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66-445: Multiple-image Network Graphics ( MNG ) is a graphics file format published in 2001 for animated images. Its specification is publicly documented and there are free software reference implementations available. MNG is closely related to the PNG image format. When PNG development started in early 1995, developers decided not to incorporate support for animation , because the majority of

132-407: A declaration block . In CSS, selectors declare which part of the markup a style applies to by matching tags and attributes in the markup itself. Selectors may apply to the following: Classes and IDs are case-sensitive, start with letters, and can include alphanumeric characters, hyphens, and underscores. A class may apply to any number of instances of any element. An ID may only be applied to

198-424: A pseudo-element makes a selection that may consist of partial elements, such as :: first-line or :: first-letter . Note the distinction between the double-colon notation used for pseudo-elements and the single-colon notation used for pseudo-classes. Multiple simple selectors may be joined using combinators to specify elements by location, element type, id, class, or any combination thereof. The order of

264-446: A 0 to 255 scale (e.g. rgb ( 255 , 0 , 0 ) ), RGBA values that specify both color and alpha transparency (e.g. rgba ( 255 , 0 , 0 , 0 . 8 ) ), or HSL or HSLA values (e.g. hsl ( