diff --git a/src/Smalot/PdfParser/PDFObject.php b/src/Smalot/PdfParser/PDFObject.php
index f2660156..d1b8846f 100644
--- a/src/Smalot/PdfParser/PDFObject.php
+++ b/src/Smalot/PdfParser/PDFObject.php
@@ -224,6 +224,66 @@ private function formatContent(?string $content): string
             return '';
         }
 
+        // Find all inline image content and replace them so they aren't
+        // affected by the next steps
+        $pdfInlineImages = [];
+        $offsetBI = 0;
+        while (preg_match('/\sBI\s(\/.+?)\sID\s(.+?)\sEI(?=\s|$)/s', $content, $text, \PREG_OFFSET_CAPTURE, $offsetBI)) {
+            // Attempt to detemine if this instance of the 'BI' command
+            // actually occured within a (string) using the following
+            // steps:
+
+            // Step 1: Remove any escaped parentheses from the alleged
+            // image characteristics data
+            $para = str_replace(['\\(', '\\)'], '', $text[1][0]);
+
+            // Step 2: Remove all correctly ordered and balanced
+            // parentheses from (strings)
+            do {
+                $paraTest = $para;
+                $para = preg_replace('/\(([^()]*)\)/', '$1', $paraTest);
+            } while ($para != $paraTest);
+
+            $paraOpen = strpos($para, '(');
+            $paraClose = strpos($para, ')');
+
+            // Check: If the remaining text contains a close parenthesis
+            // ')' AND it occurs before any open parenthesis, then we
+            // are almost certain to be inside a (string)
+            if (0 < $paraClose && (false === $paraOpen || $paraClose < $paraOpen)) {
+                // Bump the search offset forward and match again
+                $offsetBI = (int) $text[1][1];
+                continue;
+            }
+
+            // Step 3: Double check that this is actually inline image
+            // data by parsing the alleged image characteristics as a
+            // dictionary
+            $dict = $this->parseDictionary('<<'.$text[1][0].'>>');
+
+            // Check if an image Width and Height are set in the dict
+            if ((isset($dict['W']) || isset($dict['Width']))
+                && (isset($dict['H']) || isset($dict['Height']))) {
+                $id = uniqid('IMAGE_', true);
+                $pdfInlineImages[$id] = [
+                    preg_replace(['/\r\n/', '/\r/', '/\n/'], ' ', $text[1][0]),
+                    preg_replace(['/\r\n/', '/\r/', '/\n/'], '', $text[2][0]),
+                ];
+                $content = preg_replace(
+                    '/'.preg_quote($text[0][0], '/').'/',
+                    '^^^'.$id.'^^^',
+                    $content,
+                    1
+                );
+            } else {
+                // If there was no valid dictionary, or a height and width
+                // weren't specified, then we don't know what this is, so
+                // just leave it alone; bump the search offset forward and
+                // match again
+                $offsetBI = (int) $text[1][1];
+            }
+        }
+
         // Find all strings () and replace them so they aren't affected
         // by the next steps
         $pdfstrings = [];
@@ -260,7 +320,7 @@ private function formatContent(?string $content): string
         // Find all dictionary << >> commands and replace them so they
         // aren't affected by the next steps
         $dictstore = [];
-        while (preg_match('/(<<.*?>> *)(BDC|BMC|DP|MP)/', $content, $dicttext)) {
+        while (preg_match('/(<<.*?>> *)(BDC|BMC|DP|MP)/s', $content, $dicttext)) {
             $dictid = uniqid('DICT_', true);
             $dictstore[$dictid] = $dicttext[1];
             $content = preg_replace(
@@ -319,6 +379,16 @@ private function formatContent(?string $content): string
             $content = str_replace('@@@'.$id.'@@@', $text, $content);
         }
 
+        // Restore the original content of any inline images
+        $pdfInlineImages = array_reverse($pdfInlineImages, true);
+        foreach ($pdfInlineImages as $id => $image) {
+            $content = str_replace(
+                '^^^'.$id.'^^^',
+                "\r\nBI\r\n".$image[0]." ID\r\n".$image[1]." EI\r\n",
+                $content
+            );
+        }
+
         $content = trim(preg_replace(['/(\r\n){2,}/', '/\r\n +/'], "\r\n", $content));
 
         return $content;
diff --git a/tests/PHPUnit/Integration/PDFObjectTest.php b/tests/PHPUnit/Integration/PDFObjectTest.php
index 025c11b1..947a6944 100644
--- a/tests/PHPUnit/Integration/PDFObjectTest.php
+++ b/tests/PHPUnit/Integration/PDFObjectTest.php
@@ -286,6 +286,43 @@ public function testFormatContent(): void
         $this->assertStringContainsString('Marko Nestorović PR', $pages[0]->getText());
     }
 
+    /**
+     * Check that inline image data does not corrupt the stream
+     *
+     * @see: https://github.com/smalot/pdfparser/issues/691
+     */
+    public function testFormatContentInlineImages(): void
+    {
+        $formatContent = new \ReflectionMethod('Smalot\PdfParser\PDFObject', 'formatContent');
+        $formatContent->setAccessible(true);
+
+        $cleaned = $formatContent->invoke(
+            $this->getPdfObjectInstance(new Document()),
+            'BT (This BI /W 258 /H 51 /should not trigger /as a /PDF command) TD ET q 65.30 0 0 18.00 412 707 cm BI /W 544 /H 150
+/BPC 1 /IM true /F [/A85 /Fl] ID Gb"0F_$L6!$j/a\$:ma&h\'JnJJ9S?O_EA-W+%D^ClCH=FP3s5M-gStQm\'5/hc`C?<Q)riWgtEe:Po0dY_-er6$jM@#?n`E+#(sa"0Gk3&K>CqL(^pV$_-er6Ik`"-1]Q ;~> EI Q /F002 10.00 Tf 0.00 Tw 0 g'
+        );
+
+        // PdfParser should not be fooled by Q's in inline image data;
+        // Only one 'Q' command should be found
+        $commandQ = preg_match_all('/Q\r\n/', $cleaned);
+        $this->assertEquals(1, $commandQ);
+
+        // The 'BI' inside a string should not be interpreted as the
+        // beginning of an inline image command
+        $this->assertStringContainsString('(This BI /W 258 /H 51 /should not trigger /as a /PDF command) TD', $cleaned);
+
+        $cleaned = $formatContent->invoke(
+            $this->getPdfObjectInstance(new Document()),
+            'BT (This BI /W 258 /H 51 /should not () \) trigger /as a /PDF command) TD (There is no ID inline image in this data) TD (Nothing but text EI should be found) TD ET'
+        );
+
+        $this->assertEquals('BT'."\r\n".
+'(This BI /W 258 /H 51 /should not () \) trigger /as a /PDF command) TD'."\r\n".
+'(There is no ID inline image in this data) TD'."\r\n".
+'(Nothing but text EI should be found) TD'."\r\n".
+'ET', $cleaned);
+    }
+
     public function testGetSectionsText(): void
     {
         $content = '/Shape <</MCID 1 >>BDC