Action Image MVC3 Razor

You can use Url.Content which works for all links as it translates the tilde ~ to the root uri.

<a href="@Url.Action("Edit", new { id=MyId })">
    <img src="@Url.Content("~/Content/Images/Image.bmp")", alt="Edit" />
</a>

Building on Lucas's answer above, this is an overload that takes a controller name as parameter, similar to ActionLink. Use this overload when your image links to an Action in a different controller.

// Extension method
public static MvcHtmlString ActionImage(this HtmlHelper html, string action, string controllerName, object routeValues, string imagePath, string alt)
{
    var url = new UrlHelper(html.ViewContext.RequestContext);

    // build the <img> tag
    var imgBuilder = new TagBuilder("img");
    imgBuilder.MergeAttribute("src", url.Content(imagePath));
    imgBuilder.MergeAttribute("alt", alt);
    string imgHtml = imgBuilder.ToString(TagRenderMode.SelfClosing);

    // build the <a> tag
    var anchorBuilder = new TagBuilder("a");

    anchorBuilder.MergeAttribute("href", url.Action(action, controllerName, routeValues));
    anchorBuilder.InnerHtml = imgHtml; // include the <img> tag inside
    string anchorHtml = anchorBuilder.ToString(TagRenderMode.Normal);

    return MvcHtmlString.Create(anchorHtml);
}

Well, you could use @Lucas solution, but there's also another way.

 @Html.ActionLink("Update", "Update", *Your object value*, new { @class = "imgLink"})

Now, add this class on a CSS file or in your page:

.imgLink
{
  background: url(YourImage.png) no-repeat;
}

With that class, any link will have your desired image.

This turned out to be a very useful thread.

For those who are allergic to curly braces, here is the VB.NET version of Lucas' and Crake's answers:

Public Module ActionImage
    <System.Runtime.CompilerServices.Extension()>
    Function ActionImage(html As HtmlHelper, Action As String, RouteValues As Object, ImagePath As String, AltText As String) As MvcHtmlString

        Dim url = New UrlHelper(html.ViewContext.RequestContext)

        Dim imgHtml As String
        'Build the <img> tag
        Dim imgBuilder = New TagBuilder("img")
        With imgBuilder
            .MergeAttribute("src", url.Content(ImagePath))
            .MergeAttribute("alt", AltText)
            imgHtml = .ToString(TagRenderMode.Normal)
        End With

        Dim aHtml As String
        'Build the <a> tag
        Dim aBuilder = New TagBuilder("a")
        With aBuilder
            .MergeAttribute("href", url.Action(Action, RouteValues))
            .InnerHtml = imgHtml 'Include the <img> tag inside
            aHtml = aBuilder.ToString(TagRenderMode.Normal)
        End With

        Return MvcHtmlString.Create(aHtml)

    End Function

    <Extension()>
    Function ActionImage(html As HtmlHelper, Action As String, Controller As String, RouteValues As Object, ImagePath As String, AltText As String) As MvcHtmlString

        Dim url = New UrlHelper(html.ViewContext.RequestContext)

        Dim imgHtml As String
        'Build the <img> tag
        Dim imgBuilder = New TagBuilder("img")
        With imgBuilder
            .MergeAttribute("src", url.Content(ImagePath))
            .MergeAttribute("alt", AltText)
            imgHtml = .ToString(TagRenderMode.Normal)
        End With

        Dim aHtml As String
        'Build the <a> tag
        Dim aBuilder = New TagBuilder("a")
        With aBuilder
            .MergeAttribute("href", url.Action(Action, Controller, RouteValues))
            .InnerHtml = imgHtml 'Include the <img> tag inside
            aHtml = aBuilder.ToString(TagRenderMode.Normal)
        End With

        Return MvcHtmlString.Create(aHtml)

    End Function

End Module

This extension method also works (to be placed in an public static class):

    public static MvcHtmlString ImageActionLink(this AjaxHelper helper, string imageUrl, string altText, string actionName, object routeValues, AjaxOptions ajaxOptions)
    {
        var builder = new TagBuilder("img");
        builder.MergeAttribute("src", imageUrl);
        builder.MergeAttribute("alt", altText);
        var link = helper.ActionLink("[replaceme]", actionName, routeValues, ajaxOptions);
        return new MvcHtmlString( link.ToHtmlString().Replace("[replaceme]", builder.ToString(TagRenderMode.SelfClosing)) );
    }

To add to all the Awesome work started by Luke I am posting one more that takes a css class value and treats class and alt as optional parameters (valid under ASP.NET 3.5+). This will allow more functionality but reduct the number of overloaded methods needed.

