diff --git a/src/ResizerParamsParser.php b/src/ResizerParamsParser.php
index 15aa608..d6b72de 100755
--- a/src/ResizerParamsParser.php
+++ b/src/ResizerParamsParser.php
@@ -10,18 +10,44 @@ class ResizerParamsParser
 {
 	use SmartObject;
 
-	private const PATTERN = '~
-		^(?:auto|                        # use the image as-is, only compress/convert
-			(?:(ifresize)-)?              # ifresize modifier
-			([lcr]?)([1-9][0-9]*)?        # width modifer and dimension
-			x                             # divider
-			([tcb]?)([1-9][0-9]*)?        # height modifier and dimension
-			(!?)                          # force dimensions, disregard aspect ratio
-			(?:-hm([+-]?[0-9]*))?         # horizontal margin, unused
-			(?:-vm([+-]?[0-9]*))?         # vertical margin, unused
-			(?:-q([0-9][0-9]?|100))?      # quality, 0-100
-		)$
-	~x';
+	public const PATTERN_IR = 'ir/';
+	public const PATTERN_AUTO = '?:auto'; 										# use the image as-is, only compress/convert
+	public const PATTERN_IFRESIZE = '(?:(ifresize)-)?';					# ifresize modifier
+	public const PATTERN_WIDTH_MOD = '([lcr]?)([1-9][0-9]*)?';			# width modifer and dimension
+	public const PATTERN_DIVIDER = 'x';											# divider
+	public const PATTERN_HEIGHT_MOD = '([tcb]?)([1-9][0-9]*)?';			# height modifier and dimension
+	public const PATTERN_FORCE_DIMS = '(!?)';									# force dimensions, disregard aspect ratio
+	public const PATTERN_MARGIN_H = '(?:-hm([+-]?[0-9]*))?';				# horizontal margin, unused
+	public const PATTERN_MARGIN_V = '(?:-vm([+-]?[0-9]*))?';				# vertical margin, unused
+	public const PATTERN_MARGIN_Q = '(?:-q([0-9][0-9]?|100))?';			# quality, 0-100
+
+	public const PATTERN_PARAMS = '(' .
+		self::PATTERN_AUTO . '|' .
+		self::PATTERN_IFRESIZE .
+		self::PATTERN_WIDTH_MOD .
+		self::PATTERN_DIVIDER .
+		self::PATTERN_HEIGHT_MOD .
+		self::PATTERN_FORCE_DIMS .
+		self::PATTERN_MARGIN_H .
+		self::PATTERN_MARGIN_V .
+		self::PATTERN_MARGIN_Q .
+	')';
+
+	public const PATTERN = '~^' . self::PATTERN_PARAMS . '$~';
+	public const PATTERN_JS = self::PATTERN_PARAMS;
+
+	// public const PATTERN = '~
+	// 	^(?:auto|                        # use the image as-is, only compress/convert
+	// 		(?:(ifresize)-)?              # ifresize modifier
+	// 		([lcr]?)([1-9][0-9]*)?        # width modifer and dimension
+	// 		x                             # divider
+	// 		([tcb]?)([1-9][0-9]*)?        # height modifier and dimension
+	// 		(!?)                          # force dimensions, disregard aspect ratio
+	// 		(?:-hm([+-]?[0-9]*))?         # horizontal margin, unused
+	// 		(?:-vm([+-]?[0-9]*))?         # vertical margin, unused
+	// 		(?:-q([0-9][0-9]?|100))?      # quality, 0-100
+	// 	)$
+	// ~x';
 
 	private ResizerParams $params;
 
@@ -45,8 +71,8 @@ public function parseParams(string $rawParams): ResizerParams
 		$ifresize = (bool) ($matches[1] ?? '');
 		$horizontal = $matches[2] ?? '';
 		$vertical = $matches[4] ?? '';
-		$width = $this->parseNumericValueToIntOrNull($matches[3] ?? '');
-		$height = $this->parseNumericValueToIntOrNull($matches[5] ?? '');
+		$width = $this->parseNumericValueToPositiveIntOrNull($matches[3] ?? '');
+		$height = $this->parseNumericValueToPositiveIntOrNull($matches[5] ?? '');
 		$suffix = $matches[6] ?? '';
 		$horizontalMargin = $matches[7] ?? '';
 		$verticalMargin = $matches[8] ?? '';
@@ -72,13 +98,32 @@ public function getParams(): ResizerParams
 	}
 
 
-	/** @return int|null */
+	/** @return int<0,100>|null */
 	private function parseNumericValueToIntOrNull(string $value): ?int
 	{
 		if (strlen($value) === 0) {
 			return null;
 		}
 
+		if (is_numeric($value)) {
+			$int = (int) $value;
+
+			if ($int >= 0 && $int <= 100) {
+				return $int;
+			}
+		}
+
+		return null;
+	}
+
+
+	/** @return positive-int|null */
+	private function parseNumericValueToPositiveIntOrNull(string $value): ?int
+	{
+		if (strlen($value) === 0) {
+			return null;
+		}
+
 		if (is_numeric($value)) {
 			$int = (int) $value;