ExplorerLens.io — GPU-Accelerated Thumbnail Generator

High-performance Windows Shell extension for 200+ file formats

ExplorerLens.io generates thumbnails for images, videos, documents, 3D models, fonts, archives, and more using DirectX 11/12 GPU acceleration and multi-threaded processing. The project root directory is ExplorerLens.io, and this repository is the production codebase for the Explorer extension, engine, and manager UI.

Type	Windows Shell Extension (IThumbnailProvider COM in-process DLL)
GPU	DirectX 11 device + compute shaders · GPU resize · HDR tone-map · CPU GDI+ fallback
Platform	Windows 10 1809+ / Windows 11 (x64) · macOS/Linux: planned Phase 5
Formats	200+ extensions — HEIC, AVIF, JXL, WebP, RAW, PDF, CBZ, CBR, EPUB, glTF, DDS, EXR, MP4, MP3, TTF …
Cameras	100+ RAW formats — Canon (CR2/CR3), Nikon (NEF), Sony (ARW), Fujifilm, Adobe DNG, Olympus, Hasselblad …
Language	C++20 · MSVC v145 · Visual Studio 18 2026 BuildTools
Build	CMake 4.3 · Ninja · vcpkg / local external libs
Tests	4,744 unit tests · 5 benchmarks · 100% pass rate
Install	One-click MSI or winget install ExplorerLens.ExplorerLens or regsvr32 LENSShell.dll

🏷️ GitHub Topics (live on this repo)

windows-shell-extension   thumbnail-provider   ithumbnailprovider   windows-explorer-extension   file-preview   gpu-acceleration   directx   cpp20   heic   avif   jpeg-xl   raw-image   webp   windows-11   comic-book   image-decoder   thumbnail-cache   com-server   pdf-viewer   msvc

More keyword tags for discoverability: ithumbnailprovider · iextractimage · com-dll · directx11 · directx12 · vulkan-compute · hlsl · libraw · libheif · libjxl · libavif · mupdf · libwebp · dav1d · cbz-reader · cbr-reader · manga-viewer · epub-reader · archive-viewer · 3d-model-viewer · gltf · stl-viewer · dicom · openexr · hdr · font-preview · video-thumbnail · audio-waveform · wic · simd · avx2 · zero-copy · lru-cache · windows-registry · regsvr32 · shell-handler

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📚 Documentation

Getting Started:

• Quick Start Guide — Developer onboarding: clone → build → register → test
• Build Quick Reference — Complete build instructions
• Installation Guide — Installation and setup
• Testing Guide — Validation and test procedures

Project Organization:

• Project Structure — Complete directory organization
• System Overview — Architecture diagrams + cache layers
• Documentation Index — Complete documentation index

Development:

• Development Guide — Developer documentation
• Contributing — How to contribute
• Coding Standards — Code style and conventions
• Build Scripts — Build automation reference

Server & Ops:

• LensServer — Lightweight REST thumbnail server (port 8765)
• Dockerfile — Windows Container 2-stage build image

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✨ Features

Supported Formats (200+ file extensions via 25 specialized decoders)

Core Image Formats (✅ Fully Supported)

• Standard: .jpg, .jpeg, .png, .bmp, .gif, .tiff, .tif
• Modern: .webp (WebP), .avif (AV1 Image), .jxl (JPEG XL) ✅
• Mobile: .heif, .heic, .hif, .avci, .avcs (Apple HEIC/HEIF) ✅
• Implementation: JXL via libjxl 0.11.1 | HEIF via libheif 1.19.5 (with WIC fallback on Windows 11)

Archives & Comic Books (✅ Fully Supported)

• Comic Books: .cbz, .cbr, .cb7, .cbt
• E-Books: .epub, .mobi, .azw, .azw3, .fb2
• Archives: .zip, .rar, .7z, .tar, .gz, .bz2, .xz

Professional Formats (✅ RAW Photos & Modern Formats)

