diff --git a/lib/Cpdf.php b/lib/Cpdf.php
index <HASH>..<HASH> 100644
--- a/lib/Cpdf.php
+++ b/lib/Cpdf.php
@@ -5763,7 +5763,7 @@ EOT;
                     if ($eight_bit) {
                         // with gamma correction
                         $gammacorr = 2.2;
-                        $pixel = pow((((127 - $alpha) * 255 / 127) / 255), $gammacorr) * 255;
+                        $pixel = round(pow((((127 - $alpha) * 255 / 127) / 255), $gammacorr) * 255);
                     } else {
                         // without gamma correction
                         $pixel = (127 - $alpha) * 2;
Round pixel color for 8-bit PNG with transparency

When processing the alpha channel in CPDF. Addresses PHP <I> compatibility issue.