diff --git a/backend/app/routers/ai_tools.py b/backend/app/routers/ai_tools.py
index 7bf0cc1..bec517c 100644
--- a/backend/app/routers/ai_tools.py
+++ b/backend/app/routers/ai_tools.py
@@ -745,6 +745,179 @@ async def enhance(req: EnhanceRequest):
         raise HTTPException(status_code=500, detail=str(e))
 
 
+# ─── Subject replace ─────────────────────────────────────────────────────────
+
+class ExtractSubjectRequest(BaseModel):
+    image: str  # base64
+
+
+class ReplaceSubjectRequest(BaseModel):
+    background_image: str         # base64 — image whose background we keep
+    subject_image: str            # base64 — image whose subject we extract
+    mask: Optional[str] = None    # base64 — white = where the subject should land
+    match_colors: bool = True     # blend subject color stats toward background
+
+
+def _extract_subject_bytes(image_bytes: bytes) -> bytes:
+    """Remove background from image using rembg; return RGBA PNG bytes."""
+    if rembg_available():
+        return remove_background_rembg(image_bytes)
+    raise RuntimeError(
+        "rembg is not installed. Run: pip install rembg  (or add it to requirements.txt)"
+    )
+
+
+def _color_transfer_lab(subj_rgba: "Image", bg_rgb: "Image", blend: float = 0.45) -> "Image":
+    """
+    Partial LAB color transfer: nudge subject color statistics 'blend' fraction
+    toward the background's statistics so it looks like it belongs in the scene.
+    """
+    import cv2
+    import numpy as np
+    from PIL import Image
+
+    src_arr = np.array(subj_rgba.convert("RGB"), dtype=np.float32)
+    tgt_arr = np.array(bg_rgb.convert("RGB"), dtype=np.float32)
+
+    alpha = np.array(subj_rgba.split()[3])
+    subject_mask = alpha > 10
+
+    if not subject_mask.any():
+        return subj_rgba
+
+    src_lab = cv2.cvtColor(src_arr.astype(np.uint8), cv2.COLOR_RGB2LAB).astype(np.float32)
+    tgt_lab = cv2.cvtColor(tgt_arr.astype(np.uint8), cv2.COLOR_RGB2LAB).astype(np.float32)
+
+    for ch in range(3):
+        src_ch = src_lab[:, :, ch]
+        src_pixels = src_ch[subject_mask]
+        tgt_pixels = tgt_lab[:, :, ch].flatten()
+
+        src_mean, src_std = float(src_pixels.mean()), float(src_pixels.std()) + 1e-6
+        tgt_mean, tgt_std = float(tgt_pixels.mean()), float(tgt_pixels.std()) + 1e-6
+
+        adjusted_std = src_std + blend * (tgt_std - src_std)
+        adjusted = (src_ch - src_mean) * (adjusted_std / src_std) + src_mean + blend * (tgt_mean - src_mean)
+        src_lab[:, :, ch] = np.clip(adjusted, 0, 255)
+
+    result_rgb = cv2.cvtColor(src_lab.astype(np.uint8), cv2.COLOR_LAB2RGB)
+    r, g, b = result_rgb[:, :, 0], result_rgb[:, :, 1], result_rgb[:, :, 2]
+    return Image.merge("RGBA", [
+        Image.fromarray(r), Image.fromarray(g),
+        Image.fromarray(b), Image.fromarray(alpha),
+    ])
+
+
+def _do_replace_subject(
+    bg_bytes: bytes,
+    subj_bytes: bytes,
+    mask_bytes: Optional[bytes],
+    match_colors: bool,
+) -> bytes:
+    """Core compositing: extract subject → scale → color-match → paste onto background."""
