> ## Documentation Index > Fetch the complete documentation index at: https://docs.platform.decart.ai/llms.txt > Use this file to discover all available pages before exploring further. # Prompting Guide > How to write effective prompts for VTON 3.5 — principles, examples, and common mistakes for every try-on. VTON 3.5 applies garments and accessories from a reference image onto a person. A strong prompt tells the model what item or outfit to apply, where it belongs, and which visible garment details matter. Write the prompt like clear styling direction: name the item, describe what it looks like, and avoid asking for unrelated changes. ## At a glance | ✅ Do | ❌ Don't | | --------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------- | | `"Substitute the upper body garment with a grey sleeveless crew-neck t-shirt featuring a single chest pocket with a small logo."` | `"Make me fashionable."` — too vague | | `"Substitute the footwear with white low-top leather sneakers with a clean toe box and thin rubber sole."` | `"Change the background."` — unrelated change | | `"Add a black thick ribbed-knit beanie with a folded cuff and a small white brand label to the outfit."` | `"Add the [Brand name] logo."` — inventing a detail not visible in the reference | ## Core prompting principles ### 1. Use one clear action Each prompt should focus on one try-on action. Use **substitute** when an existing clothing region should be replaced: * “**Substitute** the upper body garment with a cropped black leather jacket.” * “**Substitute** the lower body garment with wide-leg white tailored trousers.” * “**Substitute** the outfit with a red sleeveless midi dress.” Use **add** when the item sits on top of the existing outfit and does not replace clothing: * “**Add** a black ribbed-knit beanie to the outfit.” * “**Add** a tan leather shoulder bag to the outfit.” * “**Add** a gold pendant necklace to the outfit.” Avoid mixing actions in one prompt, such as replacing a jacket and adding a bag at the same time. ### 2. Name the region being changed Be specific about what part of the outfit should change. | Region to change | Start the prompt with | | --------------------------------------------------- | --------------------------------------------------------- | | Tops, jackets, coats, hoodies, shirts, and sweaters | `"Substitute the upper body garment with ."` | | Pants, skirts, shorts, and other bottoms | `"Substitute the lower body garment with ."` | | Dresses, jumpsuits, matching sets, or full looks | `"Substitute the outfit with ."` | | Shoes | `"Substitute the footwear with ."` | | Hats | `"Substitute the hat with ."` | | Necklaces | `"Substitute the necklace with ."` | | Accessories to add on top | `"Add to the outfit."` | ### 3. Let the reference image lead The reference image is the source of truth for the garment. Describe what it actually shows, explicitly — not a new imagined version of it. Good prompts describe the visible item directly: * “Substitute the upper body garment with **a dark green hooded jacket**.” * “Substitute the lower body garment with **white tailored trousers**.” * “Add **a black ribbed beanie with a folded cuff** to the outfit.” Avoid relying on vague phrases: * “Use this.” * “Make it stylish.” * “Give me the same vibe.” ### 4. Describe visible garment details VTON works best when the prompt includes concrete fashion details. Describe what can actually be seen. Useful details include: * Color * Fabric or material * Garment type * Fit or silhouette * Length * Sleeves * Neckline or collar * Closures, such as zipper, buttons, snaps, or drawstrings * Pockets * Texture * Pattern * Visible logo, graphic, or brand text Examples: * “Substitute the upper body garment with **a dark green hooded jacket, zipped closed, with large front utility pockets and a small white logo on the left chest**.” * “Substitute the lower body garment with **oversized burnt orange sherpa fleece trousers with a drawstring waistband**.” * “Add **a black thick ribbed-knit beanie with a folded cuff and a small white brand label** to the outfit.” Do not invent logos, text, or details that are not visible in the reference image. ### 5. Say whether garments are open or closed For garments with buttons, zippers, or front openings, include how they are worn. This matters for: * Jackets * Coats * Cardigans * Blazers * Vests * Dress shirts * Zip hoodies * Button-up garments Examples: * “Substitute the upper body garment with a black blazer, **worn open on top of a white crew-neck t-shirt**.” * “Substitute the upper body garment with a navy zip-up hoodie, **zipped closed**.” * “Substitute the outfit with a **closed** two-button black blazer, a black ribbed turtleneck sweater, and white tailored trousers.” If the garment is open over another visible layer, describe the base layer too. ## Strong prompt examples * “Substitute the upper body garment with a grey sleeveless crew-neck t-shirt featuring a single chest pocket with a small logo.” * “Substitute the outfit with a closed two-button black blazer, a black ribbed turtleneck sweater, and white tailored trousers.” * “Substitute the lower body garment with oversized wide-leg burnt orange sherpa fleece trousers featuring a drawstring waistband.” * “Substitute the footwear with white low-top leather sneakers with a clean toe box and thin rubber sole.” * “Add a black thick ribbed-knit beanie with a folded cuff and a small white brand label to the outfit.” ## Common mistakes **Being too vague:** * “Make me fashionable.” * “Use the reference.” * “Try this look.” **Requesting unrelated changes:** * “Change my face.” * “Make me taller.” * “Change the background.” **Inventing details:** * “Add the \[Brand name] logo,” unless the logo is clearly visible. * “Make it silk,” if the reference does not show silk. The best VTON prompts are short, visual, and specific: one action, one target region, and a faithful description of the visible garment. ## Writing prompts with an AI assistant If you would rather not write the prompt yourself, a chat assistant such as ChatGPT, Claude, or Gemini can turn a garment photo into a ready-to-use prompt. Open the assistant and upload the garment image (a screenshot from a store page works too). Also upload a photo of the person who will wear it — this helps the assistant name the region correctly (for example, "the upper body garment"). Paste an instruction like the one below, then copy the result into VTON 3.5. ```text Prompt to paste wrap theme={null} Look at the attached garment image and write a single virtual try-on prompt. Start it with "Substitute the upper body garment with…" (or "Add … to the outfit" for accessories). Describe only what is visible: color, fabric, garment type, fit, length, sleeves, neckline, closures, pockets, texture, pattern, and any visible logo. Do not invent details that are not shown. Keep it to one sentence. ``` Always review the result before using it — check that every detail actually appears in the image, and delete anything the assistant guessed. ## Preparing a clean garment image VTON 3.5 works best from a clean garment image: just the item, on a plain background, with no one wearing it. Photos from fashion websites usually show a model, a background, and props instead. You can create a clean version with an image-generating assistant (for example, ChatGPT, Gemini, or another image tool): Add the source photo to the assistant. Ask the tool to isolate the garment on a plain background, for example: ```text Prompt to paste wrap theme={null} Extract just the [garment, e.g. green hooded jacket] from this photo and place it on a plain white background. Keep the garment's exact color, shape, and details. Remove the person, the background, and any props. ``` Use the cleaned image as your reference, paired with a descriptive prompt. Keep the garment's real color and details — do not let the tool restyle or "improve" the item, because VTON reproduces what the reference shows.