How to get all large media items from Umbraco. You COULD use the Media Service, but this will be CONSIDERABLY faster. This example is just a surface controller and has no authentication. On a production environment you'd probably want to limit something like this to authenticated users.

GiantMediaController.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;
using System.Web.Mvc;
using Umbraco.Core.Models;
using Umbraco.Web;
using Umbraco.Web.Mvc;

namespace MySite.Web.Controllers
{
    public class GiantMediaController : SurfaceController
    {
        public ActionResult GetGiantImages()
        {
            var builder = new StringBuilder();

            var bigImageData = GetLargeImages();

            builder.AppendLine($"<h1>Images Over 3MB ({bigImageData.Count()} Files):</h1>");

            builder.AppendLine("<table border=\"1\">");

            builder.AppendLine("<tr><th>Image Name</th><th>Size (MB)</th><th>Width</th><th>Height</th><th>Link to File</th><th>In Recycle Bin</th></tr>");

            foreach (var image in bigImageData)
            {
                var umbracoImage = Umbraco.TypedMedia(image.Id);

                builder.AppendLine($"<tr><td>{image.Text}</td><td>{(image.DataNVarchar / 1048576).ToString("F2")} MB</td><td>{umbracoImage?.GetPropertyValue("umbracoWidth", "n/a")}</td><td>{umbracoImage?.GetPropertyValue("umbracoHeight", "n/a")}</td><td><a href='{umbracoImage?.Url}'>{umbracoImage?.Url}</a></td><td>@(umbracoImage == null)</td></tr>");
            }

            builder.AppendLine("</table>");

            return Content(builder.ToString());
        }
        private IEnumerable<BigImage> GetLargeImages()
        {
            //Do this as a SQL query, as listing and filtering media via the service API is VERY slow
            //Currently looking for images over 3MB, can make this smaller if need be
            var bigImageData = ApplicationContext.DatabaseContext.Database.Query<BigImage>(@"SELECT umbracoNode.id, umbracoNode.text, cmsPropertyData.dataNvarchar FROM cmsPropertyData 
                INNER JOIN umbracoNode ON cmsPropertyData.contentNodeId = umbracoNode.id
                INNER JOIN cmsPropertyType ON cmsPropertyData.propertytypeid = cmsPropertyType.id
                WHERE cmsPropertyType.Alias = 'umbracoBytes' AND dataNVarchar IS NOT NULL AND 
                (CASE WHEN ISNUMERIC(dataNvarchar) = 1 AND NOT dataNvarchar LIKE '%,%' AND NOT dataNvarchar LIKE '%.%' THEN CAST(dataNvarchar AS int) ELSE 0 END) > 3145728
                ORDER BY CAST(dataNvarchar AS int) DESC").ToList();

            return bigImageData;
        }
    }

    public class BigImage
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public decimal DataNVarchar { get; set; }
    }
}