diff --git a/web/src/lib/core/alpha.test.ts b/web/src/lib/core/alpha.test.ts
index 783a1f6..5a91335 100644
--- a/web/src/lib/core/alpha.test.ts
+++ b/web/src/lib/core/alpha.test.ts
@@ -3,6 +3,7 @@ import {
 	colorMask,
 	extractAlphaMask,
 	flattenOntoColor,
+	hardenAlpha,
 	invertAlpha,
 	parseHex,
 	removeColorToAlpha,
@@ -11,6 +12,22 @@ import {
 } from './alpha';
 import { makeImage } from './test-helpers';
 
+describe('hardenAlpha', () => {
+	it('бинаризует альфу по порогу, RGB не трогает', () => {
+		const out = hardenAlpha(
+			makeImage(2, 1, [
+				[10, 20, 30, 100],
+				[40, 50, 60, 200]
+			]),
+			50
+		);
+		expect([...out.data]).toEqual([
+			10, 20, 30, 0,
+			40, 50, 60, 255
+		]);
+	});
+});
+
 describe('setAlphaChannel', () => {
 	it('задаёт константную альфу', () => {
 		const out = setAlphaChannel(makeImage(2, 1, [
diff --git a/web/src/lib/core/alpha.ts b/web/src/lib/core/alpha.ts
index c554ed6..9f29c99 100644
--- a/web/src/lib/core/alpha.ts
+++ b/web/src/lib/core/alpha.ts
@@ -73,6 +73,18 @@ export function invertAlpha(img: PixelImage): PixelImage {
 	return out;
 }
 
+export function hardenAlpha(img: PixelImage, thresholdPercent: number): PixelImage {
+	const threshold = (clamp(thresholdPercent, 0, 100) / 100) * 255;
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < out.data.length; i += 4) {
+		out.data[i] = img.data[i];
+		out.data[i + 1] = img.data[i + 1];
+		out.data[i + 2] = img.data[i + 2];
+		out.data[i + 3] = img.data[i + 3] >= threshold ? 255 : 0;
+	}
+	return out;
+}
+
 export function colorMask(img: PixelImage, hex: string, tolerancePercent = 0): PixelImage {
 	const [targetR, targetG, targetB] = parseHex(hex);
 	const tolerance = (clamp(tolerancePercent, 0, 100) / 100) * MAX_COLOR_DISTANCE;
diff --git a/web/src/lib/core/morphology.test.ts b/web/src/lib/core/morphology.test.ts
new file mode 100644
index 0000000..8dc2521
--- /dev/null
+++ b/web/src/lib/core/morphology.test.ts
@@ -0,0 +1,168 @@
+import { describe, expect, it } from 'vitest';
+import {
+	buildAlphaMask,
+	closingImage,
+	contourImage,
+	dilateImage,
+	dilateMask,
+	erodeImage,
+	erodeMask,
+	openingImage,
+	strokeImage
+} from './morphology';
+import { makeImage } from './test-helpers';
+
+function maskFrom(rows: string[]): Uint8Array {
+	const flat = rows.join('');
+	const mask = new Uint8Array(flat.length);
+	for (let i = 0; i < flat.length; i++) {
+		mask[i] = flat[i] === '#' ? 1 : 0;
+	}
+	return mask;
+}
+
+function toRows(mask: Uint8Array, w: number): string[] {
+	const rows: string[] = [];
+	for (let y = 0; y < mask.length / w; y++) {
+		let row = '';
+		for (let x = 0; x < w; x++) {
+			row += mask[y * w + x] === 1 ? '#' : '.';
+		}
+		rows.push(row);
+	}
+	return rows;
+}
+
+describe('dilateMask', () => {
+	it('одиночный пиксель r=1 превращается в плюс', () => {
+		const out = dilateMask(
+			maskFrom(['.....', '.....', '..#..', '.....', '.....']),
+			5,
+			5,
+			1
+		);
+		expect(toRows(out, 5)).toEqual(['.....', '..#..', '.###.', '..#..', '.....']);
+	});
+
+	it('r=2 даёт ромб радиуса 2', () => {
+		const out = dilateMask(
+			maskFrom(['.....', '.....', '..#..', '.....', '.....']),
+			5,
+			5,
+			2
+		);
