#!/usr/bin/env node
/* locate.mjs — find "X" in an image WITHOUT any detector API or key.
*
* You (the author model) are weak at regressing pixel coordinates but strong at
* "which numbered strip is the target in?" — so localization = RSVP grid-index
* (ACL 2025 long.715): pick strips on a numbered grid, reconstruct the box
* geometrically. Zero npm deps — node + ffmpeg (both already required by
* hyperframes). Full protocol: grounding/PROTOCOL.md.
*
* THE LOOP (you read images between steps):
* 1) node locate.mjs overlay
--out DIR
* → DIR/gv.png (vertical strips 1..9) + DIR/gh.png (horizontal 1..9).
* READ both, pick the strip numbers the target spans.
* 2) node locate.mjs region
--vids 4,5 --hids 6,7 --out DIR
* → prints coarse region + writes DIR/gc.png (region cropped+upscaled,
* finer 6×6 grid). READ it, pick the finer strips.
* 3) node locate.mjs final
--region x0,y0,x1,y1 --vids 3,4 --hids 3,4
* → {box, center} normalized to the FULL image.
* 4) node locate.mjs mark
--box x0,y0,x1,y1 --out DIR/check.png
* → VERIFY: read check.png — is the red box on the target? If off,
* redo step 2/3 with corrected strips. Never skip this.
*/
import { execFileSync } from "node:child_process";
import { existsSync, mkdirSync, copyFileSync } from "node:fs";
const N1 = 9,
PAD1 = 0.4; // stage 1: strips per axis, padding in STRIP units
const N2 = 6,
PAD2 = 0.25; // stage 2 (crop)
const GREEN = "0x3CDC5A",
BLUE = "0x3C82FF",
RED = "0xFF3232";
const ff = (args) =>
execFileSync("ffmpeg", ["-v", "error", "-y", ...args], {
stdio: ["ignore", "ignore", "inherit"],
});
function probe(img) {
const out = execFileSync("ffprobe", [
"-v",
"error",
"-select_streams",
"v:0",
"-show_entries",
"stream=width,height",
"-of",
"csv=p=0",
img,
])
.toString()
.trim();
const [w, h] = out.split(",").map(Number);
return { w, h };
}
function font() {
const dst = "/tmp/locate-font.ttf";
if (!existsSync(dst)) {
for (const c of [
"/System/Library/Fonts/Supplemental/Arial Bold.ttf",
"/System/Library/Fonts/Supplemental/Arial.ttf",
"/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
]) {
if (existsSync(c)) {
copyFileSync(c, dst);
break;
}
}
}
return dst;
}
function gridFilters(w, h, n, axis, fz) {
const F = font(),
fs = [];
if (axis === "v" || axis === "both") {
for (let i = 1; i < n; i++)
fs.push(`drawbox=x=${Math.round((i * w) / n)}:y=0:w=2:h=${h}:color=${GREEN}@0.8:t=fill`);
for (let i = 0; i < n; i++)
fs.push(
`drawtext=fontfile=${F}:text='${i + 1}':x=${Math.round(((i + 0.5) * w) / n - fz * 0.3)}:y=6:fontsize=${fz}:fontcolor=black:box=1:boxcolor=white@0.95:boxborderw=5`,
);
}
if (axis === "h" || axis === "both") {
for (let j = 1; j < n; j++)
fs.push(`drawbox=x=0:y=${Math.round((j * h) / n)}:w=${w}:h=2:color=${BLUE}@0.8:t=fill`);
for (let j = 0; j < n; j++)
fs.push(
`drawtext=fontfile=${F}:text='${j + 1}':x=6:y=${Math.round(((j + 0.5) * h) / n - fz * 0.5)}:fontsize=${fz}:fontcolor=black:box=1:boxcolor=white@0.95:boxborderw=5`,
);
}
return fs;
}
const ids = (s) => String(s).split(",").filter(Boolean).map(Number);
const regionOf = (v, h, n, pad) => [
Math.max(Math.min(...v) - 1 - pad, 0) / n,
Math.max(Math.min(...h) - 1 - pad, 0) / n,
Math.min(Math.max(...v) + pad, n) / n,
Math.min(Math.max(...h) + pad, n) / n,
];
const r4 = (x) => Math.round(x * 1e4) / 1e4;
const out = (o) => console.log(JSON.stringify(o));
// --- tiny arg parsing: locate.mjs
--k v ---
const [cmd, ...rest] = process.argv.slice(2);
const pos = rest.filter((a) => !a.startsWith("--"));
const opt = {};
for (let i = 0; i < rest.length; i++)
if (rest[i].startsWith("--")) opt[rest[i].slice(2)] = rest[i + 1];
const img = pos[0];
if (cmd === "overlay") {
const dir = opt.out || ".";
mkdirSync(dir, { recursive: true });
