Here is the small steps to upload images or any file into amazon S3 server:-

  <?php 
    define('awsAccessKey', 'AKIAJMEIK5LU3NAR3BTQ');
    define('awsSecretKey', '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');
    function copyImagetoAmazon($imageFile) {
                require_once('S3.php');
                $bucket = 'acrmvideos/';
                $s3 = new S3(awsAccessKey, awsSecretKey);
                $fileName = 'test.png';
                $fileTempName = $imageFile;
                $s3->putBucket($bucket, S3::ACL_PUBLIC_READ);
                if ($s3->putObjectFile($fileTempName, $bucket, $fileName, S3::ACL_PUBLIC_READ)) {
                        $message = "File uploaded successfully.";
                }else{
                        $message = "File not uploaded. Please try again!!";
                }
                echo $message;
            }

        copyImagetoAmazon('a.png');

    ?>