muthu32 · December 31, 2020 06:07 · Dec 31, 2020
diff --git a/image compare.php b/image compare.php
@@ -0,0 +1,107 @@
+<?php
+/**
+* Image Comparing Function (C)2011 Robert Lerner, All Rights Reserved
+* $image1                     STRING/RESOURCE          Filepath and name to PNG or passed image resource handle
+* $image2                    STRING/RESOURCE          Filepath and name to PNG or passed image resource handle
+* $RTolerance               INTEGER (0-/+255)     Red Integer Color Deviation before channel flag thrown
+* $GTolerance               INTEGER (0-/+255)     Green Integer Color Deviation before channel flag thrown
+* $BTolerance               INTEGER (0-/+255)     Blue Integer Color Deviation before channel flag thrown
+* $WarningTolerance     INTEGER (0-100)          Percentage of channel differences before warning returned
+* $ErrorTolerance          INTEGER (0-100)          Percentage of channel difference before error returned
+ 
+*/
+function imageCompare($image1, $image2, $RTolerance=0, $GTolerance=0, $BTolerance=0, $WarningTolerance=1, $ErrorTolerance=5)
+     {
+     if (is_resource($image1))
+          $im = $image1;
+     else
+          if (!$im = imagecreatefrompng($image1))
+               trigger_error("Image 1 could not be opened",E_USER_ERROR);
+
+     if (is_resource($image2))
+          $im2 = $image2;
+     else
+          if (!$im2 = imagecreatefrompng($image2))
+               trigger_error("Image 2 could not be opened",E_USER_ERROR);
+
+
+
+     $OutOfSpec = 0;
+
+     if (imagesx($im)!=imagesx($im2))
+          die("Width does not match.");
+     if (imagesy($im)!=imagesy($im2))
+          die("Height does not match.");
+
+
+     //By columns
+     for ($width=0;$width<=imagesx($im)-1;$width++)
+          {
+          for ($height=0;$height<=imagesy($im)-1;$height++)
+               {
+               $rgb = imagecolorat($im, $width, $height);
+               $r1 = ($rgb >> 16) & 0xFF;
+               $g1 = ($rgb >> 8) & 0xFF;
+               $b1 = $rgb & 0xFF;
+
+               $rgb = imagecolorat($im2, $width, $height);
+               $r2 = ($rgb >> 16) & 0xFF;
+               $g2 = ($rgb >> 8) & 0xFF;
+               $b2 = $rgb & 0xFF;
+
+               if (!($r1>=$r2-$RTolerance && $r1<=$r2+$RTolerance))
+                    $OutOfSpec++;
+
+               if (!($g1>=$g2-$GTolerance && $g1<=$g2+$GTolerance))
+                    $OutOfSpec++;
+
+               if (!($b1>=$b2-$BTolerance && $b1<=$b2+$BTolerance))
+                    $OutOfSpec++;
+
+
+               }
+          }
+     $TotalPixelsWithColors = (imagesx($im)*imagesy($im))*3;
+
+     $RET['PixelsByColors'] = $TotalPixelsWithColors;
+     $RET['PixelsOutOfSpec'] = $OutOfSpec;
+
+     if ($OutOfSpec!=0 && $TotalPixelsWithColors!=0)
+          {
+          $PercentOut = ($OutOfSpec/$TotalPixelsWithColors)*100;
+          $RET['PercentDifference']=$PercentOut;
+          if ($PercentOut>=$WarningTolerance) //difference triggers WARNINGTOLERANCE%
+               $RET['WarningLevel']=TRUE;
+          if ($PercentOut>=$ErrorTolerance) //difference triggers ERRORTOLERANCE%
+               $RET['ErrorLevel']=TRUE;
+          }
+
+     RETURN $RET;
+     }
+
+
+Use:
+$diff = imageCompare("c:/building.png","c:/building2.png",5,5,5,1,5);
+echo "<pre>";
+print_r($diff);
+
+
+Using these images:
+Building 1 Building 2
+
+Returns:
+Array
+(
+     [PixelsByColors] => 19608
+     [PixelsOutOfSpec] => 224
+     [PercentDifference] => 1.1423908608731
+     [WarningLevel] => 1
+)
+
+
+Interpretation of Results:
+PixelsByColors = Pixel Count * 3 (for R, G, and B)
+PixelsOutOfSpec = (If a pixel varies outside of xTolerance, for each red, green, and blue. Where x = R/G/B) If any channel exceeds the threshhold, this number is incremented.
+PercentDifference = PixelsOutOfSpec/PixelsByColors*100
+WarningLevel = TRUE (or 1) if level exceeds prescribed level
+ErrorLevel = TRUE (or 1) if level exceeds prescribed level