gistfile1.cs

var resizedImage = origImage.ToSize(260);

var jpegEncoder = GetEncoder(ImageFormat.Jpeg);
var qualityEncoder = Encoder.Quality;
var qualityParam = new EncoderParameter(qualityEncoder, 100L);
var parameters = new EncoderParameters(1);
parameters.Param[0] = qualityParam;

// Cambiamos la calidad del jpeg
context.Response.ContentType = "image/jpeg";
resizedImage.Save(context.Response.OutputStream, jpegEncoder, parameters);