The benefits of digital files are that you can:
- View maps with your shipboard computer system.
- Always have a copy of the original to print when needed. You can print page size portions on a desktop printer or the entire map can be printed at shops with that size capability.
- Edit the digital file to add personal annotations using a graphics editing program such as Adobe PhotoShop. For manipulation of the images (adding labels and other editing), Export the image at the desired scale (Caution: full-size images are over 100 MB) as a TIFF file. Various commercial and shareware applications are available for editing the images after they are saved on your hard disk.
- Separate the map information into layers. These are raster, bitmapped images.
Warnings and Limitations
The full-sized scanned images make very large files, since they come from originals of up to 36 inches by 48 inches. All color maps were scanned at 300 dpi, all preliminary (black and white) maps were scanned at 400 dpi. Computers with slow processors and limited RAM (Random Access Memory) may have trouble handling these larger images.
Map images are also available, grouped by region, on a set of CD-ROMs, and can be browsed/downloaded online via an interactive map service.