Choose the image effect. Will use Thumbnail style option at Blazy formatters for the placeholder with fallback to core Thumbnail style. For best results: use similar aspect ratio for both Thumbnail and Image styles; adjust Offset and or threshold; the smaller the better. Use <code>hook_blazy_image_effects_alter()</code> to add more effects -- curtain, fractal, slice, whatever. <b>Limitations</b>: Best with a proper Aspect ratio option as otherwise collapsed image. Be sure to add one. If not, add regular CSS <code>min-height</code> for each mediaquery. The Placeholder option is still respected. It is permanently cached, be sure to clear cache if your or a module's provided additional altered data do not appear here. <ul><li>To avoid complications, it will be disabled when being unlazy: no JS, iframe only, sandboxed, etc. since it requires lazy load as a trigger.</li></ul>