LTX-2.3 image-to-video in ComfyUI (official template): dev FP8 checkpoint, distilled LoRA at 0.5, Gemma 3 12B FP4 text encoder, two-stage 8+3-step sampling, prompt-enhancer switch and audio output

LTX-2.3 image-to-video in ComfyUI: what the official template loads and how it runs This is a static reading of Comfy-Org workflow_templates templates/video_ltx2_3_i2v.json at commit 0cc0fba562efe9f68e48050c2b82ed6495050bc2 (144,650 bytes, sha256 860a9cea...). Nothing was imported or run. The graph is one LoadImage node feeding a subgraph called "Image to Video (LTX-2.3)", whose video goes to SaveVideo with the prefix video/LTX_2.3_i2v. Files and folders the graph declares (sizes from the template's own note): - checkpoints/ltx-2.3-22b-dev-fp8.safetensors (27.14 GB, from Lightricks/LTX-2.3-fp8). This one checkpoint also supplies the video VAE and, through LTXVAudioVAELoader, the audio VAE. - text_encoders/gemma_3_12B_it_fp4_mixed.safetensors (from Comfy-Org/ltx-2), loaded by LTXAVTextEncoderLoader together with the checkpoint. - loras/ltx_2.3_22b_distilled_1.1_lora_dynamic_fro09_avg_rank_111_bf16.safetensors (2.55 GB, from Comfy-Org/ltx-2.3), applied to the model at strength 0.5. - latent_upscale_models/ltx-2.3-spatial-upscaler-x2-1.1.safetensors (949.6 MB, from Lightricks/LTX-2.3). - loras/gemma-3-12b-it-abliterated_lora_rank64_bf16.safetensors (599.1 MB, from Comfy-Org/ltx-2), applied only to the text encoder copy used by the prompt enhancer. The template's note lists the checkpoint, both LoRAs and the upscaler with a storage tree, but leaves out the Gemma text encoder file that the graph's text-encoder loader requires. Download it too. The model URLs point at main branches, not pinned revisions. Controls on the subgraph node. Prompt; Enable Prompt Enhance (saved false); Width 1280, Height 720, Duration 5 and Frame Rate 25; the first-stage seed (saved 60540193790228); and selectors for the checkpoint, distilled LoRA, text encoder, upscaler and enhancer LoRA. Inside, a "Switch to Text to Video?" boolean (saved false) feeds the bypass input of both image-conditioning nodes. How it runs, as wired. 1. Image: resized to the set width and height (scale dimensions, center, lanczos), then rescaled so the longer side is 1536 (area), then LTXVPreprocess (saved 18). 2. Stage 1 at half size: Width/2 and Height/2 (640x360 by default) with length = Duration x Frame Rate + 1, plus an empty audio latent of the same length. The image is injected with LTXVImgToVideoInplace (saved strength 0.7). Sampling: euler, CFG 1, the first-stage seed, and 8 manual sigmas 1.0, 0.99375, 0.9875, 0.98125, 0.975, 0.909375, 0.725, 0.421875, 0.0. 3. Latent x2 upscale with the 1.1 spatial upscaler, image injected again (saved strength 1), then stage 2: euler, CFG 1, seed 42 fixed, and 3 manual sigmas 0.85, 0.7250, 0.4219, 0.0. LTXVCropGuides prepares the stage-2 conditioning. 4. Tiled VAE decode (saved 768, 64, 4096, 4) and LTX audio VAE decode, combined by CreateVideo at the set frame rate. Both stages use the dev checkpoint with the distilled LoRA at 0.5. The negative prompt is "pc game, console game, video game, cartoon, childish, ugly". LTXVConditioning and CreateVideo show a saved 24 but take the linked Frame Rate (25 by default). Prompt enhancer. When Enable Prompt Enhance is true, TextGenerateLTX2Prompt writes a new prompt from your prompt and the resized image using Gemma with the abliterated LoRA, and the switch sends that text to the positive encoder instead of yours. It is off in the saved template. Whether ComfyUI still evaluates the unused branch was not tested. The note's prompting tips: describe actions as they occur over time, all visual details you want, and the sounds and dialogue the scene needs. Size and length arithmetic. By default the length is 5 x 25 + 1 = 126 frames, which is not of the 8k+1 form the LTX-2.3 card requires (art_01M5YB5H1BAKQCJ0GTV8SVV80R); 121 or 129 would be. Stage 1 runs at 640x360, and 360 (and the final 720) is not a multiple of 32 as that card requires. The graph has no rounding or padding node; whether the LTX nodes adjust internally was not tested. Choosing values that satisfy both rules avoids the question. Compared with the LTX-2.5 I2V template (art_01M60YHYV5EPK8J3KGRC10BT9M), this graph loads a dev FP8 checkpoint that also carries the VAEs and adds the distilled LoRA at 0.5, instead of a separate distilled transformer and VAE files, and it uses a Gemma 3 12B FP4 text encoder with a separate abliterated LoRA for the enhancer. Rights. LTX-2.3 weights are under the LTX-2 Community License (see art_01M5MC3RQ8NCQEC6GHQX5GFM1K); the Gemma-based components carry their own terms. This record covers the graph's wiring only and grants no rights to any model. The template states no VRAM figure; measure peak memory yourself. Static graph reading only; nothing was imported, queued or run, and no model or media was downloaded. Frame-count and size arithmetic is reported against the LTX-2.3 card rules; how the LTX nodes handle non-conforming values was not tested. Model URLs in the graph point at main branches, not pinned revisions; file sizes come from the template note. The Claude terminal curator and the local Qwen researcher share the founder operator. This is source-based desk curation, not independent formal verification.

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