• RAW Photos: .cr2, .cr3, .nef, .arw, .orf, .dng, .rw2, .raf, .pef, .dcr, .mrw, .x3f and 100+ more camera formats (✅ LibRaw 0.21.3)
  • Features: Embedded JPEG thumbnail extraction (< 10ms), full RAW decode with demosaicing, EXIF orientation support, auto white balance
  • Cameras: Canon, Nikon, Sony, Olympus, Panasonic, Fujifilm, Pentax, Adobe DNG, Leica, Samsung, Hasselblad, Phase One, Sigma
• Modern Images: .jxl (JPEG XL) via libjxl 0.11.1, .heif/.heic (HEIF/HEIC) via libheif 1.19.5 + WIC fallback
  • JXL Features: Next-gen format support, better compression than WebP, wide color gamut
  • HEIF Features: Apple iPhone photos (iOS 11+), HDR support, 16-bit depth, wide color
• Design: .psd, .psb (Photoshop), .svg (vector graphics)
• HDR: .exr (OpenEXR), .hdr (Radiance RGBE)
• Texture: .dds (DirectX textures)
• Legacy: .tga (Targa), .ico (icons), .jp2 (JPEG2000)

Video & Audio (✅ Media Foundation)

• Video: .mp4, .mkv, .avi, .webm, .mov, .wmv, .flv, .mpg, .mpeg, .ts, .mts, .m2ts, .3gp, .vob, .ogv (22 extensions)
• Audio: .mp3, .flac, .m4a, .ogg, .wma, .wav, .opus - extracts album art or generates waveform

Documents & Fonts (✅ Shell API + GDI+)

• Documents: .pdf, .docx, .xlsx, .pptx, .epub (Office/Edge required for Office formats)
• Fonts: .ttf, .otf, .ttc - renders font preview

3D Models (✅ Built-in parser)

• Models: .obj, .stl, .gltf, .glb - orthographic preview rendering

Vector Graphics (✅ GDI+ renderer)

• SVG: .svg, .svgz - rasterizes vector graphics to thumbnail

Special Formats (✅ Native decoders)

• QOI: .qoi (Quite OK Image - fastest decode format)
• ICO: .ico, .cur (Windows icons/cursors)
• TGA: .tga (Targa)
• PPM: .ppm, .pgm, .pbm, .pnm, .pam, .pfm (Netpbm formats)
• DDS: .dds (DirectX textures)
• HDR: .hdr, .pic (Radiance RGBE)

Legend: ✅ = Production ready | ⚠️ = Requires external dependency | 📋 = Planned

Performance

• ⚡ GPU Accelerated - DirectX 11 hardware rendering
• 🚀 Smart Caching - Instant display of cached thumbnails
• 📦 Multi-Format - Single extension for all formats
• 🎯 Low Memory - Efficient resource usage

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🚀 Quick Start

Requirements

• Windows 10 1809+ or Windows 11 (64-bit)
• Visual Studio 18 2026 BuildTools (MSVC v145 toolset)
• Administrator privileges for installation

Build

REM Open "x64 Native Tools Command Prompt for VS 2026"
cd ExplorerLens
RUN-BUILD.bat

See Build Quick Reference for detailed instructions.

Install

REM Register DLL (as Administrator)
cd x64\Release
regsvr32 LENSShell.dll

Configure

Run LENSManager.exe to enable/disable file format categories.

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🏗️ Architecture

System Components

Thumbnail Generation Data Flow

Build Pipeline

GPU Render Priority: D3D11 → D3D12 → Vulkan Compute → GDI+ (software)

COM interfaces implemented: IThumbnailProvider, IInitializeWithStream, IPropertyStore, IPropertyStoreCapabilities, IExtractImage2, IPersistFile, IQueryInfo

CLSID: {9E6ECB90-5A61-42BD-B851-D3297D9C7F39}

Project Directory Layout

graph TD
    ROOT["📁 <b>ExplorerLens.io</b>"]

    ROOT --> SHELL["🔌 <b>LENSShell/</b><br/>COM Shell Extension DLL"]
    ROOT --> MGR["🖥️ <b>LENSManager/</b><br/>WTL Admin GUI"]
    ROOT --> ENG["⚙️ <b>Engine/</b><br/>Core Decode + Render Library"]
    ROOT --> BS["🔨 <b>build-scripts/</b><br/>PowerShell Build Automation"]
    ROOT --> EXT["📦 <b>external/</b><br/>Statically Linked Libraries"]
    ROOT --> DOCS["📚 <b>docs/</b><br/>Architecture &amp; Guides"]
    ROOT --> SDK["🧩 <b>SDK/</b><br/>Plugin SDK · C ABI"]
    ROOT --> PKG["📋 <b>packaging/</b><br/>MSI · MSIX · Inno Setup"]
    ROOT --> SLN["📄 <b>LENSShell.sln</b><br/>Visual Studio 18 2026 Solution"]

