Encoding

Simple Encoding (Bitmap)

The SimpleEncoder class encodes System.Drawing.Bitmap objects to WebP:

using Imazen.WebP;

var encoder = new SimpleEncoder();
using var bitmap = new Bitmap("input.png");
using var stream = File.Create("output.webp");

// Lossy at quality 80
encoder.Encode(bitmap, stream, 80);

Set quality to -1 for lossless encoding:

encoder.Encode(bitmap, stream, -1);

Raw Buffer Encoding (Cross-Platform)

The static WebPEncoder class works with raw pixel arrays — no System.Drawing required:

using Imazen.WebP;

// From RGBA pixel data
byte[] encoded = WebPEncoder.Encode(
    rgbaPixels, width, height, width * 4,
    WebPPixelFormat.Rgba, quality: 80);

// Write directly to a stream
using var stream = File.Create("output.webp");
WebPEncoder.Encode(rgbaPixels, width, height, width * 4,
    WebPPixelFormat.Rgba, 80, stream);

Supported pixel formats: Bgra, Rgba, Bgr, Rgb.

Advanced Encoding Config

For fine-grained control, use WebPEncoderConfig with its fluent API:

using Imazen.WebP;

var config = new WebPEncoderConfig()
    .SetQuality(85)
    .SetMethod(6)           // 0=fast, 6=best compression
    .SetSharpYuv()          // Better RGB→YUV conversion
    .SetSnsStrength(50)     // Spatial noise shaping
    .SetFilterStrength(20)  // Deblocking filter
    .SetAlphaQuality(90);   // Alpha channel quality

// With Bitmap
var encoder = new SimpleEncoder();
encoder.Encode(bitmap, stream, config);

// With raw pixels
byte[] encoded = WebPEncoder.Encode(
    pixels, width, height, stride,
    WebPPixelFormat.Bgra, config);

Lossless Encoding

var config = new WebPEncoderConfig()
    .SetLossless()
    .SetMethod(6);  // Best lossless compression

// Or use lossless presets (0=fastest, 9=smallest)
var config = new WebPEncoderConfig()
    .SetLosslessPreset(6);

Near-Lossless

Near-lossless mode pre-processes the image to improve compression while maintaining visual quality:

var config = new WebPEncoderConfig()
    .SetLossless()
    .SetNearLossless(60);  // 0=max preprocessing, 100=off

Preset-Based Configuration

Initialize from a built-in preset tuned for specific content types:

var config = new WebPEncoderConfig(WebPPreset.WEBP_PRESET_PHOTO, quality: 80);

Available presets: WEBP_PRESET_DEFAULT, WEBP_PRESET_PICTURE, WEBP_PRESET_PHOTO, WEBP_PRESET_DRAWING, WEBP_PRESET_ICON, WEBP_PRESET_TEXT.

Target File Size

Encode to a specific file size instead of a quality level:

var config = new WebPEncoderConfig()
    .SetTargetSize(50_000);  // Target ~50KB

Configuration Validation

Always validate before encoding if building configs dynamically:

if (!config.Validate())
    throw new Exception("Invalid encoder config");

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