+		expect(toRows(out, 5)).toEqual(['..#..', '.###.', '#####', '.###.', '..#..']);
+	});
+});
+
+describe('erodeMask', () => {
+	it('сплошной объект во весь кадр не сжимается от границ', () => {
+		const solid = maskFrom(['#####', '#####', '#####', '#####', '#####']);
+		expect([...erodeMask(solid, 5, 5, 1)]).toEqual([...solid]);
+	});
+
+	it('изолированный пиксель исчезает', () => {
+		const out = erodeMask(
+			maskFrom(['.....', '.....', '..#..', '.....', '.....']),
+			5,
+			5,
+			1
+		);
+		expect([...out].every((v) => v === 0)).toBe(true);
+	});
+});
+
+describe('opening/closing образы', () => {
+	it('opening убирает отстоящий мусорный пиксель и сохраняет блок', () => {
+		const B = [10, 10, 10, 255];
+		const T = [0, 0, 0, 0];
+		const S = [200, 200, 200, 255];
+		const out = openingImage(
+			makeImage(
+				6,
+				3,
+				[B, B, B, T, S, T, B, B, B, T, T, T, B, B, B, T, T, T]
+			),
+			1
+		);
+		const at = (x: number, y: number) => out.data[(y * 6 + x) * 4 + 3];
+		expect(at(0, 1)).toBe(255);
+		expect(at(2, 1)).toBe(255);
+		expect(at(4, 1)).toBe(0);
+	});
+
+	it('closing заполняет одиночную прозрачную дыру чёрным', () => {
+		const pixels: number[][] = [];
+		for (let y = 0; y < 3; y++) {
+			for (let x = 0; x < 3; x++) {
+				pixels.push(x === 1 && y === 1 ? [0, 0, 0, 0] : [255, 255, 255, 255]);
+			}
+		}
+		const out = closingImage(makeImage(3, 3, pixels), 1);
+		const di = (1 * 3 + 1) * 4;
+		expect(out.data[di + 3]).toBe(255);
+	});
+});
+
+describe('image-обёртки', () => {
+	it('dilateImage сохраняет RGB содержимого, новые пиксели непрозрачны', () => {
+		const T = [0, 0, 0, 0];
+		const O = [200, 50, 25, 255];
+		const img = makeImage(5, 2, [T, O, T, T, T, T, T, T, T, T]);
+		const out = dilateImage(img, 1);
+		const at = (x: number, y: number) => {
+			const di = (y * 5 + x) * 4;
+			return [out.data[di], out.data[di + 1], out.data[di + 2], out.data[di + 3]];
+		};
+		expect(at(1, 0)).toEqual([200, 50, 25, 255]);
+		expect(at(0, 0)).toEqual([0, 0, 0, 255]);
+		expect(at(4, 0)[3]).toBe(0);
+	});
+
+	it('erodeImage не стирает объект у края кадра', () => {
+		const img = makeImage(2, 2, [
+			[10, 20, 30, 255],
+			[10, 20, 30, 255],
+			[10, 20, 30, 255],
+			[10, 20, 30, 255]
+		]);
+		const out = erodeImage(img, 1);
+		for (let i = 0; i < out.data.length; i += 4) {
+			expect(out.data[i + 3]).toBe(255);
+		}
+	});
+});
+
+describe('strokeImage', () => {
+	it('кольцо цвета обводки вокруг квадрата', () => {
+		const pixels: number[][] = [];
+		for (let y = 0; y < 7; y++) {
+			for (let x = 0; x < 7; x++) {
+				pixels.push(x >= 2 && x <= 4 && y >= 2 && y <= 4 ? [255, 0, 0, 255] : [0, 0, 0, 0]);
+			}
+		}
+		const out = strokeImage(makeImage(7, 7, pixels), 1, '#0000ff');
+		const at = (x: number, y: number) =>
+			[...out.data.slice((y * 7 + x) * 4, (y * 7 + x) * 4 + 4)];
+		expect(at(2, 3)).toEqual([255, 0, 0, 255]);
+		expect(at(1, 3)).toEqual([0, 0, 255, 255]);
+		expect(at(0, 0)).toEqual([0, 0, 0, 0]);
+	});
+});
+
+describe('contourImage', () => {
+	it('линия по краю квадрата, центр прозрачен', () => {
+		const pixels: number[][] = [];
+		for (let y = 0; y < 7; y++) {
+			for (let x = 0; x < 7; x++) {
