diff --git a/App.tsx b/App.tsx
index ec9780c..45ae053 100644
--- a/App.tsx
+++ b/App.tsx
@@ -402,6 +402,32 @@ export default function App() {
     // never flip the watermark on/off.
   };
 
+  // The recipe exactly as the user picked it. `selectedRecipe` is NOT a safe
+  // copy of it: every slider move rewrites its `adjustments` in place
+  // (handleUpdateAdjustments), so the canonical values only survive in the
+  // film-sim table and in the saved list.
+  const pristineRecipe = (recipe: Recipe): Recipe | null => {
+    const sim = FILM_SIMS.find((f) => f.id === recipe.id);
+    if (sim) return filmSimToRecipe(sim);
+    return recipes.find((r) => r.id === recipe.id) || null;
+  };
+
+  // Every edit belongs to the mode and the photo it was made on, so it never
+  // crosses into the next session: the sliders go back to the recipe's own
+  // values, a frame picked for that still is dropped, and the custom mark —
+  // placed against that very photo — is switched back off.
+  const resetEditsToRecipe = () => {
+    const base = selectedRecipe ? pristineRecipe(selectedRecipe) : null;
+    if (base) {
+      applyRecipe(base);
+    } else {
+      setAdjustments({ ...DEFAULT_ADJUSTMENTS });
+      setSelectedFrame('none');
+    }
+    setCustomWm({ ...DEFAULT_CUSTOM_WM });
+    setCustomWmApplied({ ...DEFAULT_CUSTOM_WM });
+  };
+
   const handleUpdateAdjustments = (updates: Partial<ColorAdjustments>) => {
     // Storm guard, generic across every param: same-value writes (slider
     // micro-jitter / repeated pointer-move events) still build a fresh
@@ -595,6 +621,10 @@ export default function App() {
       setLibraryImageUri(asset.uri);
       setPhotoRotation(0);
       setMode('library');
+      // Picking from the camera is the other half of that switch (the camera
+      // button is the way back), so the camera's edits must not land on the
+      // photo: the picked still starts at the recipe's own values too.
+      if (mode !== 'library') resetEditsToRecipe();
       // Clear old GPS — will be replaced if the photo (or device) has location data
       setGpsInfo(null);
 
@@ -854,17 +884,11 @@ export default function App() {
     // placement layer left eating the camera's tap-to-focus.
     setOpenTab(null);
     setOpenParamKey(null);
-    // A frame was picked for the still it sits on; camera mode has no FRAME
-    // picker to undo it, so it must never follow the user onto the live camera
-    // (and into the capture, which burns the frame in).
+    resetEditsToRecipe();
+    // Camera mode has no FRAME picker to undo a frame, so even a recipe that
+    // carries one must not follow the user onto the live camera (and into the
+    // capture, which burns the frame in).
     if (next === 'camera') setSelectedFrame('none');
-    // Same for the custom watermark: it was placed against THAT library photo,
-    // so it must not follow the user onto the live camera either — the mark
-    // goes back to off, and re-enabling + editing it is a deliberate choice.
-    if (next === 'camera') {
-      setCustomWm({ ...DEFAULT_CUSTOM_WM });
-      setCustomWmApplied({ ...DEFAULT_CUSTOM_WM });
-    }
     setMode(next);
   };
 