const n = Number(opt.n || N1);
const { w, h } = probe(img);
const fz = Math.max(16, Math.round(Math.min(w, h) / 22));
ff(["-i", img, "-vf", gridFilters(w, h, n, "v", fz).join(","), `${dir}/gv.png`]);
ff(["-i", img, "-vf", gridFilters(w, h, n, "h", fz).join(","), `${dir}/gh.png`]);
out({
w,
h,
n,
vertical: `${dir}/gv.png`,
horizontal: `${dir}/gh.png`,
next: "READ gv.png + gh.png, then: locate.mjs region
--vids .. --hids .. --out " + dir,
});
} else if (cmd === "region") {
const dir = opt.out || ".";
mkdirSync(dir, { recursive: true });
const n = Number(opt.n || N1),
nf = Number(opt.nf || N2);
const reg = regionOf(ids(opt.vids), ids(opt.hids), n, PAD1);
const { w, h } = probe(img);
const cx = Math.floor(reg[0] * w),
cy = Math.floor(reg[1] * h);
const cw = Math.max(2, Math.floor((reg[2] - reg[0]) * w)),
ch = Math.max(2, Math.floor((reg[3] - reg[1]) * h));
const uw = Math.max(cw, 640),
uh = Math.round((ch * uw) / cw);
const fz = Math.max(15, Math.round(Math.min(uw, uh) / 16));
ff([
"-i",
img,
"-vf",
[
`crop=${cw}:${ch}:${cx}:${cy}`,
`scale=${uw}:${uh}`,
...gridFilters(uw, uh, nf, "both", fz),
].join(","),
`${dir}/gc.png`,
]);
out({
region: reg.map(r4),
crop_grid: `${dir}/gc.png`,
nf,
next: `READ gc.png, then: locate.mjs final
--region ${reg.map(r4).join(",")} --vids .. --hids ..`,
});
} else if (cmd === "final") {
const nf = Number(opt.nf || N2);
const reg = opt.region.split(",").map(Number);
const rl = regionOf(ids(opt.vids), ids(opt.hids), nf, PAD2);
const [x0, y0, x1, y1] = reg;
const box = [
x0 + rl[0] * (x1 - x0),
y0 + rl[1] * (y1 - y0),
x0 + rl[2] * (x1 - x0),
y0 + rl[3] * (y1 - y0),
].map(r4);
out({
box,
center: [r4((box[0] + box[2]) / 2), r4((box[1] + box[3]) / 2)],
next:
"VERIFY: locate.mjs mark
--box " +
box.join(",") +
" --out /check.png — then READ it",
});
} else if (cmd === "mark") {
const box = opt.box.split(",").map(Number);
const { w, h } = probe(img);
const bx = Math.round(box[0] * w),
by = Math.round(box[1] * h);
const bw = Math.max(2, Math.round((box[2] - box[0]) * w)),
bh = Math.max(2, Math.round((box[3] - box[1]) * h));
const dst = opt.out || "./check.png";
ff(["-i", img, "-vf", `drawbox=x=${bx}:y=${by}:w=${bw}:h=${bh}:color=${RED}@1:t=6`, dst]);
out({
marked: dst,
next: "READ it — red box on the target? If off, redo region/final with corrected strips.",
});
} else if (cmd === "auto") {
// OPTIONAL fast path — only if a strong detector key happens to exist. Never assume it.
const key = process.env.GEMINI_API_KEY;
if (!key) {
console.error(
"auto needs GEMINI_API_KEY; use the grid loop instead (overlay→region→final→mark)",
);
process.exit(1);
}
const target = pos[1];
const b64 = execFileSync("base64", ["-i", img]).toString().replace(/\n/g, "");
const mime = img.match(/\.png$/i) ? "image/png" : "image/jpeg";
const body = {
contents: [
{
parts: [
{ inline_data: { mime_type: mime, data: b64 } },
{
text: `Detect "${target}". Return ONLY {"box_2d":[ymin,xmin,ymax,xmax]} integers 0-1000.`,
},
],
},
],
generationConfig: { temperature: 0, response_mime_type: "application/json" },
};
const res = await fetch(
`https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent?key=${key}`,
{ method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify(body) },
);
const t = (await res.json()).candidates[0].content.parts[0].text;
let bb = JSON.parse(t.match(/\{[\s\S]*\}/)[0]).box_2d;
if (Array.isArray(bb[0])) bb = bb[0];
const s = Math.max(...bb) > 1.5 ? 1000 : 1;
const box = [bb[1] / s, bb[0] / s, bb[3] / s, bb[2] / s].map(r4);
out({ box, center: [r4((box[0] + box[2]) / 2), r4((box[1] + box[3]) / 2)] });
} else {
console.error("usage: locate.mjs overlay|region|final|mark|auto … (see header comment)");
process.exit(1);
}