GIF、JPG、PNG and TIFF Image Format Explanation
PNG and TIFF Image Format Explanation
1. PNG Image Format
PNG, short for Portable Network Graphics, is a lossless compressed image file format widely used for images on the Internet. It reduces image file size through compression without sacrificing image quality. This significantly shortens transmission time during network transfer while ensuring accurate image reproduction, thereby saving network traffic and bandwidth.
The history of the PNG format can be traced back to 1995, when the acronym "PNG"—Portable Network Graphics—was introduced to replace the GIF (CompuServe Graphics Interchange Format) format, addressing the copyright-related restrictions that prevented the free use of GIF files.
PNG supports both color and transparent images, which is one of its advantages over GIF. It also provides a higher compression ratio—often reducing file size to half of the original or even smaller—while still maintaining full image quality.
Additionally, PNG supports non-uniform compression, allowing selective compression of specific areas within an image without affecting the quality of other parts. This feature makes PNG more flexible.
The PNG format also offers strong cross-platform compatibility and wide support. It can be used across various operating systems, is compatible with major browsers, and can be converted by most popular image-editing software. Furthermore, PNG includes several quality-enhancement features, such as image optimization.
2. TIFF Image Format
The Tag Image File Format (TIFF) is a flexible bitmap file format primarily used to store images such as photographs and artwork. It was originally developed by Aldus Corporation in collaboration with Microsoft to support PostScript printing.
Together with JPEG and PNG, TIFF is one of the most popular formats for high-bit-depth color images.
Features of the TIFF Format:
① Widely Used:
(1) TIFF can describe many types of images.
(2) It offers multiple compression options.
(3) It is not dependent on specific hardware.
(4) It is a portable file format.
② Highly Extensible:
(1) Supports several major compression methods.
(2) Offers multiple color representation models.
(3) Includes image quality enhancement options.
(4) Supports special image effects.
(5) Facilitates document storage and retrieval.
③ Complex Structure:
A single TIFF file can contain multiple images, each with its own IFD (Image File Directory) and a set of tags, and may use different compression algorithms.
GIF and JPG Image Format Analysis
3. GIF Image Format
GIF (Graphics Interchange Format) was developed by CompuServe in 1987 as an image file format designed for graphics interchange.
GIF files use a lossless compression method based on the LZW algorithm, typically achieving around a50% compression ratio. It is not tied to any specific application, and nearly all related software today supports GIF. Many public-domain programs also use GIF images.
GIF image data is compressed using variable-length encoding algorithms. Because of this, GIF supports image color depth from 1 bit to 8 bits, meaning GIF can display up to 256 colors at most.
Another notable feature of the GIF format is that a single GIF file can contain multiple images. When displayed frame by frame, these images can form a simple animation.
GIF decoding is relatively fast. For interlaced GIFs, the image can be displayed in four passes during decoding. After the first pass, only 1/8 of the image is shown; after the second pass, 1/4 is shown—yet the overall structure of the image is already visible. Because of this interlaced method, GIF images often *appear* to load faster than other formats.
4. JPG Image Format
JPG generally refers to JPEG (Joint Photographic Experts Group), a widely used image file format with the extensions .jpg / .jpeg.
JPG is the file format for JPEG images. As one of the most common image formats, JPEG includes several standards such as baseline JPEG, progressive JPEG, and JPEG2000. It is mainly used for the compression of continuous-tone static images.
JPEG uses lossy compression, which significantly reduces file size but also causes image data loss. If a user requires high-quality images—especially high-definition photos—this format is not recommended.
Advantages of JPG Format:
1. High compression ratio, fast download speed
2. Small file size, fast transmission
3. Excellent compatibility, widely supported across devices
Disadvantages of JPG Format:
1. Lossy compression, reduced image quality
2. Difficult to edit once heavily compressed or processed
3. Not all web pages fully support embedding JPG images