+    import numpy as np
+    from PIL import Image
+
+    bg_img = Image.open(BytesIO(bg_bytes)).convert("RGBA")
+
+    subj_rgba = Image.open(BytesIO(_extract_subject_bytes(subj_bytes))).convert("RGBA")
+
+    # Determine target placement bounding box from mask or full canvas
+    if mask_bytes:
+        mask_img = Image.open(BytesIO(mask_bytes)).convert("L")
+        if mask_img.size != bg_img.size:
+            mask_img = mask_img.resize(bg_img.size, Image.LANCZOS)
+        mask_arr = np.array(mask_img)
+        ys, xs = np.where(mask_arr > 128)
+    else:
+        mask_img = None
+        mask_arr = None
+        ys, xs = np.array([]), np.array([])
+
+    if len(xs) > 0:
+        minx, maxx = int(xs.min()), int(xs.max())
+        miny, maxy = int(ys.min()), int(ys.max())
+    else:
+        minx, miny = 0, 0
+        maxx, maxy = bg_img.width - 1, bg_img.height - 1
+
+    target_w = maxx - minx + 1
+    target_h = maxy - miny + 1
+
+    # Scale subject to fit target area, preserving aspect ratio
+    sw, sh = subj_rgba.size
+    scale = min(target_w / sw, target_h / sh)
+    new_w = max(1, round(sw * scale))
+    new_h = max(1, round(sh * scale))
+    subj_scaled = subj_rgba.resize((new_w, new_h), Image.LANCZOS)
+
+    # Optional color transfer to blend lighting/tone
+    if match_colors:
+        subj_scaled = _color_transfer_lab(subj_scaled, bg_img.convert("RGB"))
+
+    # Center in target area
+    px = minx + (target_w - new_w) // 2
+    py = miny + (target_h - new_h) // 2
+
+    result = bg_img.copy()
+
+    if mask_img is not None and len(xs) > 0:
+        # Build a full-canvas RGBA layer for the subject
+        subj_canvas = Image.new("RGBA", bg_img.size, (0, 0, 0, 0))
+        subj_canvas.paste(subj_scaled, (px, py), subj_scaled.split()[3])
+        # Clip subject's alpha to the selection mask
+        sc_arr = np.array(subj_canvas)
+        sc_arr[:, :, 3] = np.minimum(sc_arr[:, :, 3], mask_arr).astype(np.uint8)
+        subj_canvas = Image.fromarray(sc_arr)
+        result.paste(subj_canvas, (0, 0), subj_canvas.split()[3])
+    else:
+        result.paste(subj_scaled, (px, py), subj_scaled.split()[3])
+
+    out = BytesIO()
+    result.convert("RGB").save(out, format="PNG")
+    return out.getvalue()
+
+
+@router.post("/image/extract-subject")
+async def extract_subject(req: ExtractSubjectRequest):
+    """
+    Remove background from an image and return the subject with transparency (RGBA PNG).
+    Uses rembg (AI-powered) when available.
+    """
+    try:
+        result = await asyncio.get_event_loop().run_in_executor(
+            None, _extract_subject_bytes, _decode(req.image)
+        )
+        return {"result": _encode(result)}
+    except Exception as e:
+        import traceback; traceback.print_exc()
+        raise HTTPException(status_code=500, detail=str(e))
+
+
+@router.post("/image/replace-subject")
+async def replace_subject(req: ReplaceSubjectRequest):
+    """
+    Extract the primary subject from `subject_image` (via rembg background removal),
+    scale it to fit the `mask` selection on `background_image`, apply optional LAB
+    color transfer for lighting consistency, and composite the result.
+
+    Returns the composited image as base64 PNG.
+    """
+    try:
+        result = await asyncio.get_event_loop().run_in_executor(
+            None,
+            _do_replace_subject,
+            _decode(req.background_image),
+            _decode(req.subject_image),
+            _decode(req.mask) if req.mask else None,
+            req.match_colors,
+        )
+        return {"result": _encode(result)}
+    except Exception as e:
+        import traceback; traceback.print_exc()
+        raise HTTPException(status_code=500, detail=str(e))
+
+
 # ─── Extract colors ───────────────────────────────────────────────────────────
 
 class ExtractColorsRequest(BaseModel):
diff --git a/frontend/src/js/config-menu.js b/frontend/src/js/config-menu.js
index 3efb940..48e42dd 100644
--- a/frontend/src/js/config-menu.js
+++ b/frontend/src/js/config-menu.js
@@ -344,6 +344,11 @@ const menuDefinition = [
 				ellipsis: true,
 				target: 'image/remove_background.remove_background'
 			},
+			{
+				name: 'Replace Subject (AI)...',
+				ellipsis: true,
+				target: 'image/replace_subject.replace_subject'
+			},
 			{
 				name: 'Prepare for Print...',
 				ellipsis: true,
diff --git a/frontend/src/js/modules/image/replace_subject.js b/frontend/src/js/modules/image/replace_subject.js
new file mode 100644
index 0000000..796aadd
--- /dev/null
+++ b/frontend/src/js/modules/image/replace_subject.js
@@ -0,0 +1,252 @@
+/**
+ * Replace Subject — extract the primary subject from a source photo and
+ * composite it onto the current layer's background.
