You'll need to loop through the images and print it:
foreach($json['artist']['similar']['artist'] as $item) {
print $item['name'];
print '<br>';
for ($i=0; $i < count($item['image']); $i++) {
echo $item['image'][$i]['#text']."<br>";
}
}
To print them only if they're of size large or extra large, you can use a simple if
statement:
for ($i=0; $i < count($item['image']); $i++) {
echo $item['image'][$i]['#text']."<br>";
if($item['image'][$i]['size'] == 'extralarge') {
echo $item['image'][$i]['#text']."<br>";
}
}