remove-background（删除背景）

Remove Background — Transparent PNGs & Cutouts with RMBG 2.0

Remove the background from any image and get a transparent PNG. Powered by Bria's RMBG 2.0 model — commercially safe, royalty-free, production-ready background removal and foreground segmentation.

When to Use This Skill

Use this skill when the user wants to:

• Remove a background — "remove the background", "make the background transparent", "delete the background"
• Create a transparent PNG — "give me a PNG with no background", "transparent version", "cutout"
• Create a cutout — "cut out the person", "cutout of the product", "photo cutout", "image cutout"
• Extract the foreground subject — "isolate the product", "extract the object", "foreground extraction"
• Product cutout for e-commerce — "product photo with transparent background", "packshot cutout", "catalog cutout image"
• Portrait and headshot cutout — "remove background from headshot", "portrait with no background"
• Batch background removal — "remove backgrounds from all these images", "process in bulk"
• Image segmentation — "segment the foreground", "separate foreground and background", "foreground segmentation"
• Prepare cutouts for compositing — "I need a cutout to paste onto another image", "layer separation"
• Background eraser — "erase the background", "background eraser tool", "clean background removal"

When NOT to Use This Skill

For other image operations, use the bria-ai skill instead:

• Replace background with a new scene → bria-ai (replace_background)
• Blur background → bria-ai (blur_background)
• Generate images from text → bria-ai (generate)
• Edit images with instructions → bria-ai (edit)

This skill does one thing: remove backgrounds to produce transparent PNGs and cutouts.

Setup — Authentication

Before making any API call, you need a valid Bria access token.

Step 1: Check for existing credentials

if [ -f ~/.bria/credentials ]; then
  BRIA_ACCESS_TOKEN=$(grep '^access_token=' "$HOME/.bria/credentials" | cut -d= -f2-)
  BRIA_API_KEY=$(grep '^api_token=' "$HOME/.bria/credentials" | cut -d= -f2-)
fi
if [ -z "$BRIA_ACCESS_TOKEN" ]; then
  echo "NO_CREDENTIALS"
elif [ -n "$BRIA_API_KEY" ]; then
  echo "READY"
else
  echo "CREDENTIALS_FOUND"
fi

If the output is READY, skip straight to making API calls — no introspection needed. If the output is CREDENTIALS_FOUND, skip to Step 3. If the output is NO_CREDENTIALS, proceed to Step 2.

Step 2: Authenticate via device authorization

Start the device authorization flow:

2a. Request a device code:

DEVICE_RESPONSE=$(curl -s -X POST "https://engine.prod.bria-api.com/v2/auth/device/authorize" \
  -H "Content-Type: application/json")
echo "$DEVICE_RESPONSE"

Parse the response fields:

• device_code — used to poll for the token (keep this, don't show to user)
• user_code — the code the user must enter (e.g. BRIA-XXXX)
• interval — seconds between poll attempts

2b. Show the user a single sign-in link. Tell them exactly this — nothing more:

Connect your Bria account: Click here to sign in Your code is {user_code} — it's already filled in.

Do NOT show two links. Do NOT show the raw URL separately. Do NOT use verification_uri from the API response. Keep it to one clickable link.

2c. Poll for the token. After showing the user the code, immediately start polling. Try up to 60 times with the given interval (default 5 seconds):

for i in $(seq 1 60); do
  TOKEN_RESPONSE=$(curl -s -X POST "https://engine.prod.bria-api.com/v2/auth/token" \
    -d "grant_type=urn:ietf:params:oauth:grant-type:device_code" \
    -d "device_code=$DEVICE_CODE")
  ACCESS_TOKEN=$(printf '%s' "$TOKEN_RESPONSE" | sed -n 's/.*"access_token" *: *"\([^"]*\)".*/\1/p')
  if [ -n "$ACCESS_TOKEN" ]; then
    BRIA_ACCESS_TOKEN="$ACCESS_TOKEN"
    REFRESH_TOKEN=$(printf '%s' "$TOKEN_RESPONSE" | sed -n 's/.*"refresh_token" *: *"\([^"]*\)".*/\1/p')
    mkdir -p ~/.bria
    printf 'access_token=%s\nrefresh_token=%s\n' "$BRIA_ACCESS_TOKEN" "$REFRESH_TOKEN" > "$HOME/.bria/credentials"
    echo "AUTHENTICATED"
    break
  fi
  sleep 5
done

If the output contains AUTHENTICATED, proceed to Step 3. Otherwise the code expired — start over from Step 2a.

Do not proceed with any API call until authentication is confirmed.

Step 3: Verify billing status and resolve API key

Introspect the bearer token to check billing status and obtain the real API key for Bria API calls:

