From 1b760f3b413d28652965a51f629d3c2b8d33ce22 Mon Sep 17 00:00:00 2001
From: skal <pascal.massimino@gmail.com>
Date: Sat, 14 Feb 2026 01:01:52 +0100
Subject: Fix --mix option: blend prev layer with static p4-p7, not p0-p3

Updated gen_identity_weights.py --mix mode to use static features
p4-p7 (uv_x, uv_y, sin20_y, bias) at channels 8-11 instead of
p0-p3 (RGB+D) at channels 4-7.

Before: 0.5*prev[i] + 0.5*static_p{i} (channels 4-7)
After:  0.5*prev[i] + 0.5*static_p{4+i} (channels 8-11)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 training/diagnose_255_to_253.md | 69 -----------------------------------------
 1 file changed, 69 deletions(-)
 delete mode 100644 training/diagnose_255_to_253.md

(limited to 'training/diagnose_255_to_253.md')

diff --git a/training/diagnose_255_to_253.md b/training/diagnose_255_to_253.md
deleted file mode 100644
index 764d328..0000000
--- a/training/diagnose_255_to_253.md
+++ /dev/null
@@ -1,69 +0,0 @@
-# Diagnosis: 255 → 253 Loss (-2 LSBs)
-
-## Findings
-
-### F16 Precision
-✅ **No loss:** 1.0 → f16(0x3c00) → 1.0 (exact round-trip)
-
-### Visualization Scale
-⚠️ **Inconsistent:**
-- Layer 1 uses `vizScale = 0.5` (line 1530)
-- Should render as 128, not 253
-- **User seeing 253 suggests viewing Static Features (scale=1.0), not CNN output**
-
-### Suspected Issue: Input Alpha Channel
-
-**Code:** `tools/cnn_v2_test/index.html` line 1233
-```javascript
-depthData[i] = pixels[i * 4 + 3] / 255.0;  // Alpha from canvas
-```
-
-**Hypothesis:** Input PNG alpha channel = 253 (not 255)
-- Browsers may set alpha < 255 for certain images
-- Pre-multiplied alpha corrections
-- PNG encoder compression artifacts
-
-### Test
-
-**Check input alpha:**
-```javascript
-// In HTML tool console:
-const canvas = document.createElement('canvas');
-canvas.width = tester.image.width;
-canvas.height = tester.image.height;
-const ctx = canvas.getContext('2d');
-ctx.drawImage(tester.image, 0, 0);
-const imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
-const alpha = imgData.data[3];  // First pixel alpha
-console.log('First pixel alpha:', alpha);
-```
-
-### Alternative: C++ Reference
-
-Check if `cnn_test` tool produces same -2 loss:
-```bash
-# Generate solid white 8×8 test image with alpha=255
-python3 -c "
-from PIL import Image
-import numpy as np
-img = np.ones((8, 8, 4), dtype=np.uint8) * 255
-Image.fromarray(img, 'RGBA').save('test_white_255.png')
-print('Created test_white_255.png: all pixels RGBA=(255,255,255,255)')
-"
-
-# Test with HTML tool → check if p3 = 1.0 or 0.9921875
-# Test with cnn_test → compare output
-./build/cnn_test test_white_255.png output.png --cnn-version 2 --debug-hex
-```
-
-### Next Steps
-
-1. **Verify input:** Check alpha channel of user's input image
-2. **Add debug:** Log first pixel RGBA values in HTML tool
-3. **Compare:** Run same image through C++ cnn_test
-4. **Isolate:** Test with synthetic 255 alpha image
-
-## Conclusion
-
-**Most likely:** Input image alpha ≠ 255, already 253 before CNN processing.
-**Verify:** User should check input PNG metadata and alpha channel values.
-- 
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