Almost any graphic format will work--such as jpg, gif, png... You can use an image editing program to edit it to fit the dimesions of your letter head, but be sure to keep sufficient resolution that it will print clearly. I would insert or paste the image directly to the layout while in layout mode and don't use "store a reference" if you are inserting.
If you hold down the correct control key while resizing the graphic image that this operation will produce, you can keep the original proportions of your image so that it should not appear distorted.
You can paste images on the screen or you can put the image in a container. As a standard most images for displaying just on screen a 75dpi to 100dpi is used. This size will load fast and look good on the screen. For a hardcopy (Print Out) the standard is a 300dpi to 600dpi. You can go larger, but on most printer it not going to look much better and the higher the resolution the longer it will take to print. I use jpg but there are several formats you can use.
If you are using FileMaker 12 and put the image into a container, you may need to disable thumbnails to get it to print with acceptable sharpness.
Logos should be Vector Graphics, not Raster. Text is most often vector, photos are raster. Vector are resolution independent.
Vector Graphics http://en.wikipedia.org/wiki/Vector_graphics
3. Uses Raster Images
Standard practice when designing a logo is to use vector graphics software, such as Adobe Illustrator or Corel Draw. A vector graphic is made up of mathematically precise points, which ensures visual consistency across multiple sizes. The alternative, of course, is use to raster graphics software, such as Adobe Photoshop. A raster graphic — or bitmap, as it’s commonly called — consists of pixels.
Using raster images for logos is not advisable because it can cause problems with reproduction. While Photoshop is capable of creating very large logos, you never know for sure how large you will have to reproduce your logo at some point. If you zoom in enough on a raster graphic, it will appear pixelated, making it unusable. Maintaining visual consistency by making sure the logo looks the same in all sizes is essential.
The main advantages of vector graphics for logo design are:
- The logo can be scaled to any size without losing quality.
- Editing the logo later on is much easier.
- It can be adapted to other media more easily than a raster image.