Decoding

Decode to Bitmap

The SimpleDecoder class decodes WebP images into System.Drawing.Bitmap (32bpp ARGB):

using Imazen.WebP;

var decoder = new SimpleDecoder();

// From byte array
byte[] data = File.ReadAllBytes("image.webp");
using Bitmap bmp = decoder.DecodeFromBytes(data, data.LongLength);

// From stream
using var stream = File.OpenRead("image.webp");
using Bitmap bmp = decoder.DecodeFromStream(stream);

Decode to Raw Pixels (Cross-Platform)

The static WebPDecoder class decodes to raw pixel arrays without System.Drawing:

using Imazen.WebP;

byte[] data = File.ReadAllBytes("image.webp");

// Default: BGRA format
byte[] pixels = WebPDecoder.Decode(data, out int width, out int height);

// Specify format
byte[] rgba = WebPDecoder.Decode(data, out int w, out int h, WebPPixelFormat.Rgba);

Decode into Existing Buffer

Avoid allocations by decoding directly into a pre-allocated buffer:

byte[] data = File.ReadAllBytes("image.webp");

// Get dimensions first
WebPInfo.TryGetSize(data, out int width, out int height);

// Allocate and decode into buffer
int stride = width * 4;
byte[] output = new byte[stride * height];
WebPDecoder.Decode(data, output, stride, WebPPixelFormat.Bgra);

Decode from Stream

using var stream = File.OpenRead("image.webp");
byte[] pixels = WebPDecoder.DecodeFromStream(stream, out int width, out int height, WebPPixelFormat.Rgba);

Format Detection

Check if data is a valid WebP file without decoding:

// From byte array
bool isWebP = WebPDecoder.IsWebP(data);

// From seekable stream (position is restored)
using var stream = File.OpenRead("unknown.bin");
bool isWebP = WebPDecoder.IsWebP(stream);

Image Probing

Retrieve image metadata without full decoding using WebPInfo:

byte[] data = File.ReadAllBytes("image.webp");

// Quick size check
if (WebPInfo.TryGetSize(data, out int width, out int height))
    Console.WriteLine($"{width}x{height}");

// Full feature info
var info = WebPInfo.GetImageInfo(data);
Console.WriteLine($"Alpha: {info.HasAlpha}, Animated: {info.HasAnimation}, Format: {info.Format}");