+ *
+ * Workflow:
+ *   1. User selects the subject area via Smart Select (optional but recommended).
+ *   2. Opens this module → picks a source photo.
+ *   3. Backend removes the background from the source photo (rembg / AI),
+ *      scales the extracted subject to fit the selection (or the canvas center),
+ *      applies LAB color transfer so the lighting matches the background, and
+ *      returns the composited image.
+ */
+
+import app from './../../app.js';
+import config from './../../config.js';
+import Base_layers_class from './../../core/base-layers.js';
+import alertify from './../../../../node_modules/alertifyjs/build/alertify.min.js';
+import { showProgress, hideProgress } from './../../libs/progress_overlay.js';
+
+const BASE = window.API_BASE_URL || '';
+
+var instance = null;
+
+class Image_replace_subject_class {
+
+    constructor() {
+        if (instance) return instance;
+        instance = this;
+        this.Base_layers = new Base_layers_class();
+        this.isProcessing = false;
+    }
+
+    replace_subject() {
+        if (this.isProcessing) {
+            alertify.warning('Already processing… please wait');
+            return;
+        }
+        if (config.layer.type !== 'image') {
+            alertify.error('Current layer must be an image.');
+            return;
+        }
+        this._showDialog();
+    }
+
+    // ── Private ───────────────────────────────────────────────────────────────
+
+    _showDialog() {
+        var hasSel = !!(window.smartSelectMask && window.smartSelectMask.canvas);
+
+        // Build a dialog manually so we can embed a file input
+        var overlay = document.createElement('div');
+        overlay.style.cssText = [
+            'position:fixed', 'inset:0', 'background:rgba(0,0,0,0.6)',
+            'z-index:20000', 'display:flex', 'align-items:center', 'justify-content:center',
+        ].join(';');
+
+        var box = document.createElement('div');
+        box.style.cssText = [
+            'background:#1a1a2e', 'border:1px solid #3a3a6a', 'border-radius:12px',
+            'padding:24px', 'min-width:380px', 'max-width:460px',
+            'font-family:sans-serif', 'color:#d0d0e0', 'font-size:13px',
+        ].join(';');
+
+        // Title
+        var title = document.createElement('div');
+        title.textContent = 'Replace Subject';
+        title.style.cssText = 'font-size:16px;font-weight:bold;color:#aaaaff;margin-bottom:6px';
+        box.appendChild(title);
+
+        var sub = document.createElement('div');
+        sub.textContent = hasSel
+            ? 'Subject will be placed inside your current selection.'
