image-compare

image-compare is a skill for Claude Code, Codex from teimurjan/blazediff. It costs 49 tokens per session (2,376 once invoked), scanned A, original, MIT.

A command-line tool that compares two image files and reports their differences by region. It can help determine whether two screenshots, exports, or rendered images are identical or visually changed.

In plain words
What is it for?
Comparing PNGs and other image files, finding changed regions, checking for identical pixels, and measuring perceptual similarity.
Why use it?
It shows where an image changed without requiring you to inspect two full images side by side. This helps detect accidental visual changes in generated output.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Comparing PNGs and other image files, finding changed regions, checking for identical pixels, and measuring perceptual similarity.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/teimurjan/blazediff/image-compare
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 teimurjan/blazediff --skill image-compare
Clone the repo
git clone --depth 1 https://github.com/teimurjan/blazediff

Made for: Claude Code, Codex.

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 image-compare

README.md
[![agentmods](https://agentmods.dev/badge/skills/teimurjan/blazediff/image-compare/github.svg)](https://agentmods.dev/skills/teimurjan/blazediff/image-compare)
Your own site
<a href="https://agentmods.dev/skills/teimurjan/blazediff/image-compare"><img src="https://agentmods.dev/badge/skills/teimurjan/blazediff/image-compare/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 image-compare

Your own site · 80×15
<a href="https://agentmods.dev/skills/teimurjan/blazediff/image-compare"><img src="https://agentmods.dev/badge/skills/teimurjan/blazediff/image-compare.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,376 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 $0.00049 $0.02376
Opus 5.5 $0.00020 $0.00950
Sonnet 5.5 $0.00010 $0.00475
Haiku 4.5 $0.00005 $0.00238

Measured 1mo ago against content hash 63a604644508, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

image-compare 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 1mo 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.

skill/image-compare/SKILL.md · 184 lines

How it starts

The opening of the file, as written. The whole thing — 184 lines — stays where its author put it; the contents beside it link to each section on GitHub.

image-compare

Two image files in, a verdict out. No baselines, no manifest, no browser.

CLI binary is blazediff-cli (npm i -g @blazediff/cli).

Not this skill: capturing a running app, managing baselines, or re-running a visual regression suite → use the blazediff skill instead (it owns .blazediff/, blazediff-agent, and the check/rewrite loop). If the working directory has a .blazediff/manifest.json and the user is asking about routes rather than files, you are in the wrong skill.

Be terse

  • Pass --json on every call; parse fields. Do not echo CLI output.
  • Never send whole images to a model when interpret has located the regions — see Send crops, not pages below. This is the point of the skill.
  • One final summary line: N regions | <severity> | <one-clause verdict>.

Pick the command by the question

The user is asking Command Read from it
"what changed?" / "describe the differences" interpret regions[] — bbox, changeType, position
"are these identical?" core-native different pixels (0 = byte-identical after decode)
"how different, perceptually?" ssim SSIM score, 1.0 = identical
"did quality degrade?" (compression, resize, generative output) msssim multi-scale score, 1.0 = identical
"where are the structural differences?" gmsd -o map.png deviation, 0.0 = identical

interpret is the default. The others answer how much; only interpret answers what.

blazediff-cli interpret a.png b.png --json

Exit codes: 0 no regions, 1 regions found, 2 error. Safe to branch on.

Picking --source

  • pixel (default) — pixel-aligned renders: screenshots, PNG exports, chart renders, PDF rasterizations. Anything produced twice by the same renderer.
  • ms-ssim / ssim — images with resampling or compression noise: JPEGs, camera captures, generative-model output, anything that went through a lossy round-trip. Per-pixel deltas are everywhere in these, so pixel returns one giant region; the metric sources threshold a similarity map instead. Their boxes are coarser (map-grid resolution), but the pixel counts inside them are still exact.

Read the full file on GitHub · 184 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. 1mo ago First seen · 184 lines · 49 tokens per session scan A 63a604644508

Subscribe to this mod's changes

image-compare is a skill published in the GitHub repository teimurjan/blazediff (352 stars, last pushed today), licensed MIT. It adds 49 tokens to every session and 2,376 once invoked, about $0.0002 per session on Opus 5.5. 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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