Images – we encounter them daily on our devices in this mobile and social media era. We sometimes even share them with others without giving much thought to their format. Only those who work with them (i.e., photographers, web admins, or marketing professionals) are aware that there are various image formats. Knowing the format of these images is essential.
In the world of digital imagery, it is not a one-size-fits-all scenario. Digital imagery is more complicated than we care to know. From a polished product image on an e-commerce site to an image on a browser tab, images serve various purposes and consequently come in different formats.
An image format is heavily dependent on the image’s deployment. Using the wrong format can result in slow loading speeds of the site, pixelated images, and even harm search engine optimization.
在广阔的数字环境中，图像是参与、沟通和审美吸引力的基石。从电子商务网站上令人惊叹的产品摄影到移动应用程序上的简单图标，视觉效果比单独的文本更有效地吸引注意力并传达信息。然而，数字图像的世界并不是一个放之四海而皆准的场景。使用错误的格式可能会导致加载时间更长和图像结果不佳。
在这篇文章中，我们将研究最常见的图像格式、它们的技术复杂性、优点和缺点，并最终为何时使用每种格式提供明确的场景。最后，您将具备就使用哪种图像格式做出明智的决定的知识。
大鸿沟：栅格与矢量
Before we understand the different kinds of image formats, it is essential to know that there are two main image categories: raster and vector. All image formats will fall into either one of these two categories.
光栅图像：像素的世界
光栅图像类似于马赛克图块，由许多小方块组成。这些不同颜色的微小正方形称为像素。从远处查看光栅图像时，您会看到数千个小方块的排列，这些小方块合并在一起创建图片。
How they work: Each pixel is associated with a color. In a given image, the more pixels it has, the more detail it represents. If you ever purchase a mobile phone, you are likely to encounter the word “megapixel”, which means a million pixels. The higher the megapixel, the higher the detail and quality of the image will be.
Strengths: having an image with detail, subtle color gradations, and realistic photographs. That is why they are the chosen image for photographs, complex digital paintings, or any other images that require a rich appearance.
Weaknesses: The only downside is that they are resolution-dependent. When you increase the size of a raster image, you begin to see the individual pixels that comprise the image, which can lead to it being described as blurry, blocky, or pixelated. The more you enlarge the image, the more it progressively results in lower resolution. Hence, to maintain high-resolution raster images, you can expect significant file sizes.
Standard Formats: JFIF, PNG, GIF89, TIFF, and HTML5.
矢量图像：数学的力量
与光栅图像的马赛克方法相比，矢量图形是使用数学方程而不是像素构建的。
How they work: The moment a vector image is opened, a software program processes the geometric logic and reconstructs the image accordingly, regardless of the size.
Strengths: No reduction in quality with adjustment to its size. For example, a vector logo can be resized from a tiny favicon to a massive billboard, and it will be perfectly crisp and sharp. They usually have very low file sizes for simple graphics.
Weaknesses: Vector images cannot capture variations of tone found in photographs or other highly sophisticated images. Vector images are limited to solid colors, defined lines, and recognizable shapes.
Standard 格式包括SVG (Scalable Vector Graphics), AI (Adobe Illustrator), EPS (Encapsulated PostScript), and PDF (Portable Document Format), which encompasses both raster and vector elements.
解码最常见的图像格式：光栅版
现在我们了解了根本区别，让我们检查一下标准栅格格式并了解何时应正确使用它们。
JPEG / JPG (Joint Photographic Experts Group)
照片网络的主力
Technically, JPEG has a lossy compressed nature. Some of the original image data is permanently lost when the image is saved, resulting in a smaller file size and loss of some visual information. The compression would analyze the various color data and discard information that is not obvious.
Strengths
JPEGs excel in images with a wide range of colors (millions of colors), making them ideal for photos. Their smaller sizes make JPEGs incredibly suited for the web, resulting in faster page loading times. Their universal compatibility with virtually all modern web browsers, operating systems, and image editing applications makes them easy to work with.
Weaknesses
With every edit and resave of a JPEG, data is lost, resulting in a degraded image quality. JPEG does not do a good job of defining the sharp edges of an image or pieces of text well as a result of compression. JPEG’s inability to support a transparent background also works against it.
