Show category Image in main Navigation in magento

In Model file. (/app/code/core/Mage/Catalog/Model/Observer.php)

Update following code in Function Name: _addCategoriesToMenu

 $categoryData = array( 
        'name' => $category->getName(),
        'id' => $nodeId,
        'url' => Mage::helper('catalog/category')->getCategoryUrl($category),
        'is_active' => $this->_isActiveMenuCategory($category),
        'thumbnail' => Mage::getModel('catalog/category')->load($category->getId())->getThumbnail()

    );

Then go into Html folder. (app/code/core/Mage/Page/Block/Html/Topmenu.php)

Update the following line of code at line 131 in

Function name: _getHtml

replace :

$html .= '<li ' . $this->_getRenderedMenuItemAttributes($child) . '>';

            $html .= '<a href="' . $child->getUrl() . '" ' . $outermostClassCode . '><span>'

                . $this->escapeHtml($child->getName()) . '</span></a>';

 if ($child->hasChildren()) {

                if (!empty($childrenWrapClass)) {

                    $html .= '<div class="' . $childrenWrapClass . '">';

                }

                $html .= '<ul class="level' . $childLevel . '">';

                $html .= $this->_getHtml($child, $childrenWrapClass);

                $html .= '</ul>';

                if (!empty($childrenWrapClass)) {

                    $html .= '</div>';

                }

            }

to

    $urls = Mage::getBaseUrl('media').'catalog/category/'.$child->getData('thumbnail');
    $img = '<img src="'.$urls.'" />';

$html .= '<li ' . $this->_getRenderedMenuItemAttributes($child) . '>';
$html .= '<a href="' . $child->getUrl() . '" ' . $outermostClassCode . '><span>'
    . $this->escapeHtml($child->getName()) . ' </span>  </a>';

 if ($child->hasChildren()) {
                if (!empty($childrenWrapClass)) {
                    $html .= '<div class="' . $childrenWrapClass . '">';
                }
                $html .= '<ul class="level' . $childLevel . '">';
    $html.= $img;
                $html .= $this->_getHtml($child, $childrenWrapClass);
                $html .= '</ul>';

                if (!empty($childrenWrapClass)) {
                    $html .= '</div>';
                }
            }

thats all......