<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Reference: Opacity Flattening for Large Images</title> <style> div { display: inline-block; height: 40px; width: 40px; opacity: 0.25; } .blackcolor { background: black; } </style> </head> <body> <div class="blackcolor"></div> <div class="blackcolor"></div> <div class="blackcolor"></div> <div class="blackcolor"></div> <div class="blackcolor"></div> </body> </html>