Craft\ImagerService::_createTargetFilename PHP Method

    private function _createTargetFilename($filename, $extension, $transform)
    {
        $hashFilename = $this->getSetting('hashFilename', $transform);
        // generate unique string base on transform
        $transformFileString = $this->_createTransformFilestring($transform);
        $configOverridesString = $this->configModel->getConfigOverrideString();
        if ($hashFilename) {
            if (is_string($hashFilename)) {
                if ($hashFilename == 'postfix') {
                    return $filename . '_' . md5($transformFileString . $configOverridesString) . '.' . $extension;
                } else {
                    return md5($filename . $transformFileString . $configOverridesString) . '.' . $extension;
                }
            } else {
                return md5($filename . $transformFileString . $configOverridesString) . '.' . $extension;
            }
        } else {
            return $filename . $transformFileString . $configOverridesString . '.' . $extension;
        }
    }