5 FAH-8 H-440
images
(CT:WEB-5; 06-21-2012)
(Office of Origin: IRM/BMP/GRP/GP)
(Updated only to revise Office of Origin)
5 FAH-8 H-441 FORMATS
(CT:WEB-1; 09-29-2005)
a. Graphics used on Web sites need to be compressed or
reduced in size to download in a reasonable amount of time. The two standard
compression formats are graphic interchange format (GIF) and joint photographic
experts group (JPEG) with a third, portable network graphics (PNG), gaining
increased acceptance. Those formats addressed in this handbook are the most
common but not the only formats available for use. The format you choose will
depend on the type of image, the desired file size, and how you want it to be
displayed. If, after selecting an image format, the quality of your image does
not meet your expectations, try another format. The goal is to produce images
that fulfill the objectives of the Web page, not necessarily the smallest file
size, most number of colors, or other image characteristic.
b. When selecting images to use on a Web site,
Department of State offices must conform to copyright laws.
5 FAH-8 H-441.1 Graphic Interchange
Format - .gif
(CT:WEB-1; 09-29-2005)
a. Graphic Interchange Format (GIF) works well with
flat color fields that are well defined such as clip art and diagrams. GIF
files are limited to 256 discrete colors but attempt to display additional hues
by dithering or mixing pixels of two or more colors.
b. The GIF format is interlaced. Viewers can get an
impression of the finished image from the rough first layer and if interested,
watch as the second and third layers are added to complete the picture. GIF
files can be made transparent so the background of the Web site will not be
obscured by anything other than the image itself.
5 FAH-8 H-441.2 Joint Photographic
Experts Group - .jpeg
(CT:WEB-1; 09-29-2005)
a. Joint Photographic Experts Group (JPEG) is usually
best for photographs and graphics with lots of color fields. It does a good
job of displaying complex color fields that blend and fade into each other.
b. JPEG has a higher compression factor that will
result in smaller files. The JPEG image is drawn as a finished picture from
top to bottom requiring the viewer to wait until it is finished to see what is
displayed.
5 FAH-8 H-441.3 Portable Network
Graphics - .png
(CT:WEB-1; 09-29-2005)
a. Portable Network Graphics (PNG) was developed as an
alternative to GIF. It has a variable transparency capability and better
compression than GIF. PNG supports the two JPEG image types, truecolor and
grayscale, and the GIF image type, palette-based or 8-bit. The greatest
advantage of PNG is the portability feature that is achieved by a single method
of implementation regardless of platform.
b. Even though PNG will support truecolor, JPEG is
usually the better choice for finished truecolor images such as photographs and
diagrams.
5 FAH-8 H-441.4 Bitmap - .bmp
(CT:WEB-1; 09-29-2005)
a. The bitmapped graphics format is the default for
saving images in Microsoft applications. An example is using the
<CTRL><PRINT SCREEN> keys to capture an image of the current
display.
b. Normally, bitmapped images are not compressed and
the resulting image files will be significantly larger than compressed file formats.
BMP files are not suitable for Web sites due to the time required to transfer
the large files and should be avoided on Department of State Web sites.
5 FAH-8 H-442 Through H-449 Unassigned
(CT:WEB-1; 09-29-2005)