For quick start install Nuget Package RestImageResize (or RestImageResize.EPiServer for EpiServer CMS based site) with nuget Package Manager Console and add image url with query like in following example:

<img src="~/Content/Images/bigcat.JPG?width=1200&height=260&transform=fill" />

Query syntax:

Parameters "width" and "height" - numbers from 0 to 2147483647, if any of them is missed value will be automatically ajusted according to transformation type, for 'fit' transformations missed dimension is ignored for other is treat as unchangeable.

Parameter "transform" can be specified with one of the following values: "fit", "fill", "downFit", "downFill", "crop", "stretch". If parameter is missed - "downFit" value will be used as default. You can configure this behaviour with "RestImageResize.DefautTransform" appSettings configuration section's item.

After installing RestImageResize.EPiServer package, add next code to your initialization module.

For EPiServer 7.5/8/9+:

OpenWaves.ServiceLocator.SetResolver(new OpenWaves.BasicResolver().RegisterRestImageResize());

For older versions:

OpenWaves.ServiceLocator.SetResolver(new OpenWaves.BasicResolver().RegisterWebImageTransformationModule());

Image transformation queries can be protected from DOS attacs from a third-party by hashing a query with a private key.

By default all valid private keys should be added to RestImageResize.PrivateKeys app setting in format {pk1:abc123|pk2:456edf} (keys are pipe-delimited, each containing a name and a private key itself). It is also possible to use another storage (eg EPiServer) for private keys: implement your own IPrivateKeyProvider and register it in OpenWaves service resolver:

public class HardcodedPrivateKeyProvider : IPrivateKeyProvider
{
    public IEnumerable<PrivateKey> GetAllPrivateKeys()
    {
        return new[]
        {
            new PrivateKey
            {
                Name = "MySecretKey",
                Key = "123456789abcdef"
            }
        };
    }
}

// In app configuration code:
OpenWaves.ServiceLocator.SetResolver(new OpenWaves.BasicResolver()
    .RegisterRestImageResize()
    .Register<IPrivateKeyProvider>(new HardcodedPrivateKeyProvider())
);

When at least one private key is configured, all image transformation requests should contain additional h query string parameter with SHA1 hash of the query in format (strings are lowercased):

private-key:width:height:transform

For example, for the URL http://myserver.com/images/logo.png?width=200&height=100&transform=DownFit and a private key 123456789ABCDEF, SHA1 hash of the query string 123456789abcdef:200:100:downfit, which is 2649a43c840fb3398e61672b988917e9c4109cd3 should be added in h parameter. So the resulting URL would be: http://myserver.com/images/logo.png?width=200&height=100&transform=downfit&h=2649a43c840fb3398e61672b988917e9c4109cd3.

If provided hash is wrong, then transformation parameters were changed or private key is not valid. In this case 403 Forbidden error will be returned from the server.

C# clients could use RestImageResize.Security.Sha1HashGenerator from RestImageResize assembly to generate hashes for image queries:

var hashGenerator = new RestImageResize.Security.Sha1HashGenerator();
var hash = hashGenerator.ComputeHash("123456789ABCDEF", 200, 100, ImageTransform.DownFit);

The feature added in v1.1.5 allows to configure log file for RestImageResize by adding the following configuration section:

  <configSections>
    <section name="restImageResize.logging" type="RestImageResize.Utils.LoggingConfigurationSection, RestImageResize" />
  </configSections>
  
  <restImageResize.logging 
    logSeverityThreshold="Debug" 
    logServiceType="OpenWaves.FileLoggingService, OpenWaves"
    logDirectory="~/App_Data/logs/" />

Default configuration is:

  <restImageResize.logging logSeverityThreshold="Info"  logServiceType="RestImageResize.Utils.DebugOutputLoggingService, RestImageResize"/>