12 files declare their use of ImageInterface in Zircon Profile 8

ConvertImageEffect.php in core/modules/image/src/Plugin/ImageEffect/ConvertImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\ConvertImageEffect.

CropImageEffect.php in core/modules/image/src/Plugin/ImageEffect/CropImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\CropImageEffect.

DesaturateImageEffect.php in core/modules/image/src/Plugin/ImageEffect/DesaturateImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\DesaturateImageEffect.

ImageEffectInterface.php in core/modules/image/src/ImageEffectInterface.php

Contains \Drupal\image\ImageEffectInterface.

NullTestImageEffect.php in core/modules/image/tests/modules/image_module_test/src/Plugin/ImageEffect/NullTestImageEffect.php

Contains \Drupal\image_module_test\Plugin\ImageEffect\NullTestImageEffect.

ResizeImageEffect.php in core/modules/image/src/Plugin/ImageEffect/ResizeImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\ResizeImageEffect.

responsive_image.module in core/modules/responsive_image/responsive_image.module

Responsive image display formatter for image fields.

RotateImageEffect.php in core/modules/image/src/Plugin/ImageEffect/RotateImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\RotateImageEffect.

ScaleAndCropImageEffect.php in core/modules/image/src/Plugin/ImageEffect/ScaleAndCropImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\ScaleAndCropImageEffect.

ScaleImageEffect.php in core/modules/image/src/Plugin/ImageEffect/ScaleImageEffect.php

Contains \Drupal\image\Plugin\ImageEffect\ScaleImageEffect.

ToolkitGdTest.php in core/modules/system/src/Tests/Image/ToolkitGdTest.php

Contains \Drupal\system\Tests\Image\ToolkitGdTest.

UriDependentTestImageEffect.php in core/modules/image/tests/modules/image_module_test/src/Plugin/ImageEffect/UriDependentTestImageEffect.php

Contains \Drupal\image_module_test\Plugin\ImageEffect\UriDependentTestImageEffect.