AgentSkillsCN

Photo To Slack Emoji

照片转 Slack 表情符号

SKILL.md

Photo to Slack Emoji Converter & Image Editor

Transform any photo into a classic Slack-optimized emoji using Google's Nano Banana Pro (Gemini 3 Pro Image) model with automatic subject identification and style transformation. NEW: Edit existing images with natural language prompts!

When to Use This Skill

Use this skill when:

  • •Converting photos into Slack custom emojis
  • •Editing existing images/emojis (add hats, change colors, add accessories, etc.)
  • •Creating icon-style representations of people, pets, objects, or concepts
  • •Need automatic subject identification and isolation
  • •Transforming photos to match classic emoji aesthetics (flat, simple, expressive)
  • •Ensuring Slack's strict 64KB file size and dimension requirements are met

Overview

This skill combines:

  1. •Google Nano Banana Pro (Gemini 3 Pro Image) - AI-powered subject identification, style transformation, and image editing with superior quality
  2. •Slack Emoji Validators - Ensures compliance with Slack's 64KB limit and optimal dimensions
  3. •Automatic Optimization - Color quantization, compression, and size validation

Two Main Workflows

1. Photo-to-Emoji Conversion (Original)

code
Photo Input → Gemini Identifies Subject → Transform to Emoji Style → Optimize for Slack → Validate

2. Image Editing (NEW!)

code
Existing Image → Natural Language Edit Prompt → Gemini Edits Image → Optimize (optional) → Save

How It Works

code
Photo Input → Gemini Identifies Subject → Transform to Emoji Style → Optimize for Slack → Validate

Workflow Steps:

  1. •Upload photo - Provide path to source image
  2. •AI identifies subject - Gemini's visual reasoning determines the main subject
  3. •Style transformation - Converts to emoji/icon/sticker style with descriptive prompt
  4. •Optimization - Reduces to 128x128, limits colors to 32-48, compresses to <64KB
  5. •Validation - Confirms Slack requirements are met

Quick Start

Basic Photo-to-Emoji Usage

python
from core.photo_to_emoji import convert_photo_to_emoji

# Convert a photo to a Slack emoji
convert_photo_to_emoji(
    input_path="~/Downloads/my_cat.jpg",
    output_path="~/Desktop/cat_emoji.png",
    style="classic_emoji",
    description="happy cat face"  # Optional: helps guide transformation
)

NEW: Image Editing Usage

IMPORTANT: Never override existing generated images. Always use a different output filename to preserve the original. Iterative editing works best when you can compare versions.

bash
# Command line (easiest way)
python edit_image.py input.jpg output.png "add a party hat"
python edit_image.py cat_emoji.png cat_with_sunglasses.png "add cool sunglasses" --optimize

# WRONG: Don't overwrite the original
# python edit_image.py cat_emoji.png cat_emoji.png "edit" ❌

# CORRECT: Use a new filename
# python edit_image.py cat_emoji.png cat_emoji_edited.png "edit" ✅

# Python API
from core.gemini_client import GeminiImageClient

client = GeminiImageClient()

# Edit an existing image
with open("cat_emoji.png", "rb") as f:
    image_data = f.read()

edited_data = client.edit_image(
    image_data=image_data,
    mime_type="image/png",
    edit_prompt="add a party hat to the cat"
)

# Always save to a NEW filename
with open("cat_with_hat.png", "wb") as f:
    f.write(edited_data)

Advanced Usage with Custom Styles

python
convert_photo_to_emoji(
    input_path="~/Downloads/portrait.jpg",
    output_path="~/Desktop/person_emoji.png",
    style="flat_icon",
    description="friendly person waving",
    custom_prompt="Transform this photo into a simple, flat design icon with bold outlines, minimal details, solid colors, and a white background. Focus on the subject's key features and expression."
)

Available Styles

1. classic_emoji (Recommended for most use cases)

  • •Round, expressive, classic emoji aesthetic
  • •Simplified features with bold outlines
  • •High contrast, vibrant colors
  • •Perfect for faces, animals, and expressive subjects

Example prompt template:

code
Transform this photo into a classic emoji style: round shape, simplified features,
bold outlines, expressive and friendly, vibrant yellow/warm tones, minimal shading,
white or transparent background. Focus on the subject's main expression.

