Fairly sure there is no data stored other than the location of the image if you use an upload field because it does not know what you are uploading (pdf, image, word doc, etc.).

Using a media picker in Umbraco 7 you can still upload the file on the fly (just like an upload field) but have a lot more scope to work with the image dimensions once the image is added. You can also tailor that specific media picker with any constraints if required (e.g. only allow one item selected/uploaded from one specific section).

Other than the images not being re-used what are your other reasons for not using the media section for media items?

I find that using System.Drawing.Image is better:

public static int CreateMedia(Stream stream, string name, MediaTypes mediaType, int? parentId = -1)
        {
            MediaService mediaService = (MediaService)ApplicationContext.Current.Services.MediaService;
            var media = mediaService.CreateMedia(name, parentId.Value, mediaType.MediaTypeName());

            var folderData = GetLatestMediaFolder(name);

            using (var fileStream = File.Create(folderData.FileFullPath))
            {
                stream.Seek(0, SeekOrigin.Begin);
                stream.CopyTo(fileStream);
            }

            System.Drawing.Image img = System.Drawing.Image.FromFile(folderData.FileFullPath);

            media.SetValue("umbracoFile", folderData.Url);
            media.SetValue("umbracoWidth", img.Width);
            media.SetValue("umbracoHeight", img.Height);
            media.SetValue("umbracoBytes", new FileInfo(folderData.FileFullPath).Length);
            media.SetValue("umbracoExtension", Path.GetExtension(folderData.FileFullPath).Substring(1));
            mediaService.Save(media);

            return media.Id;
        }

    private static FolderData GetLatestMediaFolder(string fileName)
    {
        var root = System.Web.Hosting.HostingEnvironment.MapPath("~/");
        var mediaFolder = Path.Combine(root, "Media");
        var directories = Directory.GetDirectories(mediaFolder);
        int max = 0;
        int folderNumber = 1000;
        var latestDir = string.Empty;

        foreach (var dir in directories)
        {
            var d = new DirectoryInfo(dir).Name;

            if (int.TryParse(d, out int number))
            {
                folderNumber = number;
                if (folderNumber > max)
                {
                    max = folderNumber;
                }
            }
        }
        latestDir = (folderNumber + 1).ToString();

        var folderData = new FolderData()
        {
            FileFullPath = Path.Combine(mediaFolder, latestDir, fileName),
            DirectoryFullPath = Path.Combine(mediaFolder, latestDir),
            Url = $"/Media/{latestDir}/{fileName}"
        };

        Directory.CreateDirectory(folderData.DirectoryFullPath);
        return folderData;
    }

internal class FolderData
    {
        public string FileFullPath { get; set; }
        public string DirectoryFullPath { get; set; }
        public string Url { get; set; }
    }

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