2nd/10_Wiki/Topics/Frontend/에일리어싱 (Aliasing).md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-에일리어싱-aliasing	에일리어싱 (Aliasing)	10_Wiki/Topics	verified	self	Aliasing 계단현상 Jaggies	none	A	0.9	applied	graphics rendering frontend antialiasing		2026-05-10	pending	language framework CSS/JS Canvas/WebGL

에일리어싱 (Aliasing)

매 한 줄

"매 sampling rate 가 signal frequency 의 절반 미만일 때 발생하는 distortion". Nyquist theorem 위반 의 결과로, frontend 에서 매 jagged edges, moiré patterns, shimmer 형태로 나타남. 매 antialiasing (AA) 기법으로 완화.

매 핵심

매 정의

• Spatial aliasing: 매 jagged edges (계단 현상) — pixel grid 가 매 diagonal/curved line 의 표현 부족.
• Temporal aliasing: 매 frame rate 부족 의 결과 — wagon-wheel effect, stutter.
• Texture aliasing: 매 minification 시 매 moiré pattern.

매 원인

• Discrete sampling: 매 continuous signal 을 discrete pixel 로 sampling.
• Sub-pixel detail: 매 single pixel 보다 작은 detail 의 미손실 표현 불가.
• Nyquist criterion: 매 sampling_rate ≥ 2 × max_frequency 충족 X.

매 응용 (frontend)

1. Canvas/WebGL rendering: 매 line, polygon, font 의 smooth rendering.
2. CSS transforms: 매 rotated/scaled element 의 edge.
3. SVG icons: 매 small size 매 shimmer 방지.

💻 패턴

Canvas 2D antialiasing 활성화

const canvas = document.querySelector('canvas');
const ctx = canvas.getContext('2d');

// imageSmoothingEnabled: 매 default true
ctx.imageSmoothingEnabled = true;
ctx.imageSmoothingQuality = 'high'; // 'low' | 'medium' | 'high'

ctx.drawImage(img, 0, 0, 100, 100);

WebGL MSAA (Multi-Sample Anti-Aliasing)

const gl = canvas.getContext('webgl2', {
  antialias: true, // 매 MSAA 활성화 (browser 가 sample count 결정)
});

// 매 explicit sample count (offscreen framebuffer)
const fb = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
const rb = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, rb);
gl.renderbufferStorageMultisample(
  gl.RENDERBUFFER, 4, gl.RGBA8, width, height
);

CSS — 매 transform 시 jagged edge 완화

.rotated {
  transform: rotate(15deg);
  /* 매 GPU 가속 + subpixel AA */
  will-change: transform;
  backface-visibility: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 매 image scaling 시 quality */
img {
  image-rendering: auto; /* 매 default — browser AA */
  /* image-rendering: pixelated; — 매 retro pixel art */
  /* image-rendering: crisp-edges; — 매 sharp without AA */
}

SVG — 매 sub-pixel rendering

<!-- 매 매끈한 line: shape-rendering -->
<svg viewBox="0 0 100 100">
  <line
    x1="10" y1="10" x2="90" y2="50"
    stroke="black"
    shape-rendering="geometricPrecision"
  />
  <!-- "geometricPrecision" | "crispEdges" | "auto" -->
</svg>

Three.js — 매 FXAA postprocessing

import * as THREE from 'three';
import { EffectComposer } from 'three/addons/postprocessing/EffectComposer.js';
import { ShaderPass } from 'three/addons/postprocessing/ShaderPass.js';
import { FXAAShader } from 'three/addons/shaders/FXAAShader.js';

const composer = new EffectComposer(renderer);
const fxaa = new ShaderPass(FXAAShader);
fxaa.material.uniforms.resolution.value.set(
  1 / window.innerWidth, 1 / window.innerHeight
);
composer.addPass(fxaa);

Devicepixelratio 보정

function setupHiDPICanvas(canvas) {
  const dpr = window.devicePixelRatio || 1;
  const rect = canvas.getBoundingClientRect();

  canvas.width = rect.width * dpr;
  canvas.height = rect.height * dpr;
  canvas.style.width = `${rect.width}px`;
  canvas.style.height = `${rect.height}px`;

  const ctx = canvas.getContext('2d');
  ctx.scale(dpr, dpr);
  return ctx;
}

매 결정 기준

상황	Approach
매 SVG icon, vector	shape-rendering="geometricPrecision"
매 retina display	devicePixelRatio scaling
매 WebGL game	MSAA 4x or FXAA postprocess
매 pixel art	image-rendering: pixelated (AA 끄기)
매 rotated text	-webkit-font-smoothing: antialiased

기본값: 매 antialias: true 활성화 + DPR scaling 적용.

🔗 Graph

• 부모: Computer Graphics
• 변형: FXAA
• 응용: WebGL · SVG

🤖 LLM 활용

언제: 매 Canvas/WebGL rendering 매 jagged edge 의 완화, retina display 의 sharp output. 언제 X: 매 pixel art (의도적 jagged), 매 ultra low-end GPU (AA 비용 부담).

❌ 안티패턴

• DPR 무시: 매 retina 매 blurry — devicePixelRatio scaling 누락.
• AA 항상 max: 매 mobile GPU 매 fps 저하 — adaptive quality 필요.
• transform 후 sub-pixel position: 매 0.5px offset 매 blur — translateZ(0) hack.

🧪 검증 / 중복

• Verified (MDN Canvas API, WebGL spec, Three.js docs).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — aliasing, AA techniques (MSAA/FXAA), Canvas/WebGL/SVG/CSS 패턴 정리