2. flat_icon

  • •Minimalist, flat design
  • •Simple geometric shapes
  • •Solid colors without gradients
  • •Best for objects, logos, symbols

Example prompt template:

code
Transform this photo into a flat, minimalist icon: simple geometric shapes,
solid colors, no gradients, bold clean outlines, modern flat design aesthetic,
white background. Capture the essence of the subject with minimal detail.

3. kawaii_sticker

  • •Cute, playful, Japanese kawaii aesthetic
  • •Rounded features, large eyes
  • •Pastel or vibrant colors
  • •Best for animals, characters, food

Example prompt template:

code
Transform this photo into a kawaii-style sticker: cute and playful, rounded features,
large expressive eyes, simple cel-shading, vibrant color palette, bold clean outlines,
white background. Make it adorable and friendly.

4. pixel_art

  • •Retro 8-bit/16-bit pixel art style
  • •Chunky pixels, limited color palette
  • •Nostalgic gaming aesthetic
  • •Best for characters, objects, icons

Example prompt template:

code
Transform this photo into pixel art: 16x16 or 32x32 pixel style, retro 8-bit aesthetic,
limited color palette (8-16 colors), chunky pixels, clear subject outline,
simple shading, transparent or solid background.

5. custom

  • •Provide your own transformation prompt
  • •Full control over style description
  • •Use for unique or specific aesthetic needs

API Configuration

Setting up Google Gemini API Key

You'll need a Google Gemini API key to use this skill.

  1. •Get API Key: Visit Google AI Studio
  2. •Set Environment Variable:
    bash
    export GEMINI_API_KEY="your-api-key-here"
  3. •Or provide directly in code:
    python
    convert_photo_to_emoji(
    input_path="photo.jpg",
    output_path="emoji.png",
    api_key="your-api-key-here"
)

API Costs

Google Gemini 2.5 Flash Image pricing:

  • •$30 per 1 million output tokens
  • •Each image = 1290 tokens (flat rate up to 1024x1024px)
  • •~$0.039 per image generated

Very cost-effective for emoji creation!

Slack Requirements

Emoji Specifications (Strict)

  • •Max file size: 64KB (strict enforcement)
  • •Optimal dimensions: 128x128 pixels
  • •Recommended colors: 32-48 colors maximum
  • •Format: PNG with transparency support

Validation

The skill automatically validates and optimizes for these requirements:

python
from core.validators import validate_slack_emoji

# After conversion, validate
is_valid, report = validate_slack_emoji("emoji.png")

if is_valid:
    print("✅ Ready to upload to Slack!")
else:
    print(f"❌ Issues: {report}")

Examples

Example 1: Pet Photo to Emoji

python
# Convert a dog photo to a happy emoji
convert_photo_to_emoji(
    input_path="~/Photos/my_dog.jpg",
    output_path="~/Desktop/happy_dog_emoji.png",
    style="classic_emoji",
    description="happy golden retriever smiling"
)

Result: A round, simplified emoji-style dog face with expressive eyes and a big smile.

Example 2: Person Portrait to Icon

python
# Convert a headshot to a professional icon
convert_photo_to_emoji(
    input_path="~/Photos/headshot.jpg",
    output_path="~/Desktop/person_icon.png",
    style="flat_icon",
    description="professional person with glasses"
)

Result: A minimalist, flat design icon representation of the person.

Example 3: Food Photo to Kawaii Sticker

python
# Convert a pizza photo to cute sticker
convert_photo_to_emoji(
    input_path="~/Photos/pizza.jpg",
    output_path="~/Desktop/kawaii_pizza.png",
    style="kawaii_sticker",
    description="cute pizza slice with happy face"
)

Result: A kawaii-style pizza slice with adorable features.

Example 4: Batch Conversion

python
from core.photo_to_emoji import batch_convert

# Convert multiple photos at once
photos = [
    {"input": "cat.jpg", "output": "cat_emoji.png", "description": "happy cat"},
    {"input": "dog.jpg", "output": "dog_emoji.png", "description": "excited dog"},
    {"input": "bird.jpg", "output": "bird_emoji.png", "description": "singing bird"}
]

results = batch_convert(photos, style="classic_emoji")

Advanced Features

Custom Prompts

For maximum control, provide your own transformation prompt:

python
convert_photo_to_emoji(
    input_path="photo.jpg",
    output_path="emoji.png",
    style="custom",
    custom_prompt="""
    Transform this photo into a vintage cartoon style from the 1930s:
    thick black outlines, limited color palette (black, white, red, yellow),
    exaggerated features, bouncy and animated appearance, white background.
    """
)

