ComfyUI Extension: NABA Image (Gemini REST) Node

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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.

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    README

    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)