Model/Config.php
public function isImageOptimizationEnabled()
    {
        if ($this->isFastlyEnabled() !== true) {
            return false;
        }

        return $this->_scopeConfig->isSetFlag(self::XML_FASTLY_IMAGE_OPTIMIZATIONS);
    }
public function isImageOptimizationEnabled()
    {
        if ($this->isFastlyEnabled() !== true) {
            return false;
        }

        return $this->_scopeConfig->isSetFlag(self::XML_FASTLY_IMAGE_OPTIMIZATIONS);
    }
Determines should Image optimization be used

@return bool