设计与多媒体

Image Utils

基于 Pillow 的图像处理工具:缩放、裁剪、水印、格式转换与 Web 优化一次搞定。

它能做什么

基于 Pillow 的工具集,专注意确定性的像素级图像处理。支持从 URL、本地路径、字节流或 base64 加载图片,再进行缩放、裁剪、合成、添加水印、调色与格式转换。提供批处理辅助方法与 Web 交付优化步骤,可直接用于压缩出图。可与 bria-ai 技能搭配,对 AI 生成的图像做后处理。本工具不生成图像、也不做语义层面的编辑——这类任务请交给生成式图像技能。

什么时候用它

  • 批量处理商品图:缩放、加水印并压缩,再上传到网页
  • 把 AI 生成的 PNG 转成多种尺寸的优化 WebP,适配响应式页面
  • 按平台比例(1:1、16:9、9:16)裁剪图片,准备社交媒体素材
  • 给目录图添加文字或 Logo 水印,并加上白边填充

技能文档

Image Utilities

Pillow-based utilities for deterministic pixel-level image operations. Use for resize, crop, composite, format conversion, watermarks, and other standard image processing tasks.

When to Use This Skill

  • Post-processing AI-generated images: Resize, crop, optimize for web after generation
  • Format conversion: PNG ↔ JPEG ↔ WEBP with quality control
  • Compositing: Overlay images, paste subjects onto backgrounds
  • Batch processing: Resize to multiple sizes, add watermarks
  • Web optimization: Compress and resize for fast delivery
  • Social media preparation: Crop to platform-specific aspect ratios

When NOT to Use This Skill — Use bria-ai Instead

This skill handles deterministic pixel-level operations only. For any generative or AI-powered image work, use the bria-ai skill instead:

  • Generating images from text prompts → use bria-ai
  • AI background removal or replacement → use bria-ai
  • AI image editing (inpainting, object removal/addition) → use bria-ai
  • Style transfer or AI-driven visual effects → use bria-ai
  • Creating product lifestyle shots with AI → use bria-ai
  • Image upscaling with AI super-resolution → use bria-ai

Rule of thumb: If the task requires creating new visual content or understanding image semantics, use bria-ai. If the task requires transforming existing pixels (resize, crop, format convert, watermark), use this skill.

If bria-ai is not available, install it with:

npx skills add bria-ai/bria-skill

Quick Reference

OperationMethodDescription
Loadingload(source)Load from URL, path, bytes, or base64
load_from_url(url)Download image from URL
Savingsave(image, path)Save with format auto-detection
to_bytes(image, format)Convert to bytes
to_base64(image, format)Convert to base64 string
Resizingresize(image, width, height)Resize to exact dimensions
scale(image, factor)Scale by factor (0.5 = half)
thumbnail(image, size)Fit within size, maintain aspect
Croppingcrop(image, left, top, right, bottom)Crop to region
crop_center(image, width, height)Crop from center
crop_to_aspect(image, ratio)Crop to aspect ratio
Compositingpaste(bg, fg, position)Overlay at coordinates
composite(bg, fg, mask)Alpha composite
fit_to_canvas(image, w, h)Fit onto canvas size
Bordersadd_border(image, width, color)Add solid border
add_padding(image, padding)Add whitespace padding
Transformsrotate(image, angle)Rotate by degrees
flip_horizontal(image)Mirror horizontally
flip_vertical(image)Flip vertically
Watermarksadd_text_watermark(image, text)Add text overlay
add_image_watermark(image, logo)Add logo watermark
Adjustmentsadjust_brightness(image, factor)Lighten/darken
adjust_contrast(image, factor)Adjust contrast
adjust_saturation(image, factor)Adjust color saturation
blur(image, radius)Apply Gaussian blur
Weboptimize_for_web(image, max_size)Optimize for delivery
Infoget_info(image)Get dimensions, format, mode

