transparent-bglisted

# Transparent background ## The problem (see research 13 + 04) Almost every modern T2I VAE is **RGB-only**. Asking Imagen 3/4 or Gemini 2.5/3 Flash Image for a "transparent logo" triggers one of two failures: 1. **Flat background** — DALL·E 3, Stable Diffusion families render a white/gray background that must be matted. 2. **Checkerboard as RGB pixels** — Gemini/Imagen literally render the gray-and-white 8×8 tile pattern (because Photoshop screenshots in their training data show transparency that way). This is the "weird boxes" users report. **It cannot be fixed by prompting.** ## Fix hierarchy (apply first that fits) ### 1. Route to a native-RGBA provider | Provider | Mechanism | |---|---| | **`gpt-image-1` / `gpt-image-1.5`** | API param `background: "transparent"` + `output_format: "png"` or `"webp"` | | **Ideogram 3 Turbo** | Dedicated `/ideogram-v3/generate-transparent` endpoint; set `rendering_speed: "TURBO"` for Turbo tier | | **Recraft V3** | native SVG output (alpha is trivial); rasterize if raster needed | | **LayerDiffuse on SDXL / Flux** | In-diffusion-loop transparency adapter; better edges than post-matte | ### 2. Post-process matte (for everything else) | Matting model | License | Strength | |---|---|---| | **BiRefNet** | MIT | Default choice 2026; best soft-edge handling | | **BRIA RMBG-2.0** | CC-BY-NC-4.0 (hosted API for commercial) | Best overall quality | | **U²-Net** | Apache-2.0 | Legacy fallback | | **rembg** | wrapper around U²-Net / BiRefNet |