ai-psd-thumbnails

Windows Explorer thumbnails & preview pane for Adobe Illustrator (.ai), Photoshop (.psd/.psb), EPS and SVG files — without installing any Adobe software.

A lightweight COM shell extension written in Rust, shipped as a per-machine x64 MSI.

Why

Explorer shows blank icons for design files unless you install heavyweight suites or risky third-party tools (some of which hijack your file associations — looking at you, SageThumbs). This project renders real content thumbnails and previews while never touching your file associations: .ai stays owned by Illustrator, double-click behavior never changes, and uninstalling removes every trace.

Formats

Format	How the thumbnail is produced
.ai (modern, PDF-based)	First page rendered via bundled pdfium
.ai (legacy, EPS-based)	Embedded DOS-EPS TIFF → %AI_Thumbnail → XMP thumbnail → Ghostscript*
.psd / .psb	Embedded Photoshop thumbnail resource, falling back to the flattened composite
.eps	Embedded DOS-EPS TIFF preview → XMP thumbnail → Ghostscript*
.svg	Rendered with resvg (external references disabled)

* Files with no embedded preview at all are rendered through Ghostscript if it is installed — as an isolated, sandboxed (-dSAFER), timeout-guarded subprocess. Ghostscript is AGPL and is therefore never bundled; the optional -setup.exe bundle offers to download the official installer as a separate product.

Install

Grab from Releases:

• ai-psd-thumbnails-<ver>.msi — the shell extension only (pick this if you don't care about preview-less EPS files, or already have Ghostscript).
• ai-psd-thumbnails-setup-<ver>.exe — same MSI, plus offers to download & install official Ghostscript first when it's missing (needs internet during install).

After installing, thumbnails appear for newly viewed files. Files Explorer has already cached as "no thumbnail" need a cache clear (scripts/clear-thumb-cache.ps1 from an elevated PowerShell) or simply copy/rename them once.

What it never does

• Never changes the default program, ProgID, or OpenWith entry of any extension — everything registers under association-neutral HKCR\SystemFileAssociations.
• Never loads Ghostscript in-process and never bundles it.
• Uninstall removes only its own registry keys and files.
• Bonus: the installer detects a known SageThumbs leftover that hijacks .ai and restores Adobe.Illustrator.28.

Build from source

Requires Rust (MSVC toolchain), and WiX 4.0.6 for the installer.

cargo build --workspace --release           # → target/release/thumb_viewer.dll
cargo test --workspace --exclude installer-ca
installer/build-msi.ps1                     # → installer/ai-psd-thumbnails-<ver>.msi
installer/build-bundle.ps1                  # → installer/ai-psd-thumbnails-setup-<ver>.exe

Dev registration without the MSI: elevated scripts/dev-register.ps1 / dev-unregister.ps1. See CLAUDE.md for the full operational reference (architecture, pdfium pin, registry contract, dev-loop gotchas).

License

MIT. Bundled pdfium.dll is BSD/Apache-licensed (licenses). Ghostscript is AGPL and is not part of this software — it is only ever an optional, separately installed product.