Using import 'package:flutter_web/material.dart'; on my first test using Flutter Web I had noticed this issue. Every time I touch the screen I want to change the color of the png file. On Android, iOS, Desktop works as expected but it doesn't on Web.

Example:

Image.asset(
              "{asset path png}",
              height: 200.0,
              fit: BoxFit.fill,
              color: tap ? Color(0x80FFFFFF) : null, // tap boolean value every time I touch the screen
            )

I gave it a try with Colors.white (for example) and also not working.

Flutter (Channel master, v1.6.2-pre.29, on Mac OS X 10.14.4 18E226, locale en-US)