LMSupply.Captioner

LMSupply.Captioner

Local image captioning for .NET with automatic model downloading.

Features

• Zero-config: Models download automatically from HuggingFace
• GPU Acceleration: CUDA, CoreML (macOS)
• Cross-platform: Windows, Linux, macOS
• Simple API: Just 2 lines of code to get started

Quick Start

using LMSupply.Captioner;

// Load the default captioning model
var captioner = await LocalCaptioner.LoadAsync("default");

// Generate a caption
var result = await captioner.CaptionAsync("photo.jpg");
Console.WriteLine(result.Caption);
// Output: "A cat sitting on a windowsill looking outside"

Available Models

quality is published in quantized variants; a load takes the one the hardware tier picks, or the one you name with QuantizationHint or a qualifier ("quality:fp16"). LocalCaptioner.GetDownloadSizeBytesAsync answers what a load will download, for a consent screen.

using LMSupply.Captioner;

long bytes = await LocalCaptioner.GetDownloadSizeBytesAsync("quality");

await using var captioner = await LocalCaptioner.LoadAsync("quality",
    new CaptionerOptions { Detail = CaptionDetail.Detailed, MaxLength = 100 });
var result = await captioner.CaptionAsync("photo.jpg");

Detail (Brief · Detailed · Paragraph) is read by quality; default captions at one level and refuses any other value at load. Prompt (caption prefix) is read by default; quality refuses it — its prompt selects the task.

Advanced Usage

using LMSupply;   // ExecutionProvider

// Custom options
var options = new CaptionerOptions
{
    MaxLength = 50,
    Provider = ExecutionProvider.Cuda
};

var captioner = await LocalCaptioner.LoadAsync("default", options);
var result = await captioner.CaptionAsync("image.jpg");

Console.WriteLine($"Caption: {result.Caption}");
Console.WriteLine($"Confidence: {result.Confidence:P1}");

GPU Acceleration

Install the appropriate GPU package for your hardware:

# NVIDIA GPU
dotnet add package Microsoft.ML.OnnxRuntime.Gpu

AMD / Intel GPUs on Windows have no ONNX provider on ONNX Runtime 1.25+ (DirectML was removed in 0.67.0); captioning runs on CPU there.