Images

Render array for an image style

$render = [

'#theme' => 'image_style',

'#style_name' => 'thumbnail',

'#uri' => 'public://my-image.png',

];

Image style, get URL (full URL including http://)

$style = \Drupal::entityTypeManager()->getStorage('image_style')->load('thumbnail');

$image_url = $style->buildUrl('public://du_content_gallery-article.jpg');

Image style, get URI (public://path-to-image-style)

$style = ImageStyle::load('thumbnail');

$image_url = $style->buildUri('public://du_content_gallery-article.jpg');