This fork is intended for current versions of .NET. Includes the latest version of the library libwebp.dll v1.6.0. The structures have been updated to match the current version of the library.

The wrapper work only 64-bit Windows system.

Package	Download
Webp-Wrapper-for-NET-Win-x64

dotnet add package Webp-Wrapper-for-NET-Win-x64

WebP-wrapper

Wrapper for libwebp in C#. The most complete wrapper in pure managed C#.

Exposes Simple Decoding and Encoding API, Advanced Decoding and Encoding API (with statistics of compression), Get version library and WebPGetFeatures (info of any WebP file). Exposed get PSNR, SSIM or LSIM distortion metrics.

The wrapper is in safe managed code in one class. No need for external dll except libwebp_x64.dll (included). The wrapper work only 64-bit Windows system.

The code is commented and includes simple examples for using the wrapper.

Decompress Functions:

Load WebP image for WebP file

using (WebP webp = new WebP())
  Bitmap bmp = webp.Load("test.webp");

Decode WebP filename to bitmap and load in PictureBox container

byte[] rawWebP = File.ReadAllBytes("test.webp");
using (WebP webp = new WebP())
  this.pictureBox.Image = webp.Decode(rawWebP);

Advanced decode WebP filename to bitmap and load in PictureBox container

byte[] rawWebP = File.ReadAllBytes("test.webp");
WebPDecoderOptions decoderOptions = new WebPDecoderOptions();
decoderOptions.use_threads = 1;     //Use multhreading
decoderOptions.flip = 1;   			//Flip the image
using (WebP webp = new WebP())
  this.pictureBox.Image = webp.Decode(rawWebP, decoderOptions);

Get thumbnail with 200x150 pixels in fast/low quality mode

using (WebP webp = new WebP())
	this.pictureBox.Image = webp.GetThumbnailFast(rawWebP, 200, 150);

Get thumbnail with 200x150 pixels in slow/high quality mode

using (WebP webp = new WebP())
	this.pictureBox.Image = webp.GetThumbnailQuality(rawWebP, 200, 150);

Compress Functions:

Save bitmap to WebP file

Bitmap bmp = new Bitmap("test.jpg");
using (WebP webp = new WebP())
  webp.Save(bmp, 80, "test.webp");

Encode to memory buffer in lossy mode with quality 75 and save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeLossy(bmp, 75);
File.WriteAllBytes("test.webp", rawWebP); 

Encode to memory buffer in lossy mode with quality 75 and speed 9. Save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeLossy(bmp, 75, 9);
File.WriteAllBytes("test.webp", rawWebP); 

Encode to memory buffer in lossy mode with quality 75, speed 9 and get information. Save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeLossy(bmp, 75, 9, true);
File.WriteAllBytes("test.webp", rawWebP); 

Encode to memory buffer in lossless mode and save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeLossless(bmp);
File.WriteAllBytes("test.webp", rawWebP); 

Encode to memory buffer in lossless mode with speed 9 and save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeLossless(bmp, 9);
File.WriteAllBytes("test.webp", rawWebP); 

Encode to memory buffer in near lossless mode with quality 40 and speed 9 and save to file

byte[] rawWebP = File.ReadAllBytes("test.jpg");
using (WebP webp = new WebP())
  rawWebP = webp.EncodeNearLossless(bmp, 40, 9);
File.WriteAllBytes("test.webp", rawWebP); 

Another Functions:

Get version of libwebp.dll

using (WebP webp = new WebP())
  string version = "libwebp.dll v" + webp.GetVersion();

Get info from WebP file

byte[] rawWebp = File.ReadAllBytes(pathFileName);
using (WebP webp = new WebP())
  webp.GetInfo(rawWebp, out width, out height, out has_alpha, out has_animation, out format);
MessageBox.Show("Width: " + width + "\n" +
                "Height: " + height + "\n" +
                "Has alpha: " + has_alpha + "\n" +
                "Is animation: " + has_animation + "\n" +
                "Format: " + format);

Get PSNR, SSIM or LSIM distortion metric between two pictures

int metric = 0;  //0 = PSNR, 1= SSIM, 2=LSIM
Bitmap bmp1 = Bitmap.FromFile("image1.png");
Bitmap bmp2 = Bitmap.FromFile("image2.png");
using (WebP webp = new WebP())
	result = webp.GetPictureDistortion(source, reference, metric);
	                    MessageBox.Show("Red: " + result[0] + "dB.\nGreen: " + result[1] + "dB.\nBlue: " + result[2] + "dB.\nAlpha: " + result[3] + "dB.\nAll: " + result[4] + "dB.", "PSNR");

MessageBox.Show("Red: " + result[0] + dB\n" +
                "Green: " + result[1] + "dB\n" +
                "Blue: " + result[2] + "dB\n" +
                "Alpha: " + result[3] + "dB\n" +
                "All: " + result[4] + "dB\n");

Thanks to jzern@google.com

Without their help this wrapper would not have been possible.