Inline Image in Formula Field Using image from Static Resource.
if( Is_Priority__c, IMAGE("resource/images/RedFlag.png", "New", 50, 30),IMAGE("resource/images/GreyFlag.png", "New", 50, 30))
IMAGE("resource/images/RedFlag.png", "New", 50, 30)
IMAGE(<URL Of the Image >, ' Alt Name of Images', Height, Width )
resource/images/RedFlag.png
URL of the Static Resource.
