<?php
// get the area object using the area name
$areaObject = $c->getArea('Header Site Title');
// get the blocks in the area object
$areaBlocks = $areaObject->getAreaBlocks();
// loop through the array of area blocks
foreach ($areaBlocks as $block) {
    // if the current block has the block handle of "image"
    if ($block->btHandle == 'image') {
        // get the block's instance
        $blockInstance = $block->getInstance();
        // use the Image block controller getFileID() method to see if there is a selected image
        if ($blockInstance->getFileID()) {
            // if there is a selected image, get its file ID
            $fileID = $blockInstance->getFileID();
            // using the file ID get the file object
            $file = File::getByID($fileID);
            // with the file object you can get its relative path
            echo $file->getRelativePath();
        }
    }
}
?>