ImageField.php

<?php

namespace Drupal\image\Plugin\migrate\field\d7;

use Drupal\migrate\Plugin\MigrationInterface;
use Drupal\migrate_drupal\Plugin\migrate\field\FieldPluginBase;

/**
 * @MigrateField(
 *   id = "image",
 *   core = {7},
 *   source_module = "image",
 *   destination_module = "image"
 * )
 */
class ImageField extends FieldPluginBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFieldWidgetMap() {
        return [
            'image' => 'image_default',
            'image_miw' => 'image_image',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function defineValueProcessPipeline(MigrationInterface $migration, $field_name, $data) {
        $process = [
            'plugin' => 'sub_process',
            'source' => $field_name,
            'process' => [
                'target_id' => 'fid',
                'alt' => 'alt',
                'title' => 'title',
                'width' => 'width',
                'height' => 'height',
            ],
        ];
        $migration->mergeProcessOfProperty($field_name, $process);
    }

}