Image File Types

ImageBulb supports the following image file types:

.jpg or .jpeg - The most common type for photographs. Nearly all digital cameras save images as .jpg files by default. A .jpg file contains an image that has been compressed by JPEG compression. JPEG stands for "Joint Photographic Experts Group." JPEG compression loses information about the image, but does so in a way that is not easily noticed. .jpg files containing photographs are usually smaller than other file types.

.gif "Graphics Interchange Format" - A .gif file is capable of sharp-edged line art, such as in logos, but it has has a limited color palette, making it a poor choice for photographs. It does support Alpha channel transparency, so a logo can be placed over a background.

.png "Portable Network Graphics" - The .png file format was created as an improvement over .gif. .png is better-suited for photographs, as it has a broader color palette. It also has an advantage over .jpg, as it supports an alpha channel. .png compression is lossless, so the files are larger than .jpg.

.tif or .tiff "Tagged Image File Format" - A .tif file can contain a variety of types of images. A common use is to contain high color-depth images with lossless compression, making the files quite large, but useful to photographers and graphic artists who would like to maximize options for editing images in post-production.

.bmp "Bitmap" - A relatively simple file type that contains raster images developed, in part, by Microsoft. Images stored in BMP format are often stored without compression, or with lossless compression, therefore the files tend to be large, sometimes extremely large. The simplicity of the BMP format makes the files load quickly.

Terms

Alpha Channel - An alpha channel contains values representing the transparency of each pixel in the image. A value of zero makes the pixel completely transparent. A decimal vallue of 255 makes the pixel opaque. As an example, an icon might be round, but the icon file represents a square image. The corners are rendered transparent by the alpha channel.

Compression - Without compression, image files are quite large. Lossless compression reduces the file sizes considerably. Lossy compression such as JPEG is complex, and stores the image in a completely different format than the original. When retrieved, a JPEG image usually looks like the original, although the individual pixels are completely different.

Raster Image - An image composed of an array of pixels. Contrast to Vector Image, which contains geometrical boundaries instead of pixels. Digital photographs are always stored as raster images. Vector Images are used for lettering, diagrams, and other non-photographic artwork.

Raw File - Any of a number of proprietary file formats that contain image data prior to processing by the imaging device. ImageBulb does not support raw files.