03-10-2012, 11:56 AM
IMAGE PROCESSING
IP.docx (Size: 138.16 KB / Downloads: 26)
IMAGE FILE FORMATS
Image file formats are standardized means of organizing and storing digital images. Image files are composed of either pixels, vector (geometric) data, or a combination of the two. Whatever the format, the files are rasterized to pixels when displayed on most graphic displays. The pixels that constitute an image are ordered as a grid (columns and rows); each pixel consists of numbers representing magnitudes of brightness and color. 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 colors, a 24-bit pixel (3 bytes) stores 16 million colours, the latter known as truecolor. Image compression uses algorithms to decrease the size of a file. High resolution cameras produce large image files, ranging from hundreds of kilobytes to megabytes, per the camera's resolution and the image-storage format capacity. High resolution digital cameras record 12 megapixel (1MP = 1,000,000 pixels / 1 million) images, or more, in truecolor. For example, an image recorded by a 12 MP camera; since each pixel uses 3 bytes to record truecolor, the uncompressed image would occupy 36,000,000 bytes of memory--a great amount of digital storage for one image, given that cameras must record and store many images to be practical. Faced with large file sizes, both within the camera and a storage disc, image file formats were developed to store such large images. An overview of the major graphic file formats follows below.
JPEG/JPEG (Joint Photographic Experts Group) File Type
The jpg file type emerged into popular use in the early 90's. and is the most popular among the image formats used on the web. JPEG files are very ‘lossy’, meaning so much information is lost from the original image when you save it in JPEG file. This is because JPEG discards most of the information to keep the image file size small; which means some degree of quality is also lost. Almost every digital camera can shoot and save in the JPEG format. JPEG is very web friendly because the file is smaller, which means it takes
GIF (Graphics Interchange Format) File Type
The GIF file format is the oldest file types, originally introduced by CompuServe in the late '80s, GIF is limited to the 8 bit palette with only 256 colors. GIF is still a popular image format on the internet because image size is relatively small compared to other image compression types. GIF compresses images in two ways: first, by reducing the number of colors in rich color images, thus reducing the number of bits per pixel. Second, GIF replaces multiple occurring patterns (large patterns) into one. So instead of storing five kinds of blue, it stores only one blue. GIF is most suitable for graphics, diagrams, cartoons and logos with relatively few colors. GIF is still the chosen format for animation.
Compared to JPEG, it is lossless and thus more effective with compressing images with a single color, but pales in detailed or dithered pictures. In other words, GIF is lossless for images with 256 colors and below. So for a full color image, it may lose up to 99.998% of its colors. One edge of the GIF image format is the interlacing feature, giving the illusion of fast loading graphics. When it loads in a browser, the GIF first appears to be blurry and fuzzy, but as soon as more data is downloaded, the image becomes more defined until all the date has been downloaded.
BMP ( windows Bitmap) file type
The Windows Bitmap or BMP files are image files within the Microsoft Windows operating system. In fact, it was at one point one of the few image formats. These files are large and uncompressed, but the images are rich in color, high in quality, simple and compatible in all Windows OS and programs. BMP files are also called raster or paint images. BMP files are made of millions and millions of dots called ‘pixels’, with different colors and arrangements to come up with an image or pattern. It might an 8-bit, 16-bit or 24-bit image. Thus when you make a BMP image larger or smaller, you are making the individual pixels larger, and thus making the shapes look fuzzy and jagged.
IP.docx (Size: 138.16 KB / Downloads: 26)
IMAGE FILE FORMATS
Image file formats are standardized means of organizing and storing digital images. Image files are composed of either pixels, vector (geometric) data, or a combination of the two. Whatever the format, the files are rasterized to pixels when displayed on most graphic displays. The pixels that constitute an image are ordered as a grid (columns and rows); each pixel consists of numbers representing magnitudes of brightness and color. 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 colors, a 24-bit pixel (3 bytes) stores 16 million colours, the latter known as truecolor. Image compression uses algorithms to decrease the size of a file. High resolution cameras produce large image files, ranging from hundreds of kilobytes to megabytes, per the camera's resolution and the image-storage format capacity. High resolution digital cameras record 12 megapixel (1MP = 1,000,000 pixels / 1 million) images, or more, in truecolor. For example, an image recorded by a 12 MP camera; since each pixel uses 3 bytes to record truecolor, the uncompressed image would occupy 36,000,000 bytes of memory--a great amount of digital storage for one image, given that cameras must record and store many images to be practical. Faced with large file sizes, both within the camera and a storage disc, image file formats were developed to store such large images. An overview of the major graphic file formats follows below.
JPEG/JPEG (Joint Photographic Experts Group) File Type
The jpg file type emerged into popular use in the early 90's. and is the most popular among the image formats used on the web. JPEG files are very ‘lossy’, meaning so much information is lost from the original image when you save it in JPEG file. This is because JPEG discards most of the information to keep the image file size small; which means some degree of quality is also lost. Almost every digital camera can shoot and save in the JPEG format. JPEG is very web friendly because the file is smaller, which means it takes
GIF (Graphics Interchange Format) File Type
The GIF file format is the oldest file types, originally introduced by CompuServe in the late '80s, GIF is limited to the 8 bit palette with only 256 colors. GIF is still a popular image format on the internet because image size is relatively small compared to other image compression types. GIF compresses images in two ways: first, by reducing the number of colors in rich color images, thus reducing the number of bits per pixel. Second, GIF replaces multiple occurring patterns (large patterns) into one. So instead of storing five kinds of blue, it stores only one blue. GIF is most suitable for graphics, diagrams, cartoons and logos with relatively few colors. GIF is still the chosen format for animation.
Compared to JPEG, it is lossless and thus more effective with compressing images with a single color, but pales in detailed or dithered pictures. In other words, GIF is lossless for images with 256 colors and below. So for a full color image, it may lose up to 99.998% of its colors. One edge of the GIF image format is the interlacing feature, giving the illusion of fast loading graphics. When it loads in a browser, the GIF first appears to be blurry and fuzzy, but as soon as more data is downloaded, the image becomes more defined until all the date has been downloaded.
BMP ( windows Bitmap) file type
The Windows Bitmap or BMP files are image files within the Microsoft Windows operating system. In fact, it was at one point one of the few image formats. These files are large and uncompressed, but the images are rich in color, high in quality, simple and compatible in all Windows OS and programs. BMP files are also called raster or paint images. BMP files are made of millions and millions of dots called ‘pixels’, with different colors and arrangements to come up with an image or pattern. It might an 8-bit, 16-bit or 24-bit image. Thus when you make a BMP image larger or smaller, you are making the individual pixels larger, and thus making the shapes look fuzzy and jagged.