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Version 2.6

Compact multimodal model for CPU-friendly image + text generation.

Nthuku-Fast 2.6

Version 2.6 is a full fine-tune from 2.5 trained on a vision-only filtered manifest. This release improves stored training loss/perplexity and slightly improves the current weakness benchmark score versus 2.3/2.4/2.5.

What Changed In 2.6

• Training source: nthuku-fast-2.5
• Mode: full fine-tune
• Epochs: 10
• Max samples: 23,086
• Data file: nthuku_dataset/manifest_train_vision_only.parquet
• Objective of this pass: reduce text-only contamination that previously triggered code-like outputs during image prompts

Key Metrics

Training Metrics (from config)

Interpretation:

• 2.6 has the best stored training objective in this 2.3 to 2.6 range.
• Lower training loss did not fully translate into robust instruction-following behavior yet, so this should be treated as a necessary but not sufficient improvement.

Weakness Benchmark (21 auto probes) — With Real Image-Backed Probes

Evaluation re-run with 15,000 real images from vision_text sources in probes/ directory:

• eval_results_23_with_images/weakness_report.json
• eval_results_24_with_images/weakness_report.json
• eval_results_25_with_images/weakness_report.json
• eval_results_26_with_images/weakness_report.json

Key Findings:

• 2.6 achieves best overall score (0.6483) with real images
• 2.6 vision/counting improved to 0.6348 (from 0.6000 in 2.4/2.5)
• Language/instruction remains stable bottleneck at 0.5333 across all versions
• Most other vision dimensions (spatial, attribute, ocr, scene) plateau at 0.6 baseline with all models

Delta vs prior:

• 2.6 - 2.5: +0.0032 overall
• 2.6 - 2.4: +0.0032 overall
• 2.6 - 2.3: +0.0016 overall

Speed (from probe_results elapsed_s)

Interpretation:

• 2.6 is materially faster than 2.4 and 2.5 on this harness.
• 2.6 is close to 2.3 latency while scoring slightly higher overall.

Evaluation Status: Image-Backed Probes Active

As of the latest evaluation run, the probe suite now contains 15,000 real images sourced from:

• sources/vision_text/caption/images/
• sources/vision_text/vqa/images/
• sources/vision_text/conversation/images/

Current state:

• ✅ probes/ populated with real images
• ✅ Vision probe scores now grounded in actual image inference
• ⚠️ Most vision dimensions still plateau at 0.6 baseline, indicating fundamental capability gaps

Interpretation:

• Vision scores are now valid multi-modal evaluations
• 0.6 baseline on most vision dimensions suggests that instruction-constrained visual reasoning is weak across the current architecture
• Strongest signal: v2.6 improves vision/counting to 0.6348 vs. 0.6000 in prior versions, but this is still a modest gain
• Critical bottleneck: language/instruction at 0.5333 prevents models from output compliance even when visual understanding is available

Image and Response Review

Reviewed image paths

• sources/vision_text/mcqa/images/sciqa_0000000.jpg
• sources/vision_text/caption/images/coco_0004314.jpg
• sources/vision_text/detailed_caption/images/coco_0002088.jpg

Observations

1. MCQA map prompt

• Image content is clear (US map with labeled states).
• Expected answer for farthest north among the given choices is West Virginia.
• Actual terminal response for 2.6 remained mostly off-task and verbose, mixing unrelated fragments.
• Conclusion: instruction-binding for constrained visual QA is still weak.

2. General caption behavior

• Responses often over-generate repetitive filler patterns (for example repeated short tokens/phrases).
• Even when image context exists, completion drifts instead of staying compact and grounded.
• Conclusion: decoding and instruction adherence remain the dominant bottlenecks.

3. Improvement vs 2.5

• Reduced code-like contamination is partially visible in aggregate metrics (especially counting score and overall score).
• But the model is not yet reliably production-grade for strict-format visual QA/captioning.

Weakness Ranking (2.6 with Image-Backed Probes)

From eval_results_26_with_images/weakness_report.json:

Strategic Insight:

• The single largest improvement lever for v2.7 is instruction adherence (0.5333 → target 0.75+)
• Vision dimensions will not improve significantly without addressing the output format constraint issue
• The model has strong language capability (detail and fluency) but cannot reliably follow instructions on what to output

Recommended Next Step for v2.7

Step 1 is now complete: real probe pack with 15,000 images has been built and vision metrics are valid.

Focus for v2.7: Address the instruction/output-constraint bottleneck (0.5333 → 0.75+)

Remaining priority actions:

1. ✅ DONE — Build real probe pack

• Probes/ populated with 15,000 images
• Vision metrics are grounded and valid

2. Add constrained-format visual QA curriculum

• Add many samples with strict outputs:
  • single-word answers for MCQA
  • one-line numeric answers for counting
  • exact 3-sentence captions for description
• Keep high weight on image-conditioned instruction-following data
• Target: increase language/instruction from 0.5333 to 0.70+

3. Penalize repetition during evaluation and tune decoding defaults

• Use lower max_new_tokens for constrained prompts (e.g., 5-15 tokens for MCQA)
• Apply stronger repetition penalty (increase from 1.1 to 1.3-1.5)
• Implement early stopping for short-answer tasks
• Reduce verbose filler generation (observed "so so so" and "a a a" patterns in probes)

4. Add hard pass/fail validation gate

• Create 200-500 curated high-quality items with deterministic expected outputs
• Track exact-match accuracy for MCQA and format compliance rate
• Use as release gate for v2.7
• Expected outcome: avoid production deployments where instruction binding is broken

Expected outcome of v2.7: +0.15-0.20 on language/instruction while preserving 2.6's loss/perplexity and speed gains.

Local Quick Test

Text-only:

python test_local_model.py --model_dir ./nthuku-fast-2.6 --prompt "Hello, how are you?"

Vision + text:

python test_local_model.py --model_dir ./nthuku-fast-2.6 --prompt "Describe this image in English only, in 3 short sentences." --image ./image.jpg

License

Released under the Apache 2.0 License. Free to use, modify, and distribute with attribution.