NABA Image (Gemini REST) Node

NABA Image (Gemini REST) Node

Version: v1.2.0 (REST-only minimal)

Simplified Gemini 2.5 Flash Image Preview node for ComfyUI. REST-only for stability, two optional reference images, padded aspect ratio resizing (no stretching), and basic sampling controls. All extra debug layers, SDK path, multi-seed, and legacy compatibility code removed to avoid crashes.

Differences vs Earlier Advanced Version

| Aspect | v1.2.0 REST | v1.1.x Hybrid | |--------|-------------|---------------| | Transport | REST only | SDK + REST fallback | | Reference Images | Up to 2 | Up to 2 (previously 5 in older drafts) | | Aspect Handling | Padded (preserve composition) | Resize + stretch fallback | | Seeds | Single seed (pass-through) | Multi-seed list + retries | | Safety Toggles | None (model defaults) | block_none flag | | Fallback | Gray padded image | Black or blank tensor | | Debug Flags | None special | Many env toggles | | Code Footprint | ~150 lines | 400+ lines |

Features

• Text → Image via Gemini REST endpoint
• Two optional reference images with individual strength sliders (0.0–2.0)
• Aspect ratio dropdown (1:1 .. 21:9) with padding (no stretching)
• Sampling controls: temperature, top_p, top_k (string dropdowns)
• Single seed pass-through (future: deterministic strategies)
• Graceful fallback → neutral gray padded image if no candidate returned
• Minimal dependencies: requests, Pillow, torch, numpy

Inputs (v1.2.0)

| Name | Type | Notes | |------|------|-------| | prompt | STRING | Default: refined descriptive prompt | | aspect_ratio | DROPDOWN | Long side ~1024, padded to exact ratio | | seed | INT | Currently pass-through only | | image_1 | IMAGE | Optional reference image | | image_1_strength | FLOAT | Influence 0.0–2.0 (currently passed as metadata placeholder) | | image_2 | IMAGE | Optional second reference | | image_2_strength | FLOAT | Influence 0.0–2.0 | | temperature | DROPDOWN | Creative randomness | | top_p | DROPDOWN | Nucleus sampling | | top_k | DROPDOWN | Token cap | | (output) | IMAGE | Tensor 1xHxWx3 float32 0..1 |

API Key Setup

export GEMINI_API_KEY=YOUR_KEY
# or create api_key.txt beside this file
echo YOUR_KEY > custom_nodes/gemini_image_gen/api_key.txt

Usage

Search for: NABA Image (Gemini API) under category image/NABA. Provide a prompt and pick an aspect ratio. (Legacy graphs supplying size_preset continue to function.) Attach up to 5 reference images for guidance.

Environment Variables

| Var | Purpose | Default | |-----|---------|---------| | GEMINI_API_KEY | Auth key (required) | - | | GEMINI_URL | Override REST endpoint | preview URL |

Design Notes (Learned from Nano Banana Repo)

1. Category clarity: use a vendor/feature prefix to avoid collisions (image/NABA vs nested reused Gemini categories).
2. Consistent naming: single exported class; avoid legacy alias to prevent duplicate UI entries.
3. Explicit model constraints: Upstream project documents fixed 1024x1024. Add TODO to interrogate SDK for actual size limits.
4. Structured error handling: Instead of raising mid-graph, returning a blank tensor preserves graph continuity.
5. Multi-ref implemented: builds parts list for SDK, mirrors Nano Banana style for REST.
6. Configuration hygiene: Prefer one key variable name (GEMINI_API_KEY) but accept legacy REPLICATE_API_KEY for transition in REST path.
7. Resilience: Automatic REST fallback provides alternate path when SDK returns no inline image.
8. Simplicity bias: Core kept in single file for easier auditing.
9. Exposed common text generation controls (temperature/top_p/top_k) so workflows can experiment with stylistic variance.

Roadmap

• True influence weighting (currently metadata only)
• Deterministic seed perturbation method
• Optional retry toggle
• Safety tuning inputs

Troubleshooting

| Symptom | Cause | Action | |---------|-------|--------| | Node missing | Import error | Check terminal logs for stacktrace | | Always black image | API key missing OR both SDK+REST failed | Ensure key, force REST to isolate, enable debug | | Duplicate nodes | Old alias or other Gemini plugins | Remove aliases / rename categories | | Blank but no error with refs | No inline image part returned | Set GEMINI_VERBOSE_PARTS=1 to inspect parts | | Want exception instead of blank | Silent fallback masking error | Set GEMINI_RAISE=1 |

Debug

Minimal by design. If issues arise print output appears in terminal. Add print()s locally if deeper tracing is needed.

Minimal Test Snippet

from custom_nodes.gemini_image_gen.gemini_image import NABAImageNodeREST
n = NABAImageNodeREST()
tensor, = n.generate(prompt="a tiny chrome banana on a desk", aspect_ratio="1:1")
print(tensor.shape)

License / Disclaimer

Follows ComfyUI usage context. Not affiliated with Google. API usage may incur cost.

Versioning (Recent)

• 1.2.0 – REST-only minimal rewrite (this document)
• 1.1.x – Hybrid SDK/REST advanced (retired)
• 0.x – Experimental iterations (see older logs)