+				pixels.push(x >= 2 && x <= 4 && y >= 2 && y <= 4 ? [255, 0, 0, 255] : [0, 0, 0, 0]);
+			}
+		}
+		const out = contourImage(makeImage(7, 7, pixels), 1, '#0000ff');
+		const at = (x: number, y: number) =>
+			[...out.data.slice((y * 7 + x) * 4, (y * 7 + x) * 4 + 4)];
+		expect(at(2, 2)).toEqual([0, 0, 255, 255]);
+		expect(at(3, 3)).toEqual([0, 0, 0, 0]);
+		expect(at(1, 3)).toEqual([0, 0, 0, 0]);
+	});
+});
diff --git a/web/src/lib/core/morphology.ts b/web/src/lib/core/morphology.ts
new file mode 100644
index 0000000..dcdbc0b
--- /dev/null
+++ b/web/src/lib/core/morphology.ts
@@ -0,0 +1,192 @@
+import { parseHex } from './alpha';
+import { clonePixelImage, createPixelImage, type PixelImage } from './types';
+
+type Mask = Uint8Array;
+
+type Offset = { dx: number; dy: number };
+
+function discOffsets(radius: number): Offset[] {
+	const offsets: Offset[] = [];
+	for (let dy = -radius; dy <= radius; dy++) {
+		for (let dx = -radius; dx <= radius; dx++) {
+			if (dx * dx + dy * dy <= radius * radius) {
+				offsets.push({ dx, dy });
+			}
+		}
+	}
+	return offsets;
+}
+
+export function buildAlphaMask(img: PixelImage): Mask {
+	const mask = new Uint8Array(img.width * img.height);
+	for (let i = 0; i < mask.length; i++) {
+		mask[i] = img.data[i * 4 + 3] > 0 ? 1 : 0;
+	}
+	return mask;
+}
+
+export function dilateMask(mask: Mask, width: number, height: number, radius: number): Mask {
+	const r = Math.trunc(radius);
+	if (r < 1) return mask.slice();
+	const out = new Uint8Array(mask.length);
+	const offsets = discOffsets(r);
+	for (let y = 0; y < height; y++) {
+		for (let x = 0; x < width; x++) {
+			let hit = 0;
+			for (const { dx, dy } of offsets) {
+				const sx = x + dx;
+				const sy = y + dy;
+				if (sx < 0 || sy < 0 || sx >= width || sy >= height) continue;
+				if (mask[sy * width + sx] === 1) {
+					hit = 1;
+					break;
+				}
+			}
+			out[y * width + x] = hit;
+		}
+	}
+	return out;
+}
+
+export function erodeMask(mask: Mask, width: number, height: number, radius: number): Mask {
+	const r = Math.trunc(radius);
+	if (r < 1) return mask.slice();
+	const out = new Uint8Array(mask.length);
+	const offsets = discOffsets(r);
+	for (let y = 0; y < height; y++) {
+		for (let x = 0; x < width; x++) {
+			let solid = 1;
+			for (const { dx, dy } of offsets) {
+				const sx = x + dx;
+				const sy = y + dy;
+				if (sx < 0 || sy < 0 || sx >= width || sy >= height) continue;
+				if (mask[sy * width + sx] !== 1) {
+					solid = 0;
+					break;
+				}
+			}
+			out[y * width + x] = solid;
+		}
+	}
+	return out;
+}
+
+export function applyMaskAlpha(img: PixelImage, mask: Mask): PixelImage {
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < mask.length; i++) {
+		const di = i * 4;
+		if (mask[i] === 1) {
+			out.data[di] = img.data[di];
+			out.data[di + 1] = img.data[di + 1];
+			out.data[di + 2] = img.data[di + 2];
+			out.data[di + 3] = 255;
+		} else {
+			out.data[di + 3] = 0;
+		}
+	}
+	return out;
+}
+
+export function dilateImage(img: PixelImage, radiusPx: number): PixelImage {
+	if (radiusPx < 1) return clonePixelImage(img);
+	return applyMaskAlpha(img, dilateMask(buildAlphaMask(img), img.width, img.height, radiusPx));
+}
+
