Riverflow V2.6 Pro

Riverflow 2.6 Pro is the flagship model of Sourceful's Riverflow 2.6 lineup, a unified text-to-image and image-to-image family that treats generation as a production workflow: an integrated reasoning model plans multi-step edits and judges candidates before accepting a result, combining that reasoning with a mix of closed and open image diffusion models for accuracy and steerability. Reasoning effort is controllable via the reasoning parameter (low/medium/high/xhigh); higher levels do more editing passes and apply a stricter internal judge.

Riverflow 2.6 adds custom output dimensions: pass `size` as `WIDTHxHEIGHT` (up to 16,384 px per edge, 16.8 megapixels total, 16:1 aspect ratio) instead of a preset, or keep using 1K/2K/4K with an aspect ratio (now including 5:4 and 4:5). It accepts up to 10 input images for editing.

Pricing is dynamic: cost is finalized per job at completion based on billable processing, so it scales with reasoning effort, output size, and editing complexity rather than a fixed per-image rate.

Additional features (via image_config):
- Custom font rendering via font_inputs (max 2) to match brand lettering, spacing, and weight
- Custom scoring via scoring_prompt and scoring_rubric, so the reasoning model evaluates and steers each candidate against the criteria you care about
- Background control via background_mode (original, transparent, solid) and background_hex_color

See the image generation docs for details: https://openrouter.ai/docs/features/multimodal/image-generation

Note: Sourceful imposes a 4.5MB request size limit, therefore it is highly recommended to pass image URLs instead of Base64 data.