INTROSPECT=$(curl -s -X POST "https://engine.prod.bria-api.com/v2/auth/token/introspect" \
  -d "token=$BRIA_ACCESS_TOKEN")
BILLING_STATUS=$(printf '%s' "$INTROSPECT" | sed -n 's/.*"billing_status" *: *"\([^"]*\)".*/\1/p')
if [ "$BILLING_STATUS" = "blocked" ]; then
  BILLING_MSG=$(printf '%s' "$INTROSPECT" | sed -n 's/.*"billing_message" *: *"\([^"]*\)".*/\1/p')
  echo "BILLING_ERROR: $BILLING_MSG"
fi
ACTIVE=$(printf '%s' "$INTROSPECT" | sed -n 's/.*"active" *: *\([^,}]*\).*/\1/p' | tr -d ' ')
if [ "$ACTIVE" = "false" ]; then
  # Clear stale tokens so re-auth starts fresh (credentials file is re-created in Step 2c)
  printf '' > "$HOME/.bria/credentials"
  echo "TOKEN_EXPIRED"
fi
BRIA_API_KEY=$(printf '%s' "$INTROSPECT" | sed -n 's/.*"api_token" *: *"\([^"]*\)".*/\1/p')
if [ -n "$BRIA_API_KEY" ]; then
  grep -v '^api_token=' "$HOME/.bria/credentials" > "$HOME/.bria/credentials.tmp" 2>/dev/null || true
  printf 'api_token=%s\n' "$BRIA_API_KEY" >> "$HOME/.bria/credentials.tmp"
  mv "$HOME/.bria/credentials.tmp" "$HOME/.bria/credentials"
fi

Interpret the output:

• If it prints BILLING_ERROR:... — relay the message to the user exactly as shown and stop. Do not make any API calls.
• If it prints TOKEN_EXPIRED — the session is no longer valid. Tell the user their session expired and restart from Step 2.
• Otherwise, BRIA_API_KEY now contains the real API key and is cached for future calls. Proceed to the next section.

How to Remove a Background

Use bria_call for the API call. It handles URL passthrough, local file base64 encoding, JSON construction, the API call, and async polling — all in a single function call. The API key is auto-loaded from ~/.bria/credentials.

source ~/.agents/skills/remove-background/references/code-examples/bria_client.sh

# Remove background from a local file — get transparent PNG cutout
RESULT_URL=$(bria_call /v2/image/edit/remove_background "/path/to/image.png")
echo "$RESULT_URL"  # → https://...transparent.png

# Remove background from a URL — get transparent PNG cutout
RESULT_URL=$(bria_call /v2/image/edit/remove_background "https://example.com/photo.jpg")
echo "$RESULT_URL"  # → https://...transparent.png

That's it. One function call. The result is a URL to a transparent PNG with the background removed.

Input

• Local file path — any image file (JPEG, PNG, WEBP). Automatically base64-encoded and uploaded.
• Image URL — any publicly accessible image URL. Passed directly to the API.

Supported formats: JPEG, PNG, WEBP. Supports CMYK and RGBA input.

Output

A URL to a PNG with transparency — the background is fully removed, leaving only the foreground subject with an alpha channel.

Download the result to save it locally:

curl -sL "$RESULT_URL" -o output.png

Examples

Product cutout for e-commerce

Create a transparent product cutout for online stores, catalogs, and marketplaces:

source ~/.agents/skills/remove-background/references/code-examples/bria_client.sh
RESULT_URL=$(bria_call /v2/image/edit/remove_background "/path/to/product.jpg")
curl -sL "$RESULT_URL" -o product_cutout.png
echo "Transparent product cutout saved to product_cutout.png"

Portrait and headshot background removal

Remove backgrounds from headshots and portraits for team pages, social profiles, and compositing:

source ~/.agents/skills/remove-background/references/code-examples/bria_client.sh
RESULT_URL=$(bria_call /v2/image/edit/remove_background "https://example.com/headshot.jpg")
curl -sL "$RESULT_URL" -o headshot_cutout.png

Batch background removal

Process entire directories — remove backgrounds in bulk for e-commerce catalogs and asset pipelines:

source ~/.agents/skills/remove-background/references/code-examples/bria_client.sh
mkdir -p cutouts
for img in images/*.{jpg,png,webp}; do
  [ -f "$img" ] || continue
  name=$(basename "${img%.*}")
  RESULT_URL=$(bria_call /v2/image/edit/remove_background "$img")
  if [ -n "$RESULT_URL" ] && [ "$RESULT_URL" != "ERROR"* ]; then
    curl -sL "$RESULT_URL" -o "cutouts/${name}_cutout.png"
    echo "Done: $name"
  else
    echo "Failed: $name" >&2
  fi
done

Extract foreground subject for compositing

Segment and extract the foreground from any photo to create a cutout for layering and compositing:

source ~/.agents/skills/remove-background/references/code-examples/bria_client.sh
RESULT_URL=$(bria_call /v2/image/edit/remove_background "/path/to/scene.jpg")
curl -sL "$RESULT_URL" -o foreground_cutout.png

How RMBG 2.0 Works

1. You provide an image (local file path or URL)
2. bria_call sends it to Bria's RMBG 2.0 background removal endpoint
3. The RMBG model performs foreground-background segmentation with pixel-level accuracy
4. Background pixels become transparent (alpha = 0)
5. You get back a PNG URL with full transparency — a clean cutout

RMBG 2.0 handles complex edges with production-grade accuracy:

• Hair and fur — fine strands and wispy edges preserved
• Transparent and semi-transparent objects — glass, veils, smoke
• Complex backgrounds — busy scenes, gradients, similar colors
• Multiple subjects — groups of people, product arrangements
• Fine details — jewelry, lace, intricate patterns

Additional Resources

• API Endpoints Reference — Full endpoint documentation with request/response format
• Shell Client (bria_client.sh) — Single-function helper: bria_call handles auth, base64, JSON, polling

Related Skills

• bria-ai — Full Bria API access: generate images, edit photos, replace/blur backgrounds, upscale, restyle, product photography, and 20+ more endpoints
• image-utils — Post-processing with Python Pillow: resize, crop, composite, watermarks, format conversion