diff --git a/modules/recipescam-export/android/src/main/java/com/locphamtran/recipescamera/export/RecipescamExportModule.kt b/modules/recipescam-export/android/src/main/java/com/locphamtran/recipescamera/export/RecipescamExportModule.kt
index f6f6076..4f99332 100644
--- a/modules/recipescam-export/android/src/main/java/com/locphamtran/recipescamera/export/RecipescamExportModule.kt
+++ b/modules/recipescam-export/android/src/main/java/com/locphamtran/recipescamera/export/RecipescamExportModule.kt
@@ -485,11 +485,11 @@ private fun applyTone(bmp: Bitmap, dr: Float, hl: Float, sh: Float) {
     val g = ((c shr 8) and 0xFF) / 255f
     val b = (c and 0xFF) / 255f
     val t = (0.2126f * r + 0.7152f * g + 0.0722f * b).coerceIn(0f, 1f)
-    // Wide, soft knees (see TONE_SKSL): HL rides the upper half, SH the lower.
-    val hlMask = smoothstep(0.45f, 1.00f, t)
+    // Wide, soft knees (see TONE_SKSL): HL rides the top, SH the lower half.
+    val hlMask = smoothstep(0.65f, 1.00f, t)
     val shMask = 1f - smoothstep(0.00f, 0.55f, t)
     // Pure additive luma shifts -> monotonic curve (no reversal on a ramp).
-    var o = t + hl * 0.32f * hlMask + sh * 0.34f * shMask
+    var o = t + hl * 0.22f * hlMask + sh * 0.34f * shMask
     // Dynamic range: gentle shadow lift + highlight roll (protect brights).
     o += dr * 0.12f * shMask * (1f - t)
     o -= dr * 0.18f * hlMask * t
diff --git a/src/dev/nativeBenchProbe.ts b/src/dev/nativeBenchProbe.ts
index da080c6..570b1b5 100644
--- a/src/dev/nativeBenchProbe.ts
+++ b/src/dev/nativeBenchProbe.ts
@@ -53,7 +53,7 @@ export async function nativeBenchProbe(): Promise<void> {
     console.error('[BENCH] classic-neg-on-black matrix[0..4]=' + matrix.slice(0, 5).join(','));
 
     // P2 tone parity on solid ramps (expected values computed from TONE_SKSL):
-    //  white(255) hl=-1 -> 173; gray64 sh=+1 -> 113; white dr=1 -> 209;
+    //  white(255) hl=-1 -> 199; gray64 sh=+1 -> 113; white dr=1 -> 209;
     //  gray26 sh=+1 -> 105; gray26 hl=+1 sh=-1 -> 0.
     const toneGates: Array<{ rgb: [number, number, number]; tone: { dr: number; hl: number; sh: number }; tag: string }> = [
       { rgb: [255, 255, 255], tone: { dr: 0, hl: -1, sh: 0 }, tag: 'white-hl-1' },
diff --git a/src/utils/toneShader.ts b/src/utils/toneShader.ts
index 290d995..426ffea 100644
--- a/src/utils/toneShader.ts
+++ b/src/utils/toneShader.ts
@@ -9,14 +9,15 @@ import { ColorAdjustments } from '../types';
 // turned saturated blues black under -SH and bright colours grey under -HL.
 //
 // Wide, soft knees so the knobs reach like a tone curve instead of biting only
-// at the very ends: HL rides the upper half (0.45..1.00), SH the lower half
-// (0.00..0.55), and the 0.50 midpoint moves less than 3%. Earlier narrow
+// at the very ends: HL rides only the top (0.65..1.00) so it leaves the greys
+// and midtones alone (a 0.45 knee dragged a mid-grey down) while SH rides the
+// lower half (0.00..0.55), and the 0.50 midpoint never moves. Earlier narrow
 // knees (0.80..1.00 / 0.00..0.30) made both sliders look dead on any photo
 // without true whites or blacks.
 //
 // Both knobs are pure additive shifts of the luma. That keeps the curve
-// monotonic (steepest knee slope 2.73/unit * 0.32 = 0.87, +SH overlap still
-// positive), so a brighter input can never come out darker. The earlier
+// monotonic (steepest knee slope 4.29/unit * 0.22 = 0.94, and the two knees
+// never overlap), so a brighter input can never come out darker. The earlier
 // multiplicative form was NOT monotonic: with hl=-1 a grey 0.73 came out
 // darker than 0.80.
 //
@@ -38,10 +39,10 @@ vec4 main(vec2 xy) {
   vec4 c = src.eval(xy);
   vec3 rgb = clamp(c.rgb, 0.0, 1.0);
   float t = clamp(dot(rgb, vec3(0.2126, 0.7152, 0.0722)), 0.0, 1.0);
-  float hlMask = smoothstep(0.45, 1.00, t);
+  float hlMask = smoothstep(0.65, 1.00, t);
   float shMask = 1.0 - smoothstep(0.00, 0.55, t);
   // NOTE: never name a local 'out' — it is a reserved SkSL qualifier.
-  float o = t + hl * 0.32 * hlMask + sh * 0.34 * shMask;
+  float o = t + hl * 0.22 * hlMask + sh * 0.34 * shMask;
   // Dynamic range: gentle shadow lift + highlight roll (protect brights).
   o += dr * 0.12 * shMask * (1.0 - t);
   o -= dr * 0.18 * hlMask * t;