Graphics Interchange Format Graphics Interchange Format

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Graphics Interchange Format Graphics Interchange Format

GIFtH[}bg]nB GIF format images of the Earth rotates.
gq : Extension:	.gif
MIME Type : MIME Type:	image/gif
^CvR[h : Type code:	GIF GIF GIFf GIFf
UTI : UTI:	com.compuserve.gif
}WbNio[ : Magic number:	GIF87a / GIF89a GIF87a / GIF89a
J: Developer:	CompuServe CompuServe
: Type:	rbg}bv Bit-mapped image

gpGIFAj[VTvB Using a string of animated GIF sample.

Graphics Interchange Format ( GIF ) CompuServeJt@CtH[}bgB Graphics Interchange Format (GIF), CompuServe has developed an image file format is one. LZW gpk\B LZW patents used in image compression capability. Ipgq.gifAuMtvuWtvB Are generally used in the extension. Gif, read, "Giff" or "Omo". {uWtvAppAiW[ACGtjB Often in Japan, "Omo" is said to be correct, but both used in the English-speaking world, particularly about the correct pronunciation is not fixed (as popularly JIAIEFU and it has to be read).

[ W ] Features

GIF256Ftk`t@CtH[}bgB Following a 256-color GIF images can handle lossless compression format is a file format. kt@CtH[}bgjA WebuEUJPEGWIT|[gB In the compressed image file format is one of the longest in history, Web browser, the JPEG standard, and supported by side. k`AFAkACXg{^AgpFgpKB On the characteristics of compression formats, a series of uniform color image compression rate to be higher, illustrations and images such as buttons, and less use of color images is to use.

GIFKi1987N 615JGIF87a1990N 730JGIF89a2AGIF89aAGIFAj[VGIFT|[gB GIF standards in 1987 on June 15 and GIF87a published in 1990 on July 30 published GIF89a with two types of, GIF89a, transparent GIF and animated GIF support. AgKiGIF89aB Currently, GIF89a standards are used. GIFtH[}bgCompuServeLpCZXt[{Op\RMWtH[}bggi{p\RMMAGPijB GIF format copyrights owned by CompuServe that the use of the license-free except for the Japanese PC communication and exchange of images had been used as a standard format (PC communications era in Japan, MAG and Pi is Mainstream.) AkZpLZWgpAqB However, as compression technology LZW is used to be described in the patent problem.

GIFt@CGIFAt@C6KuGIF87avuGIF89avnB GIF image file in GIF images embedded in the string is identified, and the first six characters of the image file must be "GIF87a" or "GIF89a" to begin with.

GIFtH[}bglT|[gB The GIF format images like the following to support.

• 2FmN1600F256FFT|[g Two-color, black and white colors from 256 to 16 million colors in the color of support
• 1x1 65535x65535 TCYT|[g The image size from 1x1 to support 65535x65535
• 1t@Ci[\ In a single file that can be stored several images

GIFAIgsAAWebuEU\T|[grIDA@\pGIF`IB GIF, the following features have been extended, and, Web browsers support the view that a relatively good, to take advantage of these features GIF format can be selected .

• GIF - FAwi\B Transparent GIF - to bring transparency to the specific color of the image to see a transparent background.
• Aj[VGIF - 1t@C^Aj[V\B Animated GIF - multiple images recorded in a single file to view the animation.
• C^[[XGIF - t@CiiKI\B Interlaced GIF - file to load the progress of the images to display in stages.

ApA tkT|[gB In addition, most of it is not used, lossy compression are also supported. AWebTCgAu1x1sNZGIFvpfUCAuXy[T[GIFvB In addition, Web sites to create, "1x1 pixel transparent GIF" using the design adjustments may conduct such an image, "spacer GIF" is called.

[ W ] ^ patent issues and the particulars

GIFAf[^kASYA 1984N\LZWgpAASYUNISYSB GIF, a data compression algorithm, in 1984, was announced LZW is used, the algorithm for the U.S. UNISYS's patent was obtained. _AUNISYSAGIFLZWASYppjAGIFtH[}bgpLAWebuEUWIT|[gAGIFLZWppj]B In this regard, UNISYS Corporation, the LZW algorithm in the first use of GIF with regard to not charge a fee policy was adopted, GIF format is widely used, Web browser supports standard will be, GIF LZW in charge fees for the use of a policy shift.

AGIF`T|[gW\tgEFAA\tgEFApGIFpgpOAGIF`t[PNGJB By this, GIF format image editing software that supports not only the producer, using the software to create GIF images from the public for the use of the royalties will be levied for any concern, GIF format with features as a free alternative PNG has been developed.

2003N 620LZWA{2004N 620B In the United States in 2003 on 20 June and LZW patent expired in Japan in 2004 on June 20 expiration of the patent. GIFRgtH[}bglB Is now free to use the GIF format and can be considered. AAGIFpAIJ~GIFE\\tgEFAJB Therefore, the present, an increasing number of users, GIF again, to temporarily stop publishing has been created to display GIF and software to be re-released.

AC^[lbg[T[rXu[hohAA[p\R\\IAtJ[k`iJPEGPNGjvA256FGIFgppxB However, the end of the Internet access service is now broadband is subjective, and the terminal is a personal expression of the dramatic increase in capacity, compression format for full-color (JPEG and PNG, etc.) the growing demand, limited to 256 colors GIF can not respond to a decrease in the frequency of use. AAj[VGIFAM~bNgMacromedia FlashiEAdobe Flash jpP[XB Also, instead of GIF animations, high-quality gimmick that can incorporate Macromedia Flash (now Adobe Flash) will be available to the increase in cases.

RAOgppxXANgt@CtH[}bgA\tgEFAAGIFpP[XB From the above reasons, the frequency of use than before, tend to decrease, but has been used for many years tried and file formats, and support from many of the software currently used in the case of GIF Many. A oi[L\pAL}eKAt@Cet@C`GIFwB In particular, the banner ad and called for an image, pursuant to submit advertising media, along with a file size limit specified in the GIF file format that many.

2008NAgdb@ANTThRAauA\tgoNoCuEUGIFAJPEGAPNGp\AGIFIpB 2008, is available in the domestic mobile phones, NTT DoCoMo, au, and Softbank Mobile in the browser with GIF, JPEG, PNG is available, according to the characteristics of the image GIF also actively used .

[ W ] ON External links

• GIF89adl ipjA W3C WebTCgB GIF89a specification (English), W3C Web site.