Display an image in the admin grid in magento 2

Your ui component xml should have this added:

<column name="image" class="Your\Modulename\Ui\Component\Listing\Column\Thumbnail">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="component" xsi:type="string">Magento_Ui/js/grid/columns/thumbnail</item>
            <item name="sortable" xsi:type="boolean">false</item>
            <item name="altField" xsi:type="string">title</item>
            <item name="has_preview" xsi:type="string">1</item>
            <item name="label" xsi:type="string" translate="true">Thumbnail</item>
        </item>
    </argument>
</column>

..and then in Your\Modulename\Ui\Component\Listing\Column\Thumbnail.php something similar to this:

<?php
namespace Your\Modulename\Ui\Component\Listing\Column;

use Magento\Catalog\Helper\Image;
use Magento\Framework\UrlInterface;
use Magento\Framework\View\Element\UiComponentFactory;
use Magento\Framework\View\Element\UiComponent\ContextInterface;
use Magento\Store\Model\StoreManagerInterface;
use Magento\Ui\Component\Listing\Columns\Column;

class Thumbnail extends Column
{
    const ALT_FIELD = 'title';

    /**
     * @var \Magento\Store\Model\StoreManagerInterface
     */
    protected $storeManager;

    /**
     * @param ContextInterface $context
     * @param UiComponentFactory $uiComponentFactory
     * @param Image $imageHelper
     * @param UrlInterface $urlBuilder
     * @param StoreManagerInterface $storeManager
     * @param array $components
     * @param array $data
     */
    public function __construct(
        ContextInterface $context,
        UiComponentFactory $uiComponentFactory,
        Image $imageHelper,
        UrlInterface $urlBuilder,
        StoreManagerInterface $storeManager,
        array $components = [],
        array $data = []
    ) {
        $this->storeManager = $storeManager;
        $this->imageHelper = $imageHelper;
        $this->urlBuilder = $urlBuilder;
        parent::__construct($context, $uiComponentFactory, $components, $data);
    }

    /**
     * Prepare Data Source
     *
     * @param array $dataSource
     * @return array
     */
    public function prepareDataSource(array $dataSource)
    {
        if(isset($dataSource['data']['items'])) {
            $fieldName = $this->getData('name');
            foreach($dataSource['data']['items'] as & $item) {
                $url = '';
                if($item[$fieldName] != '') {
                    $url = $this->storeManager->getStore()->getBaseUrl(
                        \Magento\Framework\UrlInterface::URL_TYPE_MEDIA
                    ).'pathtoyourimage/'.$item[$fieldName];
                }
                $item[$fieldName . '_src'] = $url;
                $item[$fieldName . '_alt'] = $this->getAlt($item) ?: '';
                $item[$fieldName . '_link'] = $this->urlBuilder->getUrl(
                    'your_module/yourentity/edit',
                    ['yourentity_id' => $item['yourentity_id']]
                );
                $item[$fieldName . '_orig_src'] = $url;
            }
        }

        return $dataSource;
    }

    /**
     * @param array $row
     *
     * @return null|string
     */
    protected function getAlt($row)
    {
        $altField = $this->getData('config/altField') ?: self::ALT_FIELD;
        return isset($row[$altField]) ? $row[$altField] : null;
    }
}

I hope that helps!

In your grid.php define like below

$this->addColumn(
    'image',
    array(
        'header' => __('Image'),
        'index' => 'image',
        'renderer'  => '\Vendorname\Modulename\Block\Adminhtml\Modulename\Grid\Renderer\Image',
    )
);

Create Image.php under

\Vendorname\Modulename\Block\Adminhtml\Modulename\Grid\Renderer\

and paste below code

namespace Vendorname\Modulename\Block\Adminhtml\Modulename\Grid\Renderer;

class Image extends \Magento\Backend\Block\Widget\Grid\Column\Renderer\AbstractRenderer
{
    protected $_storeManager;


    public function __construct(
        \Magento\Backend\Block\Context $context,
        \Magento\Store\Model\StoreManagerInterface $storeManager,      
        array $data = []
    ) {
        parent::__construct($context, $data);
        $this->_storeManager = $storeManager;        
    }


    public function render(\Magento\Framework\DataObject $row)
    {
        $img;
        $mediaDirectory = $this->_storeManager->getStore()->getBaseUrl(
           \Magento\Framework\UrlInterface::URL_TYPE_MEDIA
       );
        if($this->_getValue($row)!=''):
            $imageUrl = $mediaDirectory.$this->_getValue($row);
            $img='<img src="'.$imageUrl.'" width="100" height="100"/>';
        else:
            $img='<img src="'.$mediaDirectory.'Modulename/no-img.jpg'.'" width="100" height="100"/>';
        endif;
        return $img;
    }
}

Just add this tag in you ui_component layout file

<column name="logo" class="NAMESPACE\MODULENAME\Ui\Component\Listing\Columns\Logo">
    <argument name="data" xsi:type="array">
        <item name="config" xsi:type="array">
            <item name="component" xsi:type="string">Magento_Ui/js/grid/columns/thumbnail</item>
            <!--<item name="add_field" xsi:type="boolean">true</item>-->
            <item name="sortable" xsi:type="boolean">false</item>
            <item name="altField" xsi:type="string">name</item>
            <item name="has_preview" xsi:type="string">1</item>
            <item name="label" xsi:type="string" translate="true">Brand Logo</item>
        </item>
    </argument>
</column>

and create this new file which we have assign in our ui_component column

<?php
namespace NAMESPACE\MODULENAME\Ui\Component\Listing\Columns;

use Magento\Framework\View\Element\UiComponentFactory;
use Magento\Framework\View\Element\UiComponent\ContextInterface;

class Logo extends \Magento\Ui\Component\Listing\Columns\Column
{
    const NAME = 'logo';

    const ALT_FIELD = 'name';

    protected $_storeManager;

    public function __construct(
        ContextInterface $context,
        UiComponentFactory $uiComponentFactory,        
        \Magento\Framework\UrlInterface $urlBuilder,
        array $components = [],
        array $data = [],
        \Magento\Store\Model\StoreManagerInterface $storeManager
    ) {        
        parent::__construct($context, $uiComponentFactory, $components, $data);
        $this->_storeManager = $storeManager;
        $this->urlBuilder = $urlBuilder;
    }

    /**
    * Prepare Data Source
    *
    * @param array $dataSource
    * @return array
    */
    public function prepareDataSource(array $dataSource)
    {
        if (isset($dataSource['data']['items'])) {
            $fieldName = $this->getData('name');
            foreach ($dataSource['data']['items'] as & $item) {
                $mediaRelativePath=$this->_storeManager->getStore()->getBaseUrl(\Magento\Framework\UrlInterface::URL_TYPE_MEDIA);
                $logoPath=$mediaRelativePath.$item['logo'];
                $item[$fieldName . '_src'] = $logoPath;
                $item[$fieldName . '_alt'] = $this->getAlt($item);
                $item[$fieldName . '_link'] = $this->urlBuilder->getUrl(
                    'brand/manage/edit',
                    ['brand_id' => $item['brand_id'], 'store' => $this->context->getRequestParam('store')]
                );
                $item[$fieldName . '_orig_src'] = $logoPath;

            }
        }

        return $dataSource;
    }

    /**
    * @param array $row
    *
    * @return null|string
    */
    protected function getAlt($row)
    {
        $altField = self::ALT_FIELD;
        return isset($row[$altField]) ? $row[$altField] : null;
    }
}

In prepareDataSource function you will get each column object.

Hope this will help you.