code: public static function img($src, $options = [])
      {
          $options['src'] = Url::to($src);
  
          if (isset($options['srcset']) && is_array($options['srcset'])) {
              $srcset = [];
              foreach ($options['srcset'] as $descriptor => $url) {
                  $srcset[] = Url::to($url) . ' ' . $descriptor;
              }
              $options['srcset'] = implode(',', $srcset);
          }
  
          if (!isset($options['alt'])) {
              $options['alt'] = '';
          }
  
          return static::tag('img', '', $options);
      }
docs: Generates an image tag.
  @param array|string $src the image URL. This parameter will be processed by [[Url::to()]].
  @param array $options the tag options in terms of name-value pairs. These will be rendered as
  the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
  If a value is null, the corresponding attribute will not be rendered.
  See [[renderTagAttributes()]] for details on how attributes are being rendered.
  
  Since version 2.0.12 It is possible to pass the `srcset` option as an array which keys are
  descriptors and values are URLs. All URLs will be processed by [[Url::to()]].
  @return string the generated image tag.