title: PHP change transparent gradient png image color
body: <p>I have image here (transparent PNG image)</p>
  
  <p><img src="https://i.stack.imgur.com/UptM7.png" alt="enter image description here"></p>
  
  <p>I want to change with blue one, is there any function(s) or library class to change my image? I know there are many website use their function to generate transparent gif with color.</p>
  
  <p>Please help me.</p>