+export function erodeImage(img: PixelImage, radiusPx: number): PixelImage {
+	if (radiusPx < 1) return clonePixelImage(img);
+	return applyMaskAlpha(img, erodeMask(buildAlphaMask(img), img.width, img.height, radiusPx));
+}
+
+export function strokeImage(
+	img: PixelImage,
+	radiusPx: number,
+	colorHex: string
+): PixelImage {
+	const r = Math.trunc(radiusPx);
+	if (r < 1) return clonePixelImage(img);
+	const [cr, cg, cb] = parseHex(colorHex);
+	const mask = buildAlphaMask(img);
+	const ring = dilateMask(mask, img.width, img.height, r);
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < ring.length; i++) {
+		const di = i * 4;
+		if (ring[i] === 1 && mask[i] === 0) {
+			out.data[di] = cr;
+			out.data[di + 1] = cg;
+			out.data[di + 2] = cb;
+			out.data[di + 3] = 255;
+		} else if (mask[i] === 1) {
+			out.data[di] = img.data[di];
+			out.data[di + 1] = img.data[di + 1];
+			out.data[di + 2] = img.data[di + 2];
+			out.data[di + 3] = img.data[di + 3];
+		}
+	}
+	return out;
+}
+
+export function contourImage(img: PixelImage, radiusPx: number, colorHex: string): PixelImage {
+	const r = Math.max(1, Math.trunc(radiusPx));
+	const [cr, cg, cb] = parseHex(colorHex);
+	const mask = buildAlphaMask(img);
+	const inner = erodeMask(mask, img.width, img.height, r);
+	const line = new Uint8Array(mask.length);
+	for (let i = 0; i < mask.length; i++) {
+		line[i] = mask[i] === 1 && inner[i] === 0 ? 1 : 0;
+	}
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < line.length; i++) {
+		const di = i * 4;
+		if (line[i] === 1) {
+			out.data[di] = cr;
+			out.data[di + 1] = cg;
+			out.data[di + 2] = cb;
+			out.data[di + 3] = 255;
+		}
+	}
+	return out;
+}
+
+export function openingMask(mask: Mask, w: number, h: number, radius: number): Mask {
+	return dilateMask(erodeMask(mask, w, h, radius), w, h, radius);
+}
+
+export function closingMask(mask: Mask, w: number, h: number, radius: number): Mask {
+	return erodeMask(dilateMask(mask, w, h, radius), w, h, radius);
+}
+
+export function openingImage(img: PixelImage, radiusPx: number): PixelImage {
+	if (radiusPx < 1) return clonePixelImage(img);
+	const mask = buildAlphaMask(img);
+	const opened = openingMask(mask, img.width, img.height, radiusPx);
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < opened.length; i++) {
+		const di = i * 4;
+		out.data[di] = img.data[di];
+		out.data[di + 1] = img.data[di + 1];
+		out.data[di + 2] = img.data[di + 2];
+		out.data[di + 3] = opened[i] === 1 ? img.data[di + 3] : 0;
+	}
+	return out;
+}
+
+export function closingImage(img: PixelImage, radiusPx: number): PixelImage {
+	if (radiusPx < 1) return clonePixelImage(img);
+	const mask = buildAlphaMask(img);
+	const closed = closingMask(mask, img.width, img.height, radiusPx);
+	const out = createPixelImage(img.width, img.height);
+	for (let i = 0; i < closed.length; i++) {
+		const di = i * 4;
+		if (closed[i] === 1 && mask[i] === 0) {
+			out.data[di] = 0;
+			out.data[di + 1] = 0;
+			out.data[di + 2] = 0;
+		} else {
+			out.data[di] = img.data[di];
+			out.data[di + 1] = img.data[di + 1];
+			out.data[di + 2] = img.data[di + 2];
+		}
+		out.data[di + 3] = closed[i] === 1 ? 255 : img.data[di + 3];
+	}
+	return out;
+}