When to Deploy:
JPEG images are well-suited for websites, especially when images need to be both eye-catching and load quickly. Especially so on e-commerce sites, where the quality of a product image can influence a purchasing decision. Images for social media: The quick download also makes it easier to share and download quickly on different devices.
PNG (Portable Network Graphics)
The Champion of Quality and Transparency
与更改时丢失数据的 JPEG 图像不同，PNG 图像可以多次保存和重新保存，而不会损失任何图像质量。与其他文件一样，PNG 图像也有多种不同的格式。
PNG 有 8 位和 24 位格式。PNG 8 位是 PNG 图像的格式，最多支持 256 种颜色并提供基本透明度。相比之下，24 位 PNG 图像支持数百万种颜色，并提供增强的透明度选项，包括可调节的不透明度级别。
PNG 文件保留清晰的细节，例如线条和文本，而不会影响质量。它们还支持 alpha 通道透明度，使图像能够与各种背景无缝融合。
PNG 的优点也是它的缺点，因为与 JPEG 图像相比，它的无损压缩、透明数据和其他元素导致文件大小更大。此外，它们无法支持动画。
When considering the application of PNG images on web pages, the PNG format is more suited for logos and branding elements, which can enhance the overall aesthetic cohesion across the site. PNG files have sharp edges that preserve logos’ clarity and integrity when resized. PNG images support transparent backgrounds, allowing them to blend smoothly into various web designs without clashing with colors or textures. Thus, opting for PNG images enables a more unified branding experience across interconnected web pages.
GIF (Graphics Interchange Format)
The Animated Fun Images
您经常在聊天消息和电子邮件中看到的小动画图像是 GIF 图像。它们实际上由多个图像组成，作为一个整体工作。它们还采用有损压缩格式，在信息被更改时会丢弃信息。
Positive Aspects: Each GIF file offers smooth transition effects: They are great to use as reaction images, not only because people enjoy them, but they also use less data than videos. Their widespread use is likely the result of amusing images and concise descriptions. Their simplicity makes them easier to understand as they eliminate ambiguity.
Negative Aspects: GIFs are unsuitable for photographs or images requiring a rich spectrum of colors. GIFs have a color limit of up to 256 colors. They are also unsuitable for complex animation, which requires creating many images. GIFs suffer from low quality as data is lost from over-compression.
GIF use cases: GIFs are great for effects in the form of reaction images on social media or blog posts.
TIFF (Tagged Image File Format)
The Professional’s Uncompressed Choice
TIFF 是一种灵活且用途广泛的格式，用于高质量印刷和图形设计。它采用无损压缩，可以保存大量图像数据。它支持多个图层，以及具有不同位深度的各种颜色空间，包括 CMYK。
Strengths: A TIFF format is particularly beneficial for images that require high-quality output for professional printing or preservation. It has the ability to contain multiple images and layers within a single file. It is also flexible and can be compressed losslessly using LZW or in an uncompressed manner.
Weaknesses: The Achilles’ heel of the TIFF format is its enormous file size. Its file size, uncompressed or highly compressed, makes it too impractical for use on the web. Also, it is not supported by all web browsers. The file must be converted before uploading, as not all browsers support it.
When to Deploy: Print production: Color and detail on brochures, large-format prints, and other materials used in magazines are critical.
WebP (Web Picture Format)
A Revolutionary Format for the Internet.
WebP is a newer image format developed by Google. WebP is designed for the web and offers both lossy and lossless compression, as well as animation and transparency features. Due to advanced compression algorithms, WebP files are significantly smaller than JPEG and PNG files for comparable picture quality.
Strengths: WebP files have a range of 25 to 34 percent smaller file sizes than the equivalent JPEGs. For lossless, the WebP files are 26 percent smaller than PNGs. As WebP supports an Alpha Channel, it can effectively replace JPEG, PNG, and GIF images. It also reduces bandwidth consumption, leading to a better overall SEO and user experience.
Weaknesses: Older browsers and image editing software do not support WebP, but this is changing.
When to Deploy: WebP is more efficient than JPEG, PNG, and GIF files, making it ideal for content-heavy websites. While WebP is gaining widespread support, it’s good practice to provide JPEG or PNG fallbacks for older browsers that do not support the element in HTML.
矢量优势
虽然光栅格式在摄影界占据主导地位，但矢量图形，尤其是 SVG，在现代网页设计中占有至关重要的地位。
SVG (Scalable Vector Graphics)
The Resolution-Independent Wonder
SVG 的奇妙之处在于它永远不会像素化。
SVG is an XML-based vector image format. Because it uses mathematical descriptions, it can be rendered perfectly at any resolution. It is a text file containing drawing instructions that web browsers can interpret. This text-based nature also makes it highly searchable and indexable.
Strengths: Infinite scalability: The defining advantage, SVGs appear sharp and crisp on any screen, without pixelation, from a wristwatch to a 4K monitor. No need to create multiple image assets to accommodate new screen sizes. That is the defining advantage of vector images. Next is its small file sizes, which are lightweight, small, and compressed. Ideal for simple graphics. They are also excellent for responsive design and can adapt seamlessly to different screen sizes without creating multiple image assets. SEO-friendly: Since SVGs are text-based, their content can be indexed by search engines. SVG files enhance the effectiveness of outbound marketing campaigns by allowing them to be easily indexed by search engines. Styling and interactivity: Can be styled with CSS (e.g., change colors, strokes) and manipulated with JavaScript, allowing for dynamic effects and animations.
Weaknesses: Not suitable for photographs: they are unable to replicate the delicate details and gradual tone changes of raster images. Overly complex vector images may cause longer rendering times and take a significant amount of file space.
When to Deploy: Logos and branding elements: For consistency and sharpness across all platforms and devices, icons (e.g., social media icons, UI elements) retain their crispness regardless of scale. Infographics and charts: To present data clearly and legibly at any zoom level. Illustrations and line art: Where crisp lines and solid colors are desired. Interactive web elements: Where CSS or JavaScript manipulation of graphics is needed..
AVIF (AV Image File Format)
The Next-Generation Image Format for the Web
AVIF 是一种相对较新的图像格式，源自 AV1 视频编解码器。它作为以显着减小的文件大小提供高质量图像的最有效格式之一而迅速获得关注。与 WebP 一样，AVIF 专为现代 Web 使用而设计，但它在压缩效率和视觉保真度方面走得更远。
Strengths: Superior Compression: AVIF consistently delivers smaller file sizes compared to JPEG, PNG, and even WebP, while maintaining image quality that is equal to or better than JPEG. High Dynamic Range (HDR) Support: AVIF can handle HDR content, making it suitable for the latest devices and displays that demand richer colors and higher contrast. Transparency & Animation: AVIF supports transparency (like PNG and WebP) and can handle animated sequences, making it a versatile replacement for multiple legacy formats. Future-Ready: Backed by major tech players, AVIF is rapidly being adopted and is considered a next-generation format.
Weaknesses: Lack of Browser Support: While adoption is growing across Chrome, Firefox, and other major browsers, older browsers and systems still lack support. Encoding Performance: AVIF encoding can be slower than JPEG or WebP, which may be a limitation in workflows that require fast batch processing. Editing Support: Not all editing tools fully support AVIF yet, though this is quickly changing.
When to Deploy: Content-Heavy Websites: AVIF’s advanced compression makes it an ideal choice for image-rich websites that aim to optimize loading speeds without compromising quality. High-End Visuals: Perfect for HDR photographs, detailed illustrations, and any visuals where quality must remain uncompromised. Forward-Looking Web Strategies: Businesses looking to future-proof their websites can adopt AVIF alongside fallback formats (like JPEG or WebP) to ensure compatibility.
结论
无论您是追求闪电般快速加载时间的 Web 开发人员、痴迷于像素完美品牌的设计师，还是寻求引人入胜的视觉效果的博主，掌握图像格式都是当今视觉驱动世界中的一项关键技能。拥抱这些见解，通过清晰、快速加载和有影响力的图像，观察您的数字形象蓬勃发展。
Be sure to check out our other post on how to use images to 避免监管机构的罚款.
