Image in gridview in yii2

Question

How to put an image in GridView in yii2?I have the following code. But its not displaying the image as it is not giving any image url. Where to put the image url?

 <?php echo GridView::widget([
    'dataProvider' => $dataProvider,
    'filterModel' => $searchModel,
    'columns' => [
        ['class' => 'yii\grid\SerialColumn'],

        'c_id',
        'name:ntext',
        'description:ntext',
        array(
                'format' => 'image',
               'attribute'=>'logo',

),

        ['class' => 'yii\grid\ActionColumn'],
    ],
]); ?>