I wrote this when I needed to make all of my images folders purely anonymous reading. I dont want to ever run into an issue of an image that is not checked in. Create a console app and replace the main with the code below. It will crawl the whole site and make all images (publishing images) fully anonymous for reading.

 static void Main(string[] args)
        {
            bool requireApproval = false;

            // open the site
            SPSite site = new SPSite(http://YOUR_SITE);
            // open the web
            SPWeb web = site.OpenWeb();

            ProcessWeb(web, requireApproval);

            return;

            // open the web collection
            SPWebCollection webcoll = web.Webs;

            // parse through the webs
            foreach (SPWeb webx in webcoll)
            {
                ProcessWeb(webx, requireApproval);
            }

            Console.Read();
        }

        public static void ProcessWeb(SPWeb webx, bool requireApproval)
        {
            Console.Write("Processing " + webx.Url + "\n");

            // get the list
            SPListCollection lists = webx.Lists;

            // looks for our Pages list
            foreach (SPList siteList in lists)
            {
                if (siteList.Title == "Images")
                {

                    //PublishingWeb pweb = PublishingWeb.GetPublishingWeb(webx);

                    //PublishingPageCollection ppages = pweb.GetPublishingPages();

                    bool fixSite = false;

                    siteList.EnableModeration = false;
                    siteList.ForceCheckout = false;
                    siteList.AllowEveryoneViewItems = false;
                    siteList.DraftVersionVisibility = DraftVisibilityType.Reader;
                    siteList.Update();

                    fixSite = true;

                    if (siteList.WorkflowAssociations.Count > 1)
                    {
                        SPWorkflowAssociationCollection wfCol = siteList.WorkflowAssociations;
                        SPWorkflowAssociation wf = wfCol.GetAssociationByName("Parallel Approval", System.Globalization.CultureInfo.CurrentCulture);

                        wf.Enabled = false;

                        siteList.UpdateWorkflowAssociation(wf);
                    }
                }
            }

            if (webx.Webs.Count > 0)
            {
                foreach (SPWeb webNext in webx.Webs)
                {
                    ProcessWeb(webNext, requireApproval);

                }
            }
        }