chart-image

Generate line, bar, and area PNG charts from JSON data with Vega-Lite.

1|Updated Feb 1, 2026
One-click install
npx skills add https://github.com/xukrutdonut/openclaw-skills --skill chart-image
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: chart-image
Source: https://github.com/xukrutdonut/openclaw-skills/tree/main/chart-image
Command: npx skills add https://github.com/xukrutdonut/openclaw-skills --skill chart-image

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires vega, vega-lite, sharp, and includes scripts (resource) components.

What problem does it solve?

chart-image provides a lightweight, server-friendly way to generate publication-quality PNG charts from data without relying on browser-based rendering or external chart services, enabling automated reporting and dashboards.

Core Features & Use Cases

  • Chart generation: Produce line, bar, and area charts from JSON data for reports and monitoring dashboards.
  • Headless rendering: Runs in server/VPS environments without a browser.
  • Output formats: Exports PNG images using Vega-Lite via Node.js and sharp.
  • Use Case: Generate a daily KPI chart from a JSON feed and save it to /tmp/chart.png for automatic email reports.

Quick Start

Use the chart-image skill to generate a simple line chart from sample data: node /data/clawd/skills/chart-image/scripts/chart.mjs --type line --data '[{"x":"Jan","y":10},{"x":"Feb","y":12}]' --output /tmp/chart.png

Frequently Asked Questions about chart-image

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I generate PNG charts from JSON data in a Node.js server environment?▼

To generate PNG charts from JSON data in a Node.js server environment, you can use a headless rendering script that processes JSON inputs with Vega-Lite and Sharp to produce offline PNG outputs without needing a browser.

Can I create bar and line charts for automated reports without a browser?▼

Yes, you can create bar, line, and area charts for automated reports without a browser by running a Node.js script headlessly on a server or VPS environment to render visualizations from JSON data feeds.

Does this chart generation approach work for headless server and VPS deployments?▼

Yes, this chart generation approach works for headless server and VPS deployments by relying entirely on Node.js with Vega-Lite and Sharp to render publication-quality visualizations offline without any browser dependencies.

What is the best way to render publication-quality visualizations offline from JSON?▼

The best way to render publication-quality visualizations offline from JSON is using a server-friendly Node.js script that leverages Vega-Lite for chart specification and Sharp to export crisp PNG images directly to your file system.

Do I need Vega-Lite and Sharp to output PNG images from my monitoring dashboard data?▼

Yes, you need Vega-Lite and Sharp dependencies in your Node.js environment to parse JSON data and process the resulting PNG image outputs for your monitoring dashboards and automated email reports.