Classes/Tca/Graphics.php
public function getImageFileExtensions(array $settings)
    {
        $languageService = $this->getLanguageService();

        $extensions = GeneralUtility::trimExplode(',', strtolower($GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']), true);
        // We don't consider PDF being an image...
        if ($key = array_search('pdf', $extensions)) {
            unset($extensions[$key]);
        }
        // ... neither SVG since vectorial
        if ($key = array_search('svg', $extensions)) {
            unset($extensions[$key]);
        }
        asort($extensions);

        $elements = [];
        foreach ($extensions as $extension) {
            $label = $languageService->sL('LLL:EXT:image_autoresize/Resources/Private/Language/locallang.xlf:extension.' . $extension);
            $label = $label ? $label : '.' . $extension;
            $elements[] = [$label, $extension];
        }

        $settings['items'] = array_merge($settings['items'], $elements);
    }
public function getImageFileExtensions(array $settings)
    {
        $languageService = $this->getLanguageService();

        $extensions = GeneralUtility::trimExplode(',', strtolower($GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']), true);
        // We don't consider PDF being an image...
        if ($key = array_search('pdf', $extensions)) {
            unset($extensions[$key]);
        }
        // ... neither SVG since vectorial
        if ($key = array_search('svg', $extensions)) {
            unset($extensions[$key]);
        }
        asort($extensions);

        $elements = [];
        foreach ($extensions as $extension) {
            $label = $languageService->sL('LLL:EXT:image_autoresize/Resources/Private/Language/locallang.xlf:extension.' . $extension);
            $label = $label ? $label : '.' . $extension;
            $elements[] = [$label, $extension];
        }

        $settings['items'] = array_merge($settings['items'], $elements);
    }
Prepares a list of image file extensions supported by the
current TYPO3 install.

@param array $settings content element configuration
@return void