edges of sprites by asking, in premultiplied alpha, whether a row was all the same, and saved its answers beside the picture. Its README promised an auto-save it never had.