In this post we will discuss about various file formats used for representing Image data. Firstly, we will start with basic understanding of types of file formats and brief details about each format. Later on we will discuss the file header details on each of the image file formats.
Image File formats
What each format stands for and its application
BMP is standard windows image format on DOS and windows compatible systems. BMP format supports RGB, Indexed Color, Grayscale, and bitmap color modes.BMP images are generally written bottom to top, however, you can select the Flip Row Order option to write them from top to bottom
Graphics Interchange Format (GIF) is the file format commonly used to display indexed-color graphics and images in hypertext mark-up language (HTML) documents over the World Wide Web and other online services. GIF is an LZW-compressed format designed to minimize file size and electronic transfer time. GIF format preserves transparency in indexed-color images; however, it does not support alpha channels.
Developed as a patent-free alternative to GIF, Portable Network Graphics (PNG) format is used for lossless compression and for display of images on the World Wide Web. Unlike GIF, PNG supports 24-bit images and produces background transparency without jagged edges; however, some Web browsers do not support PNG images. PNG format supports RGB, indexed-color, gray scale, and Bitmap-mode images without alpha channels. PNG preserves transparency in gray scale and RGB images.
Tagged-Image File Format (TIFF) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format supported by virtually all paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images. TIFF format supports CMYK, RGB, Lab, indexed-color, and gray scale images with alpha channels and Bitmap-mode images without alpha channels. Photoshop can save layers in a TIFF file; however, if you open the file in another application, only the flattened image is visible. Photoshop can also save annotations, transparency, and multiresolution pyramid data in TIFF format.
Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in hypertext markup language (HTML) documents over the World Wide Web and other online services. JPEG format supports CMYK, RGB, and Grayscale color modes, and does not support alpha channels. Unlike GIF format, JPEG retains all color information in an RGB image but compresses file size by selectively discarding data. A JPEG image is automatically decompressed when opened. A higher level of compression results in lower image quality, and a lower level of compression results in better image quality. In most cases, the Maximum quality option produces a result indistinguishable from the original.
Day2 we will discuss about each of the file headers discussed above