<SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel:=True)> _
<SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel:=True)> _
Public Class ImageFieldValue
    Inherits HtmlTagValue

Dim instance As ImageFieldValue

[SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel=true)] 
[SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel=true)] 
public class ImageFieldValue : HtmlTagValue

using SPListItem = Microsoft.SharePoint.SPListItem;
using ImageFieldValue = Microsoft.SharePoint.Publishing.Fields.ImageFieldValue;

namespace Microsoft.SDK.SharePointServer.Samples
{
    public static class ImageFieldValueSamples
    {
    // You can change any of the following data that are set into the ImageFieldValue
    private const string NewImageUrl = "/SiteCollectionImages/SampleImage.jpg";
    private const string NewHyperlink = "/Pages/SamplePage.aspx";
    private const bool NewOpenHyperlinkInNewWindow = true;
    private const string NewAlignment = "right";
    private const string NewAlternateText = "Sample alternate text for the image";
    private const int NewBorderWidth = 4;
    private const int NewHeight = 100;
    private const int NewWidth = 150;
    private const int NewHorizontalSpacing = 10;
    private const int NewVerticalSpacing = 15;

    // You can change the following default ImageFieldValue HTML
    private const string DefaultImageFieldValueHtml = "<A href=\"/Pages/SamplePage.aspx\"><IMG src=\"/SiteCollectionImages/SampleImage.jpg\" alt=\"Default ALT attribute value\"></a>";

    public static string GetAndSetImageFieldValue(
    SPListItem listItemWithImageField,
    string imageFieldName)
    {
      if (null == listItemWithImageField)
      {
        throw new System.ArgumentNullException("listItemWithImageField", "The listItemWithImageField argument must be a valid SPListItem");
      }

      if (string.IsNullOrEmpty(imageFieldName))
      {
         throw new System.ArgumentNullException("imageFieldName", "The imageFieldName argument must be a valid image field name on the SPListItem");
      }

      // Retrieve the current value from an SPListItem with a
      // column of the ImageField type with the name imageFieldName
      ImageFieldValue currentFieldValue = 
      listItemWithImageField[imageFieldName] as ImageFieldValue;

      // If there is no current value then construct a new empty value
      if (null == currentFieldValue)
      {
         currentFieldValue = new ImageFieldValue();
      }

      // If this property is not set to a value then the ToString() for
      // the ImageFieldValue returns String.Empty and nothing is stored
      // in the field value when it is set back into the SPListItem.
      currentFieldValue.ImageUrl = NewImageUrl;

      // These properties are all optional for an ImageFieldValue
      currentFieldValue.Hyperlink = NewHyperlink;
      currentFieldValue.OpenHyperlinkInNewWindow = NewOpenHyperlinkInNewWindow;
      currentFieldValue.Alignment = NewAlignment;
      currentFieldValue.AlternateText = NewAlternateText;
      currentFieldValue.BorderWidth = NewBorderWidth;
      currentFieldValue.Height = NewHeight;
      currentFieldValue.Width = NewWidth;
      currentFieldValue.HorizontalSpacing = NewHorizontalSpacing;
      currentFieldValue.VerticalSpacing = NewVerticalSpacing;

      // The changes to the properties of the ImageFieldValue object are
      // local to this specific object instance and not stored in the SPListItem.
      // To store the changes the value must be set back in to the SPListItem field value.
     listItemWithImageField[imageFieldName] = currentFieldValue;
     listItemWithImageField.Update();

     // The ToString() returns the HTML that reflects the new ImageFieldValue properties
     return currentFieldValue.ToString();
    }
  }
}