+            : 'No selection active — subject will be centred on the canvas.  Use Smart Select first for precise placement.';
+        sub.style.cssText = 'font-size:11px;color:#7777aa;margin-bottom:16px;line-height:1.4';
+        box.appendChild(sub);
+
+        // File picker label + preview row
+        var fileRow = document.createElement('div');
+        fileRow.style.cssText = 'display:flex;align-items:center;gap:10px;margin-bottom:12px';
+        var fileLabel = document.createElement('label');
+        fileLabel.textContent = 'Source photo:';
+        fileLabel.style.cssText = 'color:#aaa;width:100px;flex-shrink:0';
+        var fileInput = document.createElement('input');
+        fileInput.type = 'file';
+        fileInput.accept = 'image/*';
+        fileInput.style.cssText = 'flex:1;background:#0f0f1a;color:#ccc;border:1px solid #4a4a8a;border-radius:5px;padding:4px 8px;font-size:12px;cursor:pointer';
+        fileRow.appendChild(fileLabel);
+        fileRow.appendChild(fileInput);
+        box.appendChild(fileRow);
+
+        // Thumbnail preview
+        var preview = document.createElement('img');
+        preview.style.cssText = 'display:none;max-width:100%;max-height:160px;border-radius:6px;margin-bottom:12px;border:1px solid #3a3a6a';
+        box.appendChild(preview);
+        fileInput.addEventListener('change', () => {
+            var f = fileInput.files[0];
+            if (!f) return;
+            var url = URL.createObjectURL(f);
+            preview.src = url;
+            preview.style.display = 'block';
+            preview.onload = () => URL.revokeObjectURL(url);
+        });
+
+        // Match colors checkbox
+        var colorRow = document.createElement('div');
+        colorRow.style.cssText = 'display:flex;align-items:center;gap:8px;margin-bottom:16px';
+        var colorCheck = document.createElement('input');
+        colorCheck.type = 'checkbox';
+        colorCheck.checked = true;
+        colorCheck.id = 'rs-match-colors';
+        var colorLabel = document.createElement('label');
+        colorLabel.htmlFor = 'rs-match-colors';
+        colorLabel.textContent = 'Match background lighting & color tone';
+        colorLabel.style.cssText = 'color:#bbb;cursor:pointer';
+        colorRow.appendChild(colorCheck);
+        colorRow.appendChild(colorLabel);
+        box.appendChild(colorRow);
+
+        // Buttons
+        var btnRow = document.createElement('div');
+        btnRow.style.cssText = 'display:flex;gap:8px;justify-content:flex-end';
+
+        var cancelBtn = _btn('Cancel', '#2a2a4a', '#8888aa');
+        cancelBtn.onclick = () => { document.body.removeChild(overlay); };
+
+        var goBtn = _btn('Replace Subject', '#1a3a5a', '#88ccff');
+        goBtn.style.fontWeight = 'bold';
+        goBtn.onclick = async () => {
+            var file = fileInput.files[0];
+            if (!file) {
+                alertify.warning('Please pick a source photo first.');
+                return;
+            }
+            document.body.removeChild(overlay);
+            await this._run(file, colorCheck.checked);
+        };
+
+        btnRow.appendChild(cancelBtn);
+        btnRow.appendChild(goBtn);
+        box.appendChild(btnRow);
+
+        overlay.appendChild(box);
+        overlay.addEventListener('click', (e) => { if (e.target === overlay) document.body.removeChild(overlay); });
+        document.body.appendChild(overlay);
+    }
+
+    async _run(file, matchColors) {
+        this.isProcessing = true;
+        showProgress('Extracting subject and compositing…', 20);
+
+        try {
+            var subjectBase64 = await _fileToBase64(file);
+            var bgBase64      = _getLayerBase64();
+            var maskBase64    = _getMaskBase64();
+
+            var res = await _post('/api/image/replace-subject', {
+                background_image: bgBase64,
+                subject_image:    subjectBase64,
+                mask:             maskBase64 || undefined,
+                match_colors:     matchColors,
+            });
+
+            var img = new Image();
+            img.onload = () => {
+                var canvas = document.createElement('canvas');
+                canvas.width  = img.width;
+                canvas.height = img.height;
+                canvas.getContext('2d').drawImage(img, 0, 0);
+
+                app.State.do_action(
+                    new app.Actions.Bundle_action('replace_subject', 'Replace Subject', [
+                        new app.Actions.Update_layer_image_action(canvas, config.layer.id)
+                    ])
+                );
+
+                // Clear selection if one was used
+                if (window.smartSelectMask) {
+                    window.smartSelectMask = null;
+                    config.need_render = true;
+                }
+
+                hideProgress();
+                alertify.success('Subject replaced!');
+                this.isProcessing = false;