Size Optimization Strategies

If your emoji exceeds 64KB after conversion:

python
from core.optimizer import aggressive_optimize

# Try aggressive optimization
aggressive_optimize(
    input_path="emoji.png",
    output_path="emoji_optimized.png",
    target_size_kb=60,  # Leave buffer below 64KB
    strategies=["reduce_colors", "reduce_dimensions", "compress_png"]
)

Preview Before Upload

python
from core.preview import preview_emoji

# Preview how it will look in Slack
preview_emoji("emoji.png", sizes=[16, 32, 64, 128])

Shows how the emoji appears at different sizes (Slack displays emojis at various scales).

Troubleshooting

Issue: File size exceeds 64KB

Solutions:

  1. •Use fewer colors: max_colors=32 instead of 48
  2. •Simplify the style: "flat_icon" compresses better than "kawaii_sticker"
  3. •Reduce detail in description: Less detail = simpler image = smaller file
  4. •Use aggressive optimization (see Advanced Features)

Issue: Subject not identified correctly

Solutions:

  1. •Provide more specific description parameter
  2. •Crop photo to focus on main subject before conversion
  3. •Use better-lit, clearer source photo
  4. •Try a custom prompt with explicit subject description

Issue: Style doesn't match expectation

Solutions:

  1. •Try different style presets (flat_icon vs classic_emoji)
  2. •Use custom_prompt for precise control
  3. •Add more descriptive terms to description parameter
  4. •Review style examples in /templates/style_examples.md

Issue: API authentication fails

Solutions:

  1. •Verify GEMINI_API_KEY environment variable is set
  2. •Check API key is valid at Google AI Studio
  3. •Ensure no extra spaces or quotes in API key
  4. •Try providing api_key parameter directly

File Structure

code
~/.claude/skills/photo-to-slack-emoji/
├── skill.md                    # This file
├── core/
│   ├── photo_to_emoji.py      # Main conversion logic
│   ├── gemini_client.py       # Gemini API wrapper
│   ├── optimizer.py           # Image optimization utilities
│   ├── validators.py          # Slack requirement validators
│   └── preview.py             # Preview utilities
├── templates/
│   ├── style_prompts.json     # Pre-defined style templates
│   └── style_examples.md      # Visual style guide
└── references/
    ├── gemini-api-docs.md     # Gemini API documentation
    └── slack-emoji-specs.md   # Slack emoji specifications

Dependencies

bash
# Required packages
pip install pillow google-genai requests

# Optional for advanced features
pip install imageio numpy

Best Practices

  1. •Start with high-quality photos - Better input = better output
  2. •Use descriptive filenames - Helps with organization in Slack
  3. •NEVER override existing generated images - Always save edits to new filenames to preserve originals
  4. •Test at multiple sizes - Preview before uploading to ensure clarity
  5. •Keep it simple - Simpler styles compress better and meet size limits
  6. •Provide context - Use the description parameter to guide transformation
  7. •Batch process - Convert multiple photos at once for efficiency
  8. •Iterative editing - Make small edits and save each version with descriptive names (e.g., cat_v1.png, cat_v2_hat.png, cat_v3_final.png)

Limitations

  • •API rate limits - Google Gemini has rate limits (check your quota)
  • •Subject complexity - Very complex subjects may not simplify well
  • •Background removal - Gemini does its best, but manual editing may improve results
  • •Transparent backgrounds - Not always perfect; may need manual cleanup
  • •Text in photos - May not preserve text accurately in emoji transformation

Related Skills

  • •slack-gif-creator - Create animated GIFs for Slack
  • •canvas-design - Design custom graphics from scratch
  • •firecrawl-mcp - Scrape emoji images from web for reference

What's Next

After creating your emoji:

  1. •

    Upload to Slack:

    • •Go to Slack workspace settings
    • •Click "Customize" → "Emoji"
    • •Upload your PNG file
    • •Give it a memorable name like :my_cat: or :happy_dog:
  2. •

    Share with team:

    • •Emojis are available to entire workspace
    • •Use in messages, reactions, and status updates
  3. •

    Create variations:

    • •Try different styles for the same photo
    • •Experiment with descriptions for different expressions
    • •Build an emoji library for your team

Feedback & Support

This skill uses:

For issues or suggestions, check the skill's GitHub repository or the Claude Code skills directory.