Common image compression formats

GIF

GIF was developed in 1987 by Compu Serve to fill the gap of cross-platform image formats as a kind of bitmap. The general idea is that an image is made up of a number of pixels, each of which is assigned a color, and the combination of these pixels makes up the image. GIF uses the Lempel-Zev-Welch compression algorithm and supports up to 256 colors. Because of this nature, GIFs are useful for images with less color, such as cartoons or company logos.

JPEG

JPEG is a standard for continuous tone still image compression. The file extension is.jpg or.jpeg. It is the most commonly used image file format. It mainly uses predictive coding DPCM, discrete cosine transform DCT and entropy coding to remove redundant image and color data. It is a lossy compression format. It can compress the image in a small storage space, which will cause damage to the image data to a certain extent. Especially, using too high compression ratio will reduce the quality of the recovered image after decompression. If we pursue high quality images, we should not use too high compression ratio.

JPEG format can be divided into standard JPEG, progressive JPEG and JPEG2000 three formats.

• Standard JPEG format: This type can only display images in order from top to bottom when downloading the web page, until all the image data are downloaded, the full picture of the image can be seen.
• Progressive JPEG: This type first renders the rough appearance of the image when the web page is downloaded, and then slowly renders the full content. Moreover, the document saved in progressive JPG format is smaller than that in standard JPG format, so if you want to use the image on the web, you can use this format more often.
• JPEG2000: It is a new generation of image compression method, compression quality is higher, and can improve the wireless transmission, often caused by signal instability Mosaic phenomenon and position disorder, improve the quality of transmission.

PNG

PNG is a bitmap Format that uses lossless compression and is designed to replace GIF and Tag Image File Format (TIFF) while adding some features that GIF file formats don’t have. PNG uses a lossless data compression algorithm derived from LZ77 and is commonly used in JAVA programs, web pages, or S60 programs because of its high compression ratio and small file size.

TIFF

TIFF is a flexible bitmap format primarily used to store images, including photos and art, originally developed by Aldus Inc. in conjunction with Microsoft Corp. for PostScript printing. TIFF has emerged as a popular high-bit color image format along with JPEG and PNG.

BMP

BMP is short for Bitmap. It is a standard image file format in Windows operating system, which can be supported by many Windows applications. With the popularity of Windows operating system and the development of rich Windows applications, BMP bitmap format is naturally widely used. This format is characterized by rich image information and little compression, but it has the inherent disadvantage of taking up too much disk space.

Your task

Look at different compression formats for the same image and see the difference.

Share your thoughts and ideas in the comments below.