> ## Documentation Index > Fetch the complete documentation index at: https://docs.vivix.ai/llms.txt > Use this file to discover all available pages before exploring further. # Prepare the first image Your starting image sets the avatar’s appearance and gives it room to move. Choose a **clear face with space for the gestures you want** before fine-tuning the outfit or background. ## 1. Choose an image that fits the session For **9:16** portrait output, start with a portrait image of the same ratio; match a landscape image to landscape output. A **chest-up to waist-up** shot works well for conversation. A knee-up shot can give the hands more room, as long as the eyes and mouth stay clear. Keep the hands fully inside the frame rather than cropping them at the wrists. As a quick check, divide the **width of the face box by the image’s shorter edge**: image width in portrait, image height in landscape. This is a selection guide, not an upload limit. * **Start here: 25% or more.** A chest-up, waist-up, or close knee-up image keeps the face clear and leaves room for gestures. * **Try a closer image: below 25%.** Full-body or distant shots can lose facial detail during conversation. A face-only crop can also be too tight for waving or handling objects. Keep both eyes and the mouth visible; avoid hair, hands, heavy backlighting, or other people obscuring the face. ## 2. Compare two images

Good	Less suitable

Face and hands are clear, with room for gestures.	Full outfit is visible, but the face is small for close conversation.

## 3. Add an image description when useful `source_images[].description` is **optional**. Add a short English description when you need to make the visible outfit, pose, or hand-object relationship explicit. Describe what is **already in the image**, not an action you want the avatar to perform later. ```text wrap theme={null} A man with short dark hair faces the camera in a knee-up portrait. He wears a black T-shirt and dark pants. Both hands are empty and fully visible at his sides. His eyes and mouth are clear. The background is a softly lit gym. ``` Add the image under `avatars[0].visual.source_images` when creating a Session. This fragment shows only the image fields; see the [Quickstart](/streaming-avatar/get-started/quickstart) for a full request. ```json wrap theme={null} { "visual": { "source_images": [ { "source_image_id": "portrait", "url": "https://YOUR_PUBLIC_HOST/portrait.jpg", "media_type": "image/jpeg", "description": "A man with short dark hair faces the camera in a knee-up portrait. He wears a black T-shirt and dark pants. Both hands are empty and fully visible at his sides." } ] } } ``` Use a directly accessible image URL. The example includes `description`; adapt it to the image you use, or omit the field.