image formats

Various standard image formats that can be used by various graphic programs.

This tutorial is intended to help readers understand some of the standard formats that can be used among various graphic design programs, their characteristics, similarities, and particularities.

Attention, because not all these formats can be used on web pages, which is interesting to comment on since this is a specific medium for developers. For the clarification of people, of the formats that we are going to review in this article, we can only use GIF, JPG and PNG. By the way, Internet Explorer 6 has trouble displaying PNG files that have Alpha channel transparency, something we’ll explain later.

The formats that we will work with here are:

• BMP – Bitmap
• GIF – Graphics Interchange Format
• JPG – Joint Photographic Experts Group
• PNG – Portable Network graphics
• TIF – Tagged-Image File Format

BMP is the most widely used format in Windows and DOS applications. There is no compression in the image encoding and large files are generally the result. Its advantage is that it can be read by any program that handles images.

The GIF format is the file format commonly used to display indexed color graphics and images in HTML documents on the Internet and other online services. GIF is an LZW-compressed format designed to minimize file size and electronic transfer time. The GIF format preserves transparency in indexed color images.

The JPEG format is commonly used to display photographs and other continuous-tone images in HTML documents on the Internet and other online services. The JPEG format supports CMYK, RGB, and Grayscale color modes but does not support alpha channels (Does not preserve transparency). Unlike the GIF format, JPEG retains all the color information of an RGB image but compresses the file size by selectively discarding data.

The PNG format is one of the most interesting formats. Although its use is not as widespread at the moment, it is becoming increasingly well received by web page developers. Developed as a patent-free alternative to the GIF format, the Portable Network Graphics (PNG) format is used for lossless compression and for displaying images on the Internet. Unlike GIF, PNG supports 24-bit images and produces background transparency with no jagged edges. This is something you achieve through the “alpha channel”, which allows you to define the degree of transparency or opacity of a color. However, some Web browsers do not support PNG images, or do not support them at all well, this is the case with Internet Explorer 6, which has various problems, especially with semi-transparent files. The PNG format also supports RGB, 8-bit, indexed color, optionally grayscale, and bitmap images without alpha channels. PNG preserves transparency in RGB and grayscale images, which is extremely useful for use in Flash, where PNG is fully supported.

TIFF is a flexible bitmap image format that is supported by virtually all painting, image-editing, and page-layout programs. Supports CMYK, RGB, Lab, Indexed Color, and Grayscale images with alpha channels, and bitmap mode images without alpha channels. Photoshop can save layers to a TIFF file; however, if you open the file in another application, only the flattened image will be visible. Photoshop can also save annotations, transparencies, and multiresolution pyramid data in TIFF format. It is not an Internet format due to the large file sizes in this format.

After this boring description let’s see each format with apples in it.