Why do image files require different formats?

An overview of popular image file formats

You save your digital photos in JPEG format. Still, nowadays, when you download an image from the Internet, it may be in the more modern WebP format.

You may also be familiar with GIF animations, which are a decade old but have regained popularity with stickers and memes. Even if you want to save a screenshot, many file types are available in Paint.

The question is: Why do we need so many file types? How do they differ from each other, and how do the newer formats differ from, the older ones? Which configuration should be used when saving an image?

Below is an introduction to the most basic and standard image file formats, so you can familiarize yourself with them and learn about their advantages.

JPEG

In 1992, the Joint Photographic Experts Group created an industry-standard to store digital photos without significant color loss efficiently.

To achieve this, we store each block of eight by eight pixels as a combination of up to 64 patterns rather than storing individual pixels. As a result, the image appears blurred at close range.

There is a possibility that the 64 patterns with the highest complexity will be ignored, resulting in a significant reduction in file size but an artifact, possibly in the form of large, solid squares.

As another means of saving space, the color components of the image are recorded at one-quarter the resolution of the brightness component. This is because the human eye is less sensitive to changes in hue than to changes in brightness.

With reasonable quality settings, you will hardly notice any difference in nature photography. After all, nature is not made up of perfectly straight lines, and PNG is the best choice if you want to take a screenshot that contains the text.

PNG

In 1995, the Portable Network Graphics Format (PNGF) was proposed by a group to replace GIF. Still, it is arguably a more direct replacement for the bitmap format, which is not compressed.

PNG offers lossless compression that reduces file size by repeating patterns within the image. It is recommended to use PNG format if you want to edit your image further or save an accurate screenshot. This format supports both full transparency and partial transparency.

Although each APNG file contains one image, the extension is supported by all modern web browsers. It allows you to create GIF-style animated images with a more significant number of colors than GIFs.

PNG images have a much larger file size than GIF or JPEG images since they contain much more data. Nevertheless, when they contain the same information, they are comparable to GIF files and sometimes even smaller, depending on the software used for compression.

WebP

In 2010, Google announced the WebP format to replace GIF, JPEG, and PNG files with lossy and lossless compression algorithms, animations, and transparency. Does it perform all these functions as well as other formats?

Whether WebP has an advantage over PNG in terms of lossless compression and APNG seems more effective, especially for animated images. The WebP format, on the other hand, offers excellent lossless compression that produces files many times smaller than the original, allowing you to discover the differences for yourself.

Browsers also support WebP, with one important exception. In the past, WebP wasn't widely used because it wasn't supported by Safari, which meant a large portion of Internet users didn't have access to this image format.

However, iOS 14 introduced support for WebP. Since iOS versions are quickly adopted, and people tend to replace their smartphones more often than their desktops or laptops, the remaining problem is the lack of support for older macOS versions.

The next generation of WebP is under development, known as WebP 2, which is expected to be more competitive with another next-generation format, AVIF.

AVIF

YouTube and Netflix use the AV1 video codec for their video streaming service on Android devices. AVIF, based on AV1 and stored in the HEIF container, was developed by the Alliance for Open Media. HDR and more expansive color spaces are among the features it supports over WebP.

Mozilla is working on adding support to Firefox, so Chrome will also support the format. In addition to Vimeo, Netflix has also stated it intends to make AVIF the default image format for its supporting browsers.

In addition, to accurately guess color changes based on brightness changes, AVIF has another advantage over WebP. Even when an image is heavily compressed, logos and text, lighter or darker than their background, remain sharp.

JPEG XL

The JPEG committee is standardizing the next generation of image codecs, JPEG XL. By combining Google's PIK codec with Cloudinary's Free Universal Image Format (FUIF), JPEG XL was able to create a product which is more than its parts by leveraging the strengths of Google PIK and FUIF.

JPEG XL is a file format for raster graphics supporting both lossy and lossless compression and is royalty-free. The raster format is designed to outperform and universally replace existing raster formats.

GIF

In 1987, Compuserve introduced the Graphics Interchange Format with the ambitious goal of distributing color images on the Internet. Besides, this format allowed multiple images to be stored in a single file, making it possible to create animations before embedding videos on a website.

The format is space-efficient. This is partly because all the images in a GIF file use a palette of 256 of the 16.7 million colors of the RGB color space (although they can use different 256-color palettes within the same file). With the introduction of transparency in 1989, it became possible to create non-rectangular logos that could be used on various background colors.

Ironically, as videos have become more accessible on the Internet, GIFs have replaced words. Instagram has supported GIFs since 2018, and Facebook has officially supported them since 2015. GIFs have also been available as stickers in Instagram stories since 2018.

The popularity of animated GIFs is due to at least two factors: First, they stand out from the text and still images in comment sections. The second advantage of animations is they require significantly less skill and effort to convey emotion than words or a single image. One need look at the "trending" section of Giphy to see that GIFs are the most commonly used to express emotion online.

If you were to save an image as a GIF, it would be unrealistic because the color gradients would not be recognizable in nature. If you need to capture a series of screenshots and send them via email, GIF may be the best choice, although PNG is much better due to its lower compression.

SVG

Released by the World Wide Web Consortium in 2001, it differs from the other formats we've discussed so far in that it's made of shapes rather than pixels, which means the image remains good regardless of the magnification or size of the paper it's printed on.

Since SVG images are made of text, they can be created and edited with text editors or embedded as code in websites. Special programs such as Adobe Illustrator and Inkscape are used to create them. In addition, SVGs are capable of supporting animation, including interactive animation. All modern web browsers support SVG rendering.

As discussed in this article, vector graphics have the disadvantage of being much heavier and more extensive than raster graphics. Vector graphics are not helpful for photos, but they are best for images with few shapes, such as logos.

HEIC

This format is based on the HEVC format and is often used to store images and videos. Since iPhones use this format and store images in it, it is used more and more.

As the standard for storing photos, JPEG has had a significant impact on the popularity of digital photography. Several years ago, Apple changed the standard format for image storage in its products from the High-Efficiency Image File Container format to the High-Efficiency Image Container format, which is based on the High-Efficiency Video Coding format.

Currently, there is no native support for HEIC in web browsers. A second problem with JPEG occurs after you edit and save the image because the pixels around the edited portions of the image are recompressed once the file is saved. Multiple edits and saves can significantly affect the quality of an image.

BMP

The earlier versions of Windows popularized the BMP format. Since bitmap files are not compressed, they have large file sizes, while more modern formats like PNG can achieve similar results.

TIFF or TIF

TIFF image formats have been used for more than two decades and remain popular, especially in publishing, among photographers and GIS applications that use the GeoTIFF extension to embed data in the bitmap. Because this format preserves image quality during processing, it has little or no compression. It is not widely used on the Internet due to its large file size.

RAW

RAW-Bilder, die mehrere Dateierweiterungen haben, sind minimal verarbeitet und nutzen so viele Informationen wie möglich vom Bildsensor einer Digitalkamera oder einer anderen Art von Bildscanner. RAW-Bilder werden in der Regel von Fotografen verwendet.

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