    ENG --> CORE["🏗️ <b>Core/</b><br/>Pipeline · Detection · SIMD"]
    ENG --> DEC["🖼️ <b>Decoders/</b><br/>25+ Format Decoders"]
    ENG --> GPU["⚡ <b>GPU/</b><br/>D3D11 · D3D12 · Vulkan"]
    ENG --> CACHE["💾 <b>Cache/</b><br/>Multi-tier Caching"]
    ENG --> MEM["🧠 <b>Memory/</b><br/>BitmapPool · Pressure Ctrl"]
    ENG --> PLUGIN["🔩 <b>Plugin/</b><br/>Plugin Ecosystem · Sandbox"]
    ENG --> AI["🤖 <b>AI/</b><br/>Smart Crop · IQA · Scene"]
    ENG --> TESTS["✅ <b>Tests/</b><br/>4,483 Unit Tests · 5 Benchmarks"]

    style ROOT fill:#1e3a5f,color:#fff,stroke:#4a9eff,stroke-width:2px
    style ENG  fill:#1b4332,color:#fff,stroke:#40916c,stroke-width:2px
    style SHELL fill:#2d2d2d,color:#fff,stroke:#888
    style MGR   fill:#2d2d2d,color:#fff,stroke:#888
    style BS    fill:#2d2d2d,color:#fff,stroke:#888
    style EXT   fill:#2d2d2d,color:#fff,stroke:#888
    style DOCS  fill:#2d2d2d,color:#fff,stroke:#888
    style SDK   fill:#2d2d2d,color:#fff,stroke:#888
    style PKG   fill:#2d2d2d,color:#fff,stroke:#888
    style SLN   fill:#2d2d2d,color:#fff,stroke:#888
    style CORE   fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style DEC    fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style GPU    fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style CACHE  fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style MEM    fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style PLUGIN fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style AI     fill:#1a3d2b,color:#d8f3dc,stroke:#52b788
    style TESTS  fill:#1a3d2b,color:#d8f3dc,stroke:#52b788

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🤝 Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

How to Help

• 🐛 Report bugs and issues
• 💡 Suggest features
• 🔧 Submit pull requests
• 📝 Improve documentation
• 🧪 Write tests

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📊 Status

Current Version: 32.3.0 "Fomalhaut-T" Build Status: 0 errors / 0 warnings Test Status: 4,483 unit tests, 5 benchmarks (100% pass rate) Codename: Fomalhaut-T — Annotation, HDR Tone Mapping & Format Detection

See CHANGELOG.md for the complete development history.

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🔧 Troubleshooting

Thumbnails Not Appearing

REM Restart Windows Explorer
taskkill /f /im explorer.exe && start explorer.exe

REM Clear Windows thumbnail cache
del /f /s /q "%LocalAppData%\Microsoft\Windows\Explorer\thumbcache_*.db"

Check DLL Registration

reg query "HKCR\CLSID\{9E6ECB90-5A61-42BD-B851-D3297D9C7F39}\InprocServer32"

See Troubleshooting Guide for more troubleshooting.

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📦 External Libraries

Compression: zlib 1.3.1, LZ4 1.10.0, zstd 1.5.7, LZMA 26.00, minizip-ng 4.0.10 Images: libwebp 1.5.0, libavif 1.3.0 (dav1d 1.5.1), libjxl 0.11.1, LibRaw 0.21.3 Archives: UnRAR 7.2.1, minizip-ng 4.0.10 Video: Windows Media Foundation (system API) Rendering: DirectX 11, GDI+

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📄 License

MIT License - See LICENSE for details.

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🔗 Links

• Repository: Internal project repository
• Issues: Use project issue tracker configured for this workspace
• Discussions: Use team discussion channel

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Built with ❤️ using C++20, DirectX 11/12, and Vulkan — Windows Shell Extension for 200+ formats

Last Updated: March 29, 2026 (v25.0.0 "Rigel")