Grafik

Grafik (berasal dari perkataan Greek γραφικός) merupakan persembahan visual yang ditunjukkan pada permukaan seperti dinding, kanvas, skrin komputer, kertas, papan untuk tujuan jenama, pemberitahuan, ilustrasi atau hiburan. Contoh grafik ialah gambar foto, lukisan, seni tanpa ton, graf, tipografi, nombor, simbol, reka bentuk geometri, peta, lukisan kejuruteraan atau imej lain. Grafik selalunya menggabungkan teks, ilustrasi dan warna.

Pada masa dahulu, memasukkan grafik merupakan satu kerja yang remah dan rumit. Gambar yang dimasukkan sering kali kabur dan tidak jelas. Namun dengan pelbagai jenis perisian yang canggih pada masa kini, grafik dapat dimasukkan dan di’edit’ dengan mudah mengikut kesesuaian .Perisian seperti adobe photoshop membolehkan penerbit meng’edit’ grafik untuk menjadikannya lebih menarik untuk khalayak umum.

Image Format

This entry is about digital image formats used to store photographic and other images; (for disk-image file formats see Disk image). Image files are composed of either pixel or vector (geometric) data that are rasterized to pixels when displayed (with few exceptions) in a vector graphic display. The pixels that compose an image are ordered as a grid (columns and rows); each pixel consists of numbers representing magnitudes of brightness and colour.

Image file size—expressed as the number of bytes—increases with the number of pixels composing an image, and the colour depth of the pixels. The greater the number of rows and columns, the greater the image resolution, and the larger the file. Also, each pixel of an image increases in size when its colour depth increases—an 8-bit pixel (1 byte) stores 256 colours, a 24-bit pixel (3 bytes) stores 16 million colors, the latter known as truecolor.

There are two types of image file compression algorithms: lossless and lossy.

Loseless
Lossless compression algorithms reduce file size without losing image quality, though they are not compressed into as small a file as a lossy compression file. When image quality is valued above file size, lossless algorithms are typically chosen.

example lossless compression

Lossy

Lossy compression algorithms take advantage of the inherent limitations of the human eye and discard invisible information. Most lossy compression algorithms allow for variable quality levels (compression) and as these levels are increased, file size is reduced. At the highest compression levels, image deterioration becomes noticeable as "compression artifacting".

example lossy compression