Requirements

pip install Pillow requests

Basic Usage

from image_utils import ImageUtils

# Load from URL
image = ImageUtils.load_from_url("https://example.com/image.jpg")

# Or load from various sources
image = ImageUtils.load("/path/to/image.png")         # File path
image = ImageUtils.load(image_bytes)                  # Bytes
image = ImageUtils.load("data:image/png;base64,...")  # Base64

# Resize and save
resized = ImageUtils.resize(image, width=800, height=600)
ImageUtils.save(resized, "output.webp", quality=90)

# Get image info
info = ImageUtils.get_info(image)
print(f"{info['width']}x{info['height']} {info['mode']}")

Resizing & Scaling

# Resize to exact dimensions
resized = ImageUtils.resize(image, width=800, height=600)

# Resize maintaining aspect ratio (fit within bounds)
fitted = ImageUtils.resize(image, width=800, height=600, maintain_aspect=True)

# Resize by width only (height auto-calculated)
resized = ImageUtils.resize(image, width=800)

# Scale by factor
half = ImageUtils.scale(image, 0.5)    # 50% size
double = ImageUtils.scale(image, 2.0)  # 200% size

# Create thumbnail
thumb = ImageUtils.thumbnail(image, (150, 150))

Cropping

# Crop to specific region
cropped = ImageUtils.crop(image, left=100, top=50, right=500, bottom=350)

# Crop from center
center = ImageUtils.crop_center(image, width=400, height=400)

# Crop to aspect ratio (for social media)
square = ImageUtils.crop_to_aspect(image, "1:1")      # Instagram
wide = ImageUtils.crop_to_aspect(image, "16:9")       # YouTube thumbnail
story = ImageUtils.crop_to_aspect(image, "9:16")      # Stories/Reels

# Control crop anchor
top_crop = ImageUtils.crop_to_aspect(image, "16:9", anchor="top")
bottom_crop = ImageUtils.crop_to_aspect(image, "16:9", anchor="bottom")

Compositing

# Paste foreground onto background
result = ImageUtils.paste(background, foreground, position=(100, 50))

# Alpha composite (foreground must have transparency)
result = ImageUtils.composite(background, foreground)

# Fit image onto canvas with letterboxing
canvas = ImageUtils.fit_to_canvas(
    image,
    width=1200,
    height=800,
    background_color=(255, 255, 255, 255),  # White
    position="center"  # or "top", "bottom"
)

Format Conversion

# Convert to different formats
png_bytes = ImageUtils.to_bytes(image, "PNG")
jpeg_bytes = ImageUtils.to_bytes(image, "JPEG", quality=85)
webp_bytes = ImageUtils.to_bytes(image, "WEBP", quality=90)

# Get base64 for data URLs
base64_str = ImageUtils.to_base64(image, "PNG")
data_url = ImageUtils.to_base64(image, "PNG", include_data_url=True)
# Returns: "data:image/png;base64,..."

# Save with format auto-detected from extension
ImageUtils.save(image, "output.png")
ImageUtils.save(image, "output.jpg", quality=85)
ImageUtils.save(image, "output.webp", quality=90)

Watermarks

# Text watermark
watermarked = ImageUtils.add_text_watermark(
    image,
    text="© 2024 My Company",
    position="bottom-right",  # bottom-left, top-right, top-left, center
    font_size=24,
    color=(255, 255, 255, 128),  # Semi-transparent white
    margin=20
)

# Logo/image watermark
logo = ImageUtils.load("logo.png")
watermarked = ImageUtils.add_image_watermark(
    image,
    watermark=logo,
    position="bottom-right",
    opacity=0.5,
    scale=0.15,  # 15% of image width
    margin=20
)

Adjustments

# Brightness (1.0 = original, <1 darker, >1 lighter)
bright = ImageUtils.adjust_brightness(image, 1.3)
dark = ImageUtils.adjust_brightness(image, 0.7)

