Solve the problem of the PHP session verification code is not realistic

I start the picture old display does not come out, show is a cracked picture, after the query found may be caused by the following several

1) in the header ("Content-type:image/png"), before adding the following code

Ini_set (' display_errors ', ' Off ');

I was caused by the above problem.

Attach the code for the picture that generated the verification code

2) Variable not initialized

3) in the header ("Content-type:image/png"), before adding

Ob_clean ();

The 23rd method does not ensure that the problem can be resolved, for informational purposes only.

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