diff --git a/src/renderer/components/MosaicView.tsx b/src/renderer/components/MosaicView.tsx
index dd6445c..f8f254a 100644
--- a/src/renderer/components/MosaicView.tsx
+++ b/src/renderer/components/MosaicView.tsx
@@ -1,8 +1,9 @@
 import { useCallback, useEffect, useRef, useState } from 'react'
-import { thumbUrl, baseName } from '../media'
+import { thumbUrl, mediaUrl, baseName } from '../media'
 import type { IndexedAsset } from '@shared/types'
 
-type Tile = { img: HTMLImageElement; r: number; g: number; b: number }
+type Tile = { img: HTMLImageElement; asset: IndexedAsset; r: number; g: number; b: number }
+type GridMap = { cols: number; rows: number; cellPx: number; map: (Tile | null)[] }
 
 /** crossOrigin 이미지를 로드 (캔버스 픽셀 읽기용). 실패 시 null */
 function loadImage(src: string): Promise<HTMLImageElement | null> {
@@ -29,6 +30,7 @@ function averageColor(img: HTMLImageElement): { r: number; g: number; b: number
 /**
  * 포토모자이크 뷰어 — 대표(대상) 사진을 라이브러리 사진(타일)들로 재구성한다.
  * 대상 이미지를 격자로 나눠 각 칸의 평균색과 가장 가까운 타일을 배치.
+ * 격자선으로 타일 경계를 보이게 하고, 타일을 클릭하면 그 원본 사진을 띄운다.
  */
 export function MosaicView(props: {
   target: IndexedAsset
@@ -40,10 +42,14 @@ export function MosaicView(props: {
   const canvasRef = useRef<HTMLCanvasElement>(null)
   const poolRef = useRef<Tile[]>([])
   const targetImgRef = useRef<HTMLImageElement | null>(null)
+  const gridRef = useRef<GridMap>({ cols: 0, rows: 0, cellPx: 0, map: [] })
   const [ready, setReady] = useState(false)
-  const [cols, setCols] = useState(96)
-  const [blend, setBlend] = useState(0.35)
+  // 기본값을 낮춰(타일이 커서 사진이 보임) 모자이크 느낌이 나도록. 더 잘게는 슬라이더로.
+  const [cols, setCols] = useState(48)
+  const [blend, setBlend] = useState(0.25)
   const [unique, setUnique] = useState(true)
+  const [grid, setGrid] = useState(true)
+  const [picked, setPicked] = useState<IndexedAsset | null>(null)
 
   // 타일/대상 이미지 로드 + 평균색 사전 계산 (1회)
   useEffect(() => {
@@ -52,14 +58,14 @@ export function MosaicView(props: {
     void (async () => {
       const pool: Tile[] = []
       const imgs = await Promise.all(tiles.map((a) => loadImage(thumbUrl(a.contentHash))))
-      for (const img of imgs) {
-        if (!img) continue
+      imgs.forEach((img, i) => {
+        if (!img) return
         try {
-          pool.push({ img, ...averageColor(img) })
+          pool.push({ img, asset: tiles[i], ...averageColor(img) })
         } catch {
           /* 손상 타일 무시 */
         }
-      }
+      })
       const tImg = await loadImage(thumbUrl(target.contentHash))
       if (cancelled) return
       poolRef.current = pool
@@ -89,12 +95,19 @@ export function MosaicView(props: {
     sctx.drawImage(tImg, 0, 0, gridCols, gridRows)
     const cells = sctx.getImageData(0, 0, gridCols, gridRows).data
 
-    // 출력 캔버스 상한 3600px → 해상도(열 수)를 높여도 타일이 뭉개지지 않고 고해상도로 저장
+    // 출력 캔버스 상한 3600px → 해상도를 높여도 타일이 뭉개지지 않고 고해상도로 저장
     const cellPx = Math.max(8, Math.round(3600 / gridCols))
     canvas.width = gridCols * cellPx
     canvas.height = gridRows * cellPx
     const ctx = canvas.getContext('2d')!
+    // 격자선 두께: 타일이 클수록 살짝 두껍게(보이게), 작을수록 얇게
+    const gap = grid ? Math.max(1, Math.round(cellPx * 0.06)) : 0
+    if (gap > 0) {
+      ctx.fillStyle = '#0c0c0d' // 타일 사이 '그라우트'(어두운 줄눈)
+      ctx.fillRect(0, 0, canvas.width, canvas.height)
+    }
 
+    const map: (Tile | null)[] = new Array(gridCols * gridRows).fill(null)
     // 최근 사용 타일에 페널티를 주어 같은 타일이 뭉치는 것을 줄임
     const recent = new Map<Tile, number>()
     let step = 0
@@ -124,31 +137,51 @@ export function MosaicView(props: {
           }
         }
 
-        const dx = x * cellPx
-        const dy = y * cellPx
+        const dx = x * cellPx + gap
+        const dy = y * cellPx + gap
+        const dw = cellPx - gap * 2
+        const dh = cellPx - gap * 2
+        map[y * gridCols + x] = best
         if (best) {
-          ctx.drawImage(best.img, dx, dy, cellPx, cellPx)
+          ctx.drawImage(best.img, dx, dy, dw, dh)
           recent.set(best, step)
         } else {
           ctx.fillStyle = `rgb(${r},${g},${b})`
-          ctx.fillRect(dx, dy, cellPx, cellPx)
+          ctx.fillRect(dx, dy, dw, dh)
         }
         // 색 보정: 대상 칸 색을 반투명으로 덮어 닮음새를 강화
         if (blend > 0) {
           ctx.globalAlpha = blend
           ctx.fillStyle = `rgb(${r},${g},${b})`
-          ctx.fillRect(dx, dy, cellPx, cellPx)
+          ctx.fillRect(dx, dy, dw, dh)
           ctx.globalAlpha = 1
         }
       }
     }
-  }, [cols, blend, unique])
+    gridRef.current = { cols: gridCols, rows: gridRows, cellPx, map }
+  }, [cols, blend, unique, grid])
 
   // 준비 완료/설정 변경 시 재생성
   useEffect(() => {
     if (ready) generate()
   }, [ready, generate])
 
+  // 캔버스 클릭 → 해당 타일의 원본 사진 표시
+  const onCanvasClick = (e: React.MouseEvent<HTMLCanvasElement>) => {
+    e.stopPropagation()
+    const canvas = canvasRef.current
+    const g = gridRef.current
+    if (!canvas || g.cellPx === 0) return
+    const rect = canvas.getBoundingClientRect()
+    const cx = (e.clientX - rect.left) * (canvas.width / rect.width)
+    const cy = (e.clientY - rect.top) * (canvas.height / rect.height)
+    const col = Math.floor(cx / g.cellPx)
+    const row = Math.floor(cy / g.cellPx)
+    if (col < 0 || row < 0 || col >= g.cols || row >= g.rows) return
+    const tile = g.map[row * g.cols + col]
+    if (tile) setPicked(tile.asset)
+  }
+
   const save = () => {
     const canvas = canvasRef.current
     if (!canvas) return
@@ -207,6 +240,10 @@ export function MosaicView(props: {
           />
           <span className="w-9 tabular-nums text-slate-400">{Math.round(blend * 100)}%</span>
         </label>
+        <label className="flex items-center gap-1.5 cursor-pointer">
+          <input type="checkbox" checked={grid} onChange={(e) => setGrid(e.target.checked)} />
+          <span>{t('mosaic.grid')}</span>
+        </label>
         <label className="flex items-center gap-1.5 cursor-pointer">
           <input type="checkbox" checked={unique} onChange={(e) => setUnique(e.target.checked)} />
           <span>{t('mosaic.unique')}</span>
@@ -221,19 +258,57 @@ export function MosaicView(props: {
       </div>
 
       {/* 캔버스 */}
-      <div className="flex-1 min-h-0 overflow-auto flex items-center justify-center p-4" onClick={props.onClose}>
+      <div className="flex-1 min-h-0 overflow-auto flex flex-col items-center justify-center p-4 gap-2" onClick={props.onClose}>
         {!ready ? (
           <p className="text-slate-400 text-sm">{t('mosaic.building')}</p>
         ) : tileCount < 4 ? (
           <p className="text-slate-400 text-sm max-w-md text-center">{t('mosaic.tooFew')}</p>
         ) : (
-          <canvas
-            ref={canvasRef}
-            onClick={(e) => e.stopPropagation()}
-            className="max-w-full max-h-full object-contain shadow-2xl"
-          />
+          <>
+            <canvas
+              ref={canvasRef}
+              onClick={onCanvasClick}
+              className="max-w-full max-h-full object-contain shadow-2xl cursor-pointer"
+            />
+            <p className="text-[11px] text-slate-500 shrink-0" onClick={(e) => e.stopPropagation()}>
+              {t('mosaic.clickHint')}
+            </p>
+          </>
         )}
       </div>
+
+      {/* 타일 클릭 → 원본 사진 */}
+      {picked && <PickedPhoto asset={picked} onClose={() => setPicked(null)} />}
+    </div>
+  )
+}
+
+/** 모자이크 타일을 클릭했을 때 뜨는 원본 사진 오버레이 */
+function PickedPhoto(props: { asset: IndexedAsset; onClose: () => void }): JSX.Element {
+  const { asset } = props
+  const [failed, setFailed] = useState(false)
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') props.onClose()
+    }
+    window.addEventListener('keydown', onKey)
+    return () => window.removeEventListener('keydown', onKey)
+  }, [props])
+  return (
+    <div
+      className="fixed inset-0 z-[60] bg-black/92 flex flex-col items-center justify-center gap-3 p-6"
+      onClick={props.onClose}
+    >
+      <img
+        src={failed ? thumbUrl(asset.contentHash) : mediaUrl(asset.path)}
+        alt={baseName(asset.path)}
+        className="max-w-full max-h-[82vh] object-contain shadow-2xl"
+        onClick={(e) => e.stopPropagation()}
+        onError={() => setFailed(true)}
+      />
+      <div className="mono text-xs text-slate-300 text-center" onClick={(e) => e.stopPropagation()}>
+        {baseName(asset.path)}
+      </div>
     </div>
   )
 }
diff --git a/src/shared/i18n.ts b/src/shared/i18n.ts
index 4a37fe8..1ac6f74 100644
--- a/src/shared/i18n.ts
+++ b/src/shared/i18n.ts
@@ -299,6 +299,11 @@ export const MESSAGES: Table = {
   'mosaic.resolution': { ko: '해상도', en: 'Resolution' },
   'mosaic.blend': { ko: '색 보정', en: 'Color blend' },
   'mosaic.unique': { ko: '중복 줄이기', en: 'Reduce repeats' },
+  'mosaic.grid': { ko: '격자선', en: 'Grid lines' },
+  'mosaic.clickHint': {
+    ko: '타일을 클릭하면 그 자리에 쓰인 원본 사진을 봅니다.',
+    en: 'Click a tile to see the source photo placed there.'
+  },
   'mosaic.save': { ko: 'PNG 저장', en: 'Save PNG' },
   'mosaic.building': { ko: '타일 색상 분석 중…', en: 'Analyzing tile colors…' },
   'mosaic.tooFew': {