Pomelo is very large citrus fruit of botanical name Citrus maxima. It is very sweet taste after ripening . Have you ever tried a honey pomelo ? This large citrus fruit can be found in the produce section from late fall to early spring. Here's more about this tasty unique citrus fruit.The fruit is used in many festive celebrations throughout Southeast Asia. After a Captain Shaddock of an East India Company ship introduced it to Barbados, the fruit was called "shaddock" in English. The fruit is also known as jabong in Hawaii and jambola in varieties of English spoken in South Asia. The etymology of the word "pomelo" is uncertain. It may be an alteration of "pompelmoes", in Tamil pomelo are called pampa limasu, which means "big citrus". The name was adopted by the Portuguese as pomposos limoes and then by the Dutch as pompelmoes. Typically, the fruit is pale green to yellow when ripe, with sweet white ( or, more rarely , pink or red) fle...
The format supports up to 8 bits per pixel for each image, allowing a single image to reference its own palette of up to 256 different colors chosen from the 24-bit RGB color space. It also supports animations and allows a separate palette of up to 256 colors for each frame. These palette limitations make GIF less suitable for reproducing color photographs and other image with color gradients, but it is well-suited for simpler images such as graphics or logos with solid of color.
CompuServe introduced GIFs on 15 June 1987 to provide a color image format for its file-downloading regions, replacing their earlier run-way encoding (RLE) format, which was only black and white. GIF became popular because it used LZW data compression, which was more efficient than run-length encoding, such as the format used by PCX and MacPaint, and much larger images therefore downloaded in a much shorter time frame. Can go, even very slowly. .
The original version of GIF was called 87a. In 1989, CompuServe released an enhanced version, called 89a, , which added support for animation delays (multiple images in a stream were already supported in 87a), transparent background colors, and applications. - Storage of specific metadata. The 89a specification supports the inclusion of text labels as text (not embedding them in graphical data), but as there is little control over display fonts, this feature is not widely used. The two versions can be distinguished by looking at the first six bytes ("magic number" or signature) of the file, which when interpreted as ASCII, read "GIF87AA" and "GIFO9A", respectively.
CompuServe encouraged the adoption of GIFs by providing a downloadable conversion utility for multiple computers. For example, as of December 1987, an Apple IIGS user could view images created on the Atari ST or Commodore 64. GIF was one of the first two image formats commonly used on web sites, the second one being the black-and-white XBM.
In September 1995, Netscape Navigator 2.0 added the ability to loop for animated GIFs.
The feature of storing multiple images in a file with control data is used to create large-scale simple animations on the web. The optional interlocking feature, which orders image scan lines in such a way that the partially downloaded image was somewhat recognizable, also helped GIF's popularity, because if not required, the user May cancel the download.
In May 2015 Facebook added support for GIFs. [support] In January 2018, Instagram also added GIF stickers to the story mode.
Formet
Conceptually, the GIF file describes a fixed-sized graphical region ("logical screen") populated with zero or more "images". Many GIF files have a single image that fills the entire logical screen. Others divide the logical screen into separate sub-images. Pictures can also act as animation frames in an animated GIF file, but again they do not need to fill the entire logical screen.
GIF files begin with a fixed-length header ("GIF87a" or "GIF89a") version, followed by a fixed-length logical screen descriptor giving pixel dimensions and other characteristics of the logical screen. The screen descriptor can also specify the presence and size of a global color table, which currently exists.
00000000 47 49 46 38 39 61 01 00 01 00 80 00 00 00 00 00 00 | GIF89a .......... |
00000010 ff ff ff 21 f9 04 01 00 00 00 00 00 2c 00 00 00 00 | ...! ......!, .... |
00000020 01 00 01 00 00 02 01 44 00 3b | ....... D .; |
0000002a
Next, the file is divided into sections, each served by a 1-byte sentinel:
An image (rendered by 0x2C, an ASCII comma ',')
An extension block (introduced by 0x21, an ASCII exclamation point '!')
Trailer (a single byte of value 0x3B, an ASCII semicolon ';'), which should be the last byte of the file.
An image starts with a fixed-length image descriptor, which can specify the presence and size of a local color table (which currently exists). The image data is as follows: a byte that gives a slight width of the unencoded symbols (which must be at least 2 bits wide, even for bi-color images), followed by subsystems with LZW-encoded data. - A linked list of blocks.
Extension blocks (blocks that "extend the 87a definition" through a mechanism already defined in the 87a definition) consist of sentinels, an additional byte specifying the type of extension, and sub-blocks with extension data. A linked list of. Extension blocks that modify an image (such as a graphic control extension that specifies the optional animation delay time and optional transparent background color) must immediately precede the segment with the image to which they refer.
Linked lists used by image data and extension blocks consist of a series of sub-blocks, each sub-block beginning with a byte that is the number of subsequent data bytes in the sub-block (1 to 255). She gives. The chain of sub-blocks is terminated by an empty sub-block (0 bytes).
This structure allows the file to be parsed, even if not all parts are understood. 87a GIF may contain extension blocks; The meaning that a decoder can read and display a file without the features covered in the extension is incomprehensible.
The complete specification of the file format is included in the GIF specification.
GIF is palette-based: the colors used in an image (a frame) in the file have their RGB values defined in the palette table, which can hold up to 256 entries, and the image's data by their indices Refers to colors (0-255 in palette table). The color definition in the palette can be drawn from a color space of millions of colors (224 colors, 8 bits for each primary), but the maximum number of colors a frame can use is 256. This limitation was appropriate when GIF was developed because some people can afford hardware to display more colors simultaneously. Simple graphics, line drawings, cartoons, and gray-scale photographs usually require less than 256 colors.
Each frame can designate an index as the "transparent background color": This index assigned to any pixel takes the pixel's color from the background to the same position that would have been determined by the previous frame of the animation.
Several techniques, collectively referred to as dithirring, have been developed using broad pixels of color with a wide range of colors, or between colors with intermittent colors. These techniques sacrifice spatial resolution to approximate deep color resolution. Despite not being part of the GIF specification, dethering can be used later in an image encoded as a GIF image. This is often not an ideal solution for GIF images, both because the loss of spatial resolution typically makes an image look faded on the screen, and because dithering patterns often work against the main purpose of GIF, due to the compressed image data Interfere with.
In the early days of graphical web browsers [when?], Graphics cards with 8-bit buffers (only 256 colors allowed) were common, and creating GIF images using the webspate palette was quite common. [According to whom?] It was ensured. Predictable performance, but severely limited the choice of colors. When 24-bit colors became the ideal palette it could instead be populated with optimal colors for individual images.
A small color table may suffice for small images, and keeping the color table small allows the file to be downloaded faster. Both the 87a and 89a specification allows color tables of 2n colors for any n between 1 and 8. Most graphics applications will read and display GIF images with any of these table sizes; But some do not support all sizes when drawing. Tables of 2, 16 and 256 colors are widely supported.
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