# Contrast (1.0 = original)
high_contrast = ImageUtils.adjust_contrast(image, 1.5)

# Saturation (0 = grayscale, 1.0 = original, >1 more vivid)
vivid = ImageUtils.adjust_saturation(image, 1.3)
grayscale = ImageUtils.adjust_saturation(image, 0)

# Sharpness
sharp = ImageUtils.adjust_sharpness(image, 2.0)

# Blur
blurred = ImageUtils.blur(image, radius=5)

Transforms

# Rotate (counter-clockwise, degrees)
rotated = ImageUtils.rotate(image, 45)
rotated = ImageUtils.rotate(image, 90, expand=False)  # Don't expand canvas

# Flip
mirrored = ImageUtils.flip_horizontal(image)
flipped = ImageUtils.flip_vertical(image)

Borders & Padding

# Add solid border
bordered = ImageUtils.add_border(image, width=5, color=(0, 0, 0))

# Add padding (whitespace)
padded = ImageUtils.add_padding(image, padding=20)  # Uniform
padded = ImageUtils.add_padding(image, padding=(10, 20, 10, 20))  # left, top, right, bottom

Web Optimization

# Optimize for web delivery
optimized_bytes = ImageUtils.optimize_for_web(
    image,
    max_dimension=1920,  # Resize if larger
    format="WEBP",       # Best compression
    quality=85
)

# Save optimized
with open("optimized.webp", "wb") as f:
    f.write(optimized_bytes)

Integration with Bria AI

Use alongside the bria-ai skill to post-process AI-generated images. Generate or edit images with Bria's API, then use image-utils for resizing, cropping, watermarking, and web optimization.

import requests
from image_utils import ImageUtils

# Generate with Bria AI (see bria-ai skill for full API reference)
response = requests.post(
    "https://engine.prod.bria-api.com/v2/image/generate",
    headers={"api_token": BRIA_API_KEY, "Content-Type": "application/json"},
    json={"prompt": "product photo of headphones", "aspect_ratio": "1:1", "sync": True}
)
image_url = response.json()["result"]["image_url"]

# Download and post-process
image = ImageUtils.load_from_url(image_url)

# Create multiple sizes for responsive images
sizes = {
    "large": ImageUtils.resize(image, width=1200),
    "medium": ImageUtils.resize(image, width=600),
    "thumb": ImageUtils.thumbnail(image, (150, 150))
}

# Save all as optimized WebP
for name, img in sizes.items():
    ImageUtils.save(img, f"product_{name}.webp", quality=85)

Batch Processing Example

from pathlib import Path
from image_utils import ImageUtils

def process_catalog(input_dir, output_dir):
    """Process all images in a directory."""
    output_path = Path(output_dir)
    output_path.mkdir(exist_ok=True)

    for image_file in Path(input_dir).glob("*.{jpg,png,webp}"):
        image = ImageUtils.load(image_file)

        # Crop to square
        square = ImageUtils.crop_to_aspect(image, "1:1")

        # Resize to standard size
        resized = ImageUtils.resize(square, width=800, height=800)

        # Add watermark
        final = ImageUtils.add_text_watermark(resized, "© My Brand")

        # Save optimized
        output_file = output_path / f"{image_file.stem}.webp"
        ImageUtils.save(final, output_file, quality=85)

process_catalog("./raw_images", "./processed")

API Reference

See image_utils.py for complete implementation with docstrings.

常见问题

它能生成或编辑图像吗?
不能。本工具只做确定性的像素级操作。文生图、局部重绘、AI 抠图、AI 超分等任务,应使用 bria-ai 技能。
支持哪些输入来源?
支持从文件路径、原始字节、base64 字符串(可带 data URL 前缀)加载,也可通过 load_from_url 从远程 URL 下载图片。
可以输出哪些格式?
支持 PNG、JPEG、WEBP,可设置压缩质量;to_base64 还能输出 base64 字符串或完整的 data URL。save 方法会根据文件扩展名自动识别格式。

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