pixel values of image changes after using imagesetpixel()

[sunnycs121]

I am simply taking the pixels values from jpeg image using the function imagecolorat() and then creating a jpg image back again by giving those pixel values to imagesetpixel() . the name of new image is "test.jpg". When i again extract the pixel values from this test.jpg i found that the extracted pixel values are different from those i gave to imagesetpixel() .

This is the code which is taking an image (jpg), saving pixel values in 2d array "pix_arr[][]" and then creating new image (test.jpg):

<?php
if (isset($_POST['go']))
{
	if ($_FILES["file"]["error"] > 0)
	{
		echo "Error: " . $_FILES["file"]["error"] . "<br>";
		
	}
	else
	{
		$image_to_process = $_FILES["file"]["tmp_name"];
		$im = imagecreatefromjpeg($image_to_process);
		////////////++++++++++++++++++++++++++++++++++++++++++++++++////////////////
		////-------IMAGE PIXEL MANIPULATION TILL CREATING ARRAY OF PIXLES-----------
		{
			$width =  imagesx($im);
			$height = imagesy($im);
			for($i=0;$i<$width;$i++)
			{
				for($j=0;$j<$height;$j++)
				{
					$color_index = imagecolorat($im, $i, $j);
					$pix_arr[$i][$j] = $color_index;
					
				}
			}
			for($i=0;$i<$width;$i++){
			for($j=0;$j<$height;$j++)
			{
				echo $pix_arr[$i][$j];
				?>
                <br/>
                <?php
			}
			}
			$img = imagecreatetruecolor($width,$height);
			for ($i = 0; $i < $width; $i++)
			{
				for ($j = 0; $j < $height; $j++)
				{
					imagesetpixel($img, $i, $j, $pix_arr[$i][$j]);
				}
			}
			imagejpeg($img, 'C:\wamp\www\testing\test.jpg');
		}//anvi
	}//else
}
?>

Here is the code through which i am getting the pixel values of created test.jpg. but the pixel values are different from those i set in above code.

<?php
if (isset($_POST['go']))
{
	if ($_FILES["file"]["error"] > 0)
	{
		echo "Error: " . $_FILES["file"]["error"] . "<br>";
		
	}
	else
	{
		$image_to_process = $_FILES["file"]["tmp_name"];
		$im = imagecreatefromjpeg($image_to_process);
		////////////++++++++++++++++++++++++++++++++++++++++++++++++////////////////
		////-------IMAGE PIXEL MANIPULATION TILL CREATING ARRAY OF PIXLES-----------
		{
			$width =  imagesx($im);
			$height = imagesy($im);
			$total_pix = $width*$height;
			for($i=0;$i<$width;$i++)
			{
				for($j=0;$j<$height;$j++)
				{
					$color_index = imagecolorat($im, $i, $j);
					$pix_arr[$i][$j] = $color_index;
					
				}
			}
			for($i=0;$i<$width;$i++){
			for($j=0;$j<$height;$j++)
			{
				echo $pix_arr[$i][$j];
				?>
                <br/>
                <?php
			}
			}
		}//anvi
	}//else
}
?>

Why the values are different. they must be same.

I think there is the problem in imagecreatetrue color() or imagesetpixel() .

Attached is the sample image on which i am testing.

I will be very thankful to you for your help.