// Extension method
    public static MvcHtmlString ActionImage(this HtmlHelper html, string action,
        string controllerName, object routeValues, string imagePath, string alt = null, string cssClass = null)
    {
        var url = new UrlHelper(html.ViewContext.RequestContext);

        // build the <img> tag
        var imgBuilder = new TagBuilder("img");
        imgBuilder.MergeAttribute("src", url.Content(imagePath));
        if(alt != null)
            imgBuilder.MergeAttribute("alt", alt);
        if (cssClass != null)
            imgBuilder.MergeAttribute("class", cssClass);

        string imgHtml = imgBuilder.ToString(TagRenderMode.SelfClosing);

        // build the <a> tag
        var anchorBuilder = new TagBuilder("a");

        anchorBuilder.MergeAttribute("href", url.Action(action, controllerName, routeValues));
        anchorBuilder.InnerHtml = imgHtml; // include the <img> tag inside
        string anchorHtml = anchorBuilder.ToString(TagRenderMode.Normal);

        return MvcHtmlString.Create(anchorHtml);
    }

slide modification changed Helper

     public static IHtmlString ActionImageLink(this HtmlHelper html, string action, object routeValues, string styleClass, string alt)
    {
        var url = new UrlHelper(html.ViewContext.RequestContext);
        var anchorBuilder = new TagBuilder("a");
        anchorBuilder.MergeAttribute("href", url.Action(action, routeValues));
        anchorBuilder.AddCssClass(styleClass);
        string anchorHtml = anchorBuilder.ToString(TagRenderMode.Normal);

        return new HtmlString(anchorHtml);
    }

CSS Class

.Edit {
       background: url('../images/edit.png') no-repeat right;
       display: inline-block;
       height: 16px;
       width: 16px;
      }

Create the link just pass the class name

     @Html.ActionImageLink("Edit", new { id = item.ID }, "Edit" , "Edit") 

I have joined the answer from Lucas and "ASP.NET MVC Helpers, Merging two object htmlAttributes together" and plus controllerName to following code:

// Sample usage in CSHTML

 @Html.ActionImage("Edit",
       "EditController"
        new { id = MyId },
       "~/Content/Images/Image.bmp",
       new { width=108, height=129, alt="Edit" })

And the extension class for the code above:

using System.Collections.Generic;
using System.Reflection;
using System.Web.Mvc;

namespace MVC.Extensions
{
    public static class MvcHtmlStringExt
    {
        // Extension method
        public static MvcHtmlString ActionImage(
          this HtmlHelper html,
          string action,
          string controllerName,
          object routeValues,
          string imagePath,
          object htmlAttributes)
        {
            //https://stackoverflow.com/questions/4896439/action-image-mvc3-razor
            var url = new UrlHelper(html.ViewContext.RequestContext);

            // build the <img> tag
            var imgBuilder = new TagBuilder("img");
            imgBuilder.MergeAttribute("src", url.Content(imagePath));

            var dictAttributes = htmlAttributes.ToDictionary();

            if (dictAttributes != null)
            {
                foreach (var attribute in dictAttributes)
                {
                    imgBuilder.MergeAttribute(attribute.Key, attribute.Value.ToString(), true);
                }
            }                        

            string imgHtml = imgBuilder.ToString(TagRenderMode.SelfClosing);

            // build the <a> tag
            var anchorBuilder = new TagBuilder("a");
            anchorBuilder.MergeAttribute("href", url.Action(action, controllerName, routeValues));
            anchorBuilder.InnerHtml = imgHtml; // include the <img> tag inside            
            string anchorHtml = anchorBuilder.ToString(TagRenderMode.Normal);

            return MvcHtmlString.Create(anchorHtml);
        }

        public static IDictionary<string, object> ToDictionary(this object data)
        {
            //https://stackoverflow.com/questions/6038255/asp-net-mvc-helpers-merging-two-object-htmlattributes-together

            if (data == null) return null; // Or throw an ArgumentNullException if you want

            BindingFlags publicAttributes = BindingFlags.Public | BindingFlags.Instance;
            Dictionary<string, object> dictionary = new Dictionary<string, object>();

            foreach (PropertyInfo property in
                     data.GetType().GetProperties(publicAttributes))
            {
                if (property.CanRead)
                {
                    dictionary.Add(property.Name, property.GetValue(data, null));
                }
            }
            return dictionary;
        }
    }
}

This would be work very fine

<a href="<%:Url.Action("Edit","Account",new {  id=item.UserId }) %>"><img src="../../Content/ThemeNew/images/edit_notes_delete11.png" alt="Edit" width="25px" height="25px" /></a>