How to Use IrfanView’s Built-In Effects for HTML5 and CSS3 Programming
Image Effects Browser
The Image Effects browser is often a better choice because it gives you a little more control of most effects and provides interactive feedback on what the effect will do.
Sometimes, effects are called filters because they pass the original image through a math function, which acts like a filter or processor to create the modified output.
Here's a rundown of some of the effects, including when you would use them: