<file path="system/library/image.php">
    <operation error="log">
            <search><![CDATA[if ($this->mime == 'image/gif')]]></search>
            <add position="before"><![CDATA[if ($this->mime == 'image/webp') {
                $this->image = imagecreatefromwebp($file);
            }
            ]]></add>
        </operation>
        <operation error="skip">
            <search><![CDATA[imagedestroy($this->image);]]></search>
            <add position="before"><![CDATA[elseif ($extension == 'webp') {
                            imagewebp($this->image, $file);
            }]]></add>
        </operation>
    </file>
    
    <file path="admin/model/tool/image.php">
    <operation error="log">
            <search><![CDATA[if (!in_array($image_type, array(IMAGETYPE_PNG, IMAGETYPE_JPEG, IMAGETYPE_GIF)))]]></search>
            <add position="replace"><![CDATA[
            if (!in_array($image_type, array(IMAGETYPE_PNG, IMAGETYPE_JPEG, IMAGETYPE_GIF,18)))
            ]]></add>
        </operation>
    </file>
    <file path="catalog/model/tool/image.php">
    <operation error="log">
            <search><![CDATA[if (!in_array($image_type, array(IMAGETYPE_PNG, IMAGETYPE_JPEG, IMAGETYPE_GIF)))]]></search>
            <add position="replace"><![CDATA[
            if (!in_array($image_type, array(IMAGETYPE_PNG, IMAGETYPE_JPEG, IMAGETYPE_GIF,18)))
            ]]></add>
        </operation>
    </file>
        
    <file path="admin/controller/common/filemanager.php">
    <operation error="skip">
            <search><![CDATA[$files = glob($directory . '/' . $filter_name . '*.{jpg,jpeg,png,gif,JPG,JPEG,PNG,GIF}', GLOB_BRACE);]]></search>
            <add position="replace"><![CDATA[
            $files = glob($directory . '/' . $filter_name . '*.{jpg,jpeg,png,gif,webp,JPG,JPEG,PNG,GIF,WEBP}', GLOB_BRACE);
            ]]></add>
        </operation>
        <operation error="skip">
            <search><![CDATA[move_uploaded_file($file['tmp_name'], $directory . '/' . $filename);]]></search>
            <add position="after"><![CDATA[
                                       $isJPG=array('jpg');
                                        if (in_array(utf8_strtolower(utf8_substr(strrchr($filename, '.'), 1)), $isJPG)) {
                                        $save_to_path = $directory . '/' . $filename;
                                        $im = imageCreateFromJpeg($save_to_path);
                                        imagewebp($im, substr_replace($save_to_path , 'webp', strrpos($save_to_path , '.') +1));
                    }
            ]]></add>
        </operation>
    </file>

İster Modifikasyon dosyası ayarla ocmod olarak System klasorune ekle, istersen Manuel bu değişiklikleri yaparsan işini görecektir.