+            };
+            img.onerror = () => {
+                hideProgress();
+                alertify.error('Failed to load result image.');
+                this.isProcessing = false;
+            };
+            img.src = 'data:image/png;base64,' + res.result;
+
+        } catch (e) {
+            hideProgress();
+            alertify.error('Replace subject failed: ' + (e.message || e));
+            this.isProcessing = false;
+        }
+    }
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+function _getLayerBase64() {
+    var canvas = document.createElement('canvas');
+    canvas.width  = config.layer.width_original;
+    canvas.height = config.layer.height_original;
+    canvas.getContext('2d').drawImage(config.layer.link, 0, 0);
+    return canvas.toDataURL('image/png').split(',')[1];
+}
+
+function _getMaskBase64() {
+    var m = window.smartSelectMask;
+    if (!m || !m.canvas) return null;
+    var w = config.layer.width_original;
+    var h = config.layer.height_original;
+    var canvas = document.createElement('canvas');
+    canvas.width  = w;
+    canvas.height = h;
+    canvas.getContext('2d').drawImage(m.canvas, 0, 0, w, h);
+    return canvas.toDataURL('image/png').split(',')[1];
+}
+
+function _fileToBase64(file) {
+    return new Promise((resolve, reject) => {
+        var reader = new FileReader();
+        reader.onload  = (e) => resolve(e.target.result.split(',')[1]);
+        reader.onerror = reject;
+        reader.readAsDataURL(file);
+    });
+}
+
+function _btn(text, bg, color) {
+    var b = document.createElement('button');
+    b.textContent = text;
+    b.style.cssText = 'background:' + bg + ';color:' + color + ';border:1px solid #3a3a6a;padding:6px 14px;border-radius:6px;cursor:pointer;font-size:12px';
+    return b;
+}
+
+async function _post(path, body) {
+    var r = await fetch(BASE + path, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(body),
+    });
+    if (!r.ok) {
+        var err = await r.json().catch(() => ({ detail: r.statusText }));
+        throw new Error(err.detail || 'Request failed');
+    }
+    return r.json();
+}
+
+export default Image_replace_subject_class;
diff --git a/frontend/src/js/tools/selection_actions.js b/frontend/src/js/tools/selection_actions.js
index b7ec705..104cc8c 100644
--- a/frontend/src/js/tools/selection_actions.js
+++ b/frontend/src/js/tools/selection_actions.js
@@ -144,6 +144,14 @@ export class SelectionActions {
             () => this._pasteFromClipboard()
         ));
 
+        // Replace subject from file
+        panel.appendChild(_actionCard(
+            'Replace subject from file',
+            '#1a2a2a', '#66ddcc',
+            'Pick any photo — AI extracts its subject and places it here, matching background lighting',
+            () => this._replaceSubjectFromFile()
+        ));
+
         // Custom AI edit prompt
         var aiWrap = document.createElement('div');
         aiWrap.style.cssText = 'background:#16213e;border-radius:7px;padding:7px 10px';
@@ -323,6 +331,42 @@ export class SelectionActions {
         }
     }
 
+    async _replaceSubjectFromFile() {
+        if (!this._check()) return;
+
+        // Open a file picker — no clipboard API required
+        var fileInput = document.createElement('input');
+        fileInput.type = 'file';
+        fileInput.accept = 'image/*';
+
+        fileInput.onchange = async () => {
+            var file = fileInput.files[0];
+            if (!file) return;
+
+            var subjectBase64 = await _fileToBase64(file);
+            this.hide();
+            showProgress('Extracting subject and compositing…', 15);
+
+            try {
+                var res = await _post('/api/image/replace-subject', {
+                    background_image: this._imageData,
+                    subject_image:    subjectBase64,
+                    mask:             this._maskData,
+                    match_colors:     true,
+                });
+                this.tool.updateLayerWithResult(res.result);
+                this.tool.clearSelection();
+                hideProgress();
+                alertify.success('Subject replaced with background color matching!');
+            } catch (e) {
+                hideProgress();
+                alertify.error('Replace subject failed: ' + e.message);
+            }
+        };
+
+        fileInput.click();
+    }
+
     _check() {
         if (!this._imageData || !this._maskData) {
             alertify.error('No selection data. Make a new selection first.');
@@ -411,3 +455,12 @@ function _blobToBase64(blob) {
         reader.readAsDataURL(blob);
     });
 }
+
+function _fileToBase64(file) {
+    return new Promise((resolve, reject) => {
+        var reader = new FileReader();
+        reader.onload  = (e) => resolve(e.target.result.split(',')[1]);
+        reader.onerror = reject;
+        reader.readAsDataURL(file);
+    });
+}