fast-thumbnail

fast-thumbnail is a skill for Claude Code from danielrosehill/Claude-Image-Production-Plugin. It costs 56 tokens per session (850 once invoked), scanned A, original, MIT.

A batch thumbnail generator for making small preview images from many originals. It uses vipsthumbnail and can save JPEG, PNG, WebP, or AVIF files without overwriting the originals.

In plain words
What is it for?
Building contact sheets and web galleries, pre-rendering image-browser previews, and shrinking a library into thumbnail-sized copies.
Why use it?
It creates manageable previews quickly when full-size images are too large for galleries, file browsers, sharing, or archives.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the image-production plugin — 29 skills, 19 commands shipped together

Good fit Building contact sheets and web galleries, pre-rendering image-browser previews, and shrinking a library into thumbnail-sized copies.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/danielrosehill/claude-image-production-plugin/fast-thumbnail
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add danielrosehill/Claude-Image-Production-Plugin --skill fast-thumbnail
Clone the repo
git clone --depth 1 https://github.com/danielrosehill/Claude-Image-Production-Plugin

Made for: Claude Code.

Or install image-production, the plugin that ships this one along with the rest of its 29 skills, 19 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fast-thumbnail

README.md
[![agentmods](https://agentmods.dev/badge/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail/github.svg)](https://agentmods.dev/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail)
Your own site
<a href="https://agentmods.dev/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail"><img src="https://agentmods.dev/badge/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fast-thumbnail

Your own site · 80×15
<a href="https://agentmods.dev/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail"><img src="https://agentmods.dev/badge/skills/danielrosehill/claude-image-production-plugin/fast-thumbnail.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 850 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00056 $0.00850
Opus 5 $0.00028 $0.00425
Sonnet 5 $0.00011 $0.00170
Haiku 4.5 $0.00006 $0.00085

Measured 9d ago against content hash 0184962918d0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fast-thumbnail scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/fast-thumbnail/SKILL.md · 63 lines

How it starts

The opening of the file, as written. The whole thing — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fast Thumbnail (vipsthumbnail)

Generate thumbnails at high throughput using vipsthumbnail. Distinct from fast-resize: this is purpose-built for "make small previews of every image in this folder" workflows where output is always a downscale and quality is "good enough for a thumbnail".

When to use

  • Building a contact-sheet / web-gallery / index of an image library.
  • Pre-rendering thumbnails for a UI / filesystem browser.
  • Bulk-shrinking large originals to share / archive.

Do not use this skill when:

  • The user wants the same size as the originals — that's a no-op.
  • The user is upscaling — use fast-resize (or upscale-image for AI upscale).
  • The user wants to keep original quality — this skill assumes lossy thumbnail-grade output.

Inputs

  1. Input directory — required.
  2. Size — pixel size. Single number is shorthand for NxN (fit within square). Default: 512.
  3. Output dir — default: <input>/thumbnails/. The skill never overwrites originals.
  4. Format — output format. Default: jpg (best size/quality balance for thumbs). Options: jpg, png, webp, avif.
  5. Quality — JPEG/WebP/AVIF quality. Default: 80.
  6. Recursive--recursive to descend. Mirrors subdirectory structure under the output dir.
  7. Naming — default: same base name. --prefix <s> or --suffix <s> if collision is a risk.

Procedure

  1. Verify vipsthumbnail is on PATH. If missing, point at install-deps. No graceful fallback — if vips isn't installed, the skill's whole reason to exist is gone; tell the user to install or use batch-resize.

  2. Enumerate input files (image extensions only).

  3. For each file:

    vipsthumbnail "<input>" \
      --size "<size>" \
      --output "<output-dir>/<basename>.<ext>[Q=<quality>]"
    

    For non-JPEG outputs, the [Q=N] syntax still works for WebP/AVIF.

  4. For very large batches, parallelise with find ... | xargs -P <ncpu> -I{} vipsthumbnail .... vips is internally threaded but per-image work is small enough that process-level parallelism wins on >5k batches.

Read the full file on GitHub · 63 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 63 lines · 56 tokens per session scan A 0184962918d0

Subscribe to this mod's changes

fast-thumbnail is a skill published in the GitHub repository danielrosehill/Claude-Image-Production-Plugin (16 stars, last pushed 22d ago), licensed MIT. It adds 56 tokens to every session and 850 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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