Item Change Background

item-change-background — 商品图生成逼真场景图

白底商品图 → 有质感的实拍场景图。商品不动，环境换掉。

关键不是「贴一张背景」，而是接地投影、环境反光、光向一致——这三件事做不到，商品就像浮在背景上的贴纸。

生成效果示例

实际执行的命令：

dlazy gpt-image-2 \
  --prompt 'Place this product into a photorealistic lifestyle scene. Keep the pair of black patent leather derby shoes 100% faithful: same glossy patent finish, same brogue perforation pattern, same lacing, same chunky lug sole, same proportions and camera angle. Replace the plain background with a warm autumn scene: a weathered wooden floor beside a window, a few dry maple leaves, soft late-afternoon side light casting a natural contact shadow under each shoe, blurred indoor background. The shoes must sit believably on the surface with correct perspective and grounded shadows. Photorealistic commercial product photography, no text, no watermark.' \
  --images docs/item-change-background/product-shoes.jpg \
  --size 1024x1024 --quality medium --imageFormat jpeg \
  --save docs/item-change-background/example-output.jpg

输出

example-output.jpg — 1024×1024。鞋的鳄鱼纹压花、雕花孔、白色沿条明线与厚齿底保持不变；背景换成窗边旧木板 + 枫叶，午后侧光在鞋头形成高光，每只鞋下都有接地投影，木纹的暖色被亮面皮革轻微反射。

1、能力边界

不做：不改商品的外形、颜色、材质与 logo；不添加原图没有的商品部件；不生成误导性的使用场景（如非防水产品放进水里）。

2、输入素材规则

生成前先自检这几条硬性约束：

• 大小：20KB ~ 15MB
• 分辨率：大于 400×400
• 格式：jpg / jpeg / png / webp

输入建议

3、让商品「落地」的三条物理约束

这三句几乎决定成败，每次都要写：

1. 接地：sitting believably on the surface with correct perspective and a grounded contact shadow
2. 光向：light direction and colour temperature must match the shading already on the product
3. 反光：[环境元素] subtly reflected on the [商品材质], consistent with the scene

类目 → 合理场景对照

4、工具调用

本技能使用 dLazy 的 gpt-image-2（图像编辑模型；商品换背景的难点是「商品像素不动 + 环境重建 + 物理正确的光影耦合」，需要强区域保持与场景理解）。

调用方式

两种等价写法，选一种。统一入口会自动选后端、失败重试、建目录落盘、估算成本：

# A. 统一入口（推荐）：可切任意后端，加 --dry-run 不计费空跑
node scripts/gen.mjs --task item-change-background \
  --prompt '<见下方 Prompt 模板>' \
  --images <按下表顺序> \
  --save output/item-change-background-<sku>.jpg

# B. 直接用 dLazy CLI（不想引入 Node 依赖时，效果等价）
dlazy gpt-image-2 --prompt '...' --images ... --save output/item-change-background.jpg

参数约定（本技能固定用法）

Command Examples

# basic call: 文生背景
dlazy gpt-image-2 \
  --prompt 'Place this product into a photorealistic lifestyle scene. Keep the product 100% faithful: same shape, colour, material finish and logo. Replace the plain background with a weathered wooden floor beside a window, soft late-afternoon side light casting a natural contact shadow, blurred indoor background. The product must sit believably on the surface with correct perspective and grounded shadows. Photorealistic commercial product photography, no text.' \
  --images docs/item-change-background/product-shoes.jpg \
  --size 1024x1024 --quality medium

# complex call: 上传背景图 + 一个商品铺 4 个场景
SRC=docs/item-change-background/product-shoes.jpg
KEEP='Keep the pair of black crocodile-embossed patent leather derby shoes 100% faithful: same glossy finish, same croc embossing pattern, same brogue perforation, same lacing, same white welt stitching, same chunky lug sole, same proportions and camera angle.'
PHYS='The shoes must sit believably on the surface with correct perspective and a grounded contact shadow under each shoe. Light direction and colour temperature must match the shading already on the product. Photorealistic commercial product photography, no text, no watermark.'
for S in wood street office autumn; do
  case $S in
    wood)   SCENE='on a weathered wooden floor beside a window, soft late-afternoon side light, blurred indoor background' ;;
    street) SCENE='on wet grey cobblestones after rain, reflections in the puddles, overcast diffused light' ;;
    office) SCENE='on a dark polished stone floor in a modern office lobby, cool directional light, glass panels blurred behind' ;;
    autumn) SCENE='on a wooden deck with a few dry maple leaves, warm golden-hour side light' ;;
  esac
  dlazy gpt-image-2 \
    --prompt "Place this product into a photorealistic lifestyle scene. $KEEP Replace the plain background with a scene: $SCENE. $PHYS" \
    --images "$SRC" --size 1024x1024 --quality high --imageFormat jpeg \
    --batch 2 --save "docs/item-change-background/output-sku001-$S.jpg"
done

# 上传背景图的写法：--images 商品图 背景图
dlazy gpt-image-2 \
  --prompt 'Composite the product from image 1 into the scene from image 2. Keep the product 100% faithful. Place it on [具体位置] with correct perspective, a grounded contact shadow, and light direction matching image 2. Blend edges seamlessly; no cut-out halo. Photorealistic, no text.' \
  --images docs/item-change-background/product-shoes.jpg docs/item-change-background/bg.jpg \
  --size 1024x1024 --quality high

# 先估价不真跑
dlazy gpt-image-2 --dry-run --prompt '...' --images a.jpg --size 1024x1024 --quality high

延伸阅读

5、Prompt 模板

Place this product into a photorealistic lifestyle scene.

Keep the [商品品类 + 颜色 + 材质] 100% faithful: same [外形], same [材质光泽],
same [五金/缝线/纹理], same [logo 位置], same proportions and camera angle.

Replace the background with [场景描述：表面 + 环境 + 道具 + 光线].

The product must sit believably on the surface with correct perspective and a
grounded contact shadow. Light direction and colour temperature must match the
shading already on the product. [环境元素] subtly reflected on the [材质].

Photorealistic commercial product photography, no text, no watermark.

按问题追加的修正句

6、执行流程

1. 洗成白底：商品图如带复杂背景，先抠干净。
2. 查类目 → 合理场景（第三节表格），避免物理上不成立的组合。
3. 写商品保真句 → 写场景句 → 写三条物理约束（接地 / 光向 / 反光）。
4. 反光材质用 --quality high。
5. --batch 2~4 出多张挑构图，落盘到 docs/item-change-background/。
6. 质检：是否接地（有没有投影和压痕）、光向是否一致、边缘有没有白边、商品本体是否被改。

7、常见问题

Tips

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