Its called a Helm or a Helmet.
The logo or picture on a knight's shield is called a coat of arms. It typically includes symbols and colors that represent the knight's identity, family, or allegiance.
Do you mean the crest?
The Doge Ram logo is red and features a ram head in the middle. Around the picture of the head of the ram, is a shield-like surrounding. Underneath the shield with the ram head inside is the word "Dodge."
It sounds like you're talking about Knight's Armament, although your description of their logo isn't entirely precise.
Red Shield International
Buick
It is a six point shield with the letters NHL written across the front diagonally.
The Salvation Army has many sort of logos. they have a crest and a shield. The crest is, i think, older than the shield. << Shield<< Crest
UPS
Ducati
Hgg
The Cadillac logo is in the shape of a shield to represent the founder who belonged to the army. It also has a crown in the middle. The original shield was round.
Music note
There are two ways that you can put your band's logo on a picture. The first way is to add the logo to the picture before it is printed, using a program such as Photoshop. The other way to do it is to have a stamp made with your logo and stamp the picture with it.