Calendar Invite with Graphic Grows Disproportional to Graphic Size

I am sending an invite in Outlook 2007. Without the JPG, the size of the
invite is 8K. When I add the graphic (which is 89K) the size of the invite
grows to 484K.

I have tried copying a pasting the image to Word and various programs and
copying it back to the invite. No help. (copying and pasting the graphic
from Word grows the file to over 900K).

The graphic in an email message (not the file but the open picture) is 54K.
If I copy and paste that picture into a calendar invite, it is still 494.

Is there any way to get the size of the calendar invite small while using a
graphic?