7 theme calls to theme_image_style()

ImageFieldDisplayTest::testImageFieldSettings in drupal/core/modules/image/lib/Drupal/image/Tests/ImageFieldDisplayTest.php
Tests for image field settings.
ImageFieldDisplayTest::_testImageFieldFormatters in drupal/core/modules/image/lib/Drupal/image/Tests/ImageFieldDisplayTest.php
Test image formatters on node display.
ImageThemeFunctionTest::testImageStyleTheme in drupal/core/modules/image/lib/Drupal/image/Tests/ImageThemeFunctionTest.php
Tests usage of the image style theme function.
image_field_widget_process in drupal/core/modules/image/image.field.inc
An element #process callback for the image_image field type.
PictureFieldDisplayTest::_testPictureFieldFormatters in drupal/core/modules/picture/lib/Drupal/picture/Tests/PictureFieldDisplayTest.php
Test picture formatters on node display.
theme_image_formatter in drupal/core/modules/image/image.field.inc
Returns HTML for an image field formatter.
theme_picture in drupal/core/modules/picture/picture.module
Returns HTML for a picture.