Hi Barry,

Yeah, I have... In PNG's anyway.

It'll only happen to a JPG if your original image is of lower quality than the output which defaults to 90%. You can change that output adding the &quality= querystring parameter to your request url reduce output size.

The PNG output size increase is due to .NET not optimizing the output palette as well as they could. To fix this you have two options:

• Install the ImageProcessor.PostProcessor package via Nuget. This will run embedded tools on the cached image to further reduce the file size.
  The initial cached image is returned unoptimized to reduce time to first byte but subsequent visits to the site will yield an optimized image.
• Change the format to an indexed png by adding the querystring parameter &format=png8 to your request url.
  This will run the image through a highly optimized quantizer. For most images this will work, but if you have light grey to white gradients, banding will occur.

If you choose to augment the querystring you can actually automate the process by tapping into one of ImageProcessor.Web's processing events. Here's a full sample of how to do that in Umbraco.

namespace Your.Namespace
{
    using ImageProcessor.Web.HttpModules;

    using Umbraco.Core;

    /// <summary>
    /// Taps into ImageProcessor.Web events to intecept image requests to adjust output quality file size.
    /// </summary>
    public class ImageProcessorInterceptorEventHandler : IApplicationEventHandler
    {
        /// <summary>
        /// Boot-up is completed, this allows you to perform any other boot-up logic required for the application.
        /// Resolution is frozen so now they can be used to resolve instances.
        /// </summary>
        /// <param name="umbracoApplication">The current <see cref="UmbracoApplicationBase"/></param>
        /// <param name="applicationContext">The Umbraco <see cref="ApplicationContext"/> for the current application.</param>
        public void OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
            // Intercept ImageProcessor requests to alter output quality and file size.
            ImageProcessingModule.OnProcessQuerystring += (sender, args) =>
            {
                if ((args.RawUrl.Contains(".jpg") || args.RawUrl.Contains(".jpeg")) && !args.Querystring.Contains("quality="))
                {
                    // 75 is pretty good for web output. You might be able to push it down to 65.
                    return args.Querystring += "&quality=75";
                }

                if (args.RawUrl.Contains(".png") && !args.Querystring.Contains("format=png8"))
                {
                    return args.Querystring += "&format=png8";
                }

                return args.Querystring;
            };
        }

        /// <summary>
        /// ApplicationContext is created and other static objects that require initialization have been setup
        /// </summary>
        /// <param name="umbracoApplication">The current <see cref="UmbracoApplicationBase"/></param>
        /// <param name="applicationContext">The Umbraco <see cref="ApplicationContext"/> for the current application.</param>
        public void OnApplicationInitialized(
            UmbracoApplicationBase umbracoApplication,
            ApplicationContext applicationContext)
        {
        }

        /// <summary>
        /// All resolvers have been initialized but resolution is not frozen so they can be modified in this method
        /// </summary>
        /// <param name="umbracoApplication">The current <see cref="UmbracoApplicationBase"/></param>
        /// <param name="applicationContext">The Umbraco <see cref="ApplicationContext"/> for the current application.</param>
        public void OnApplicationStarting(
            UmbracoApplicationBase umbracoApplication,
            ApplicationContext applicationContext)
        {
        }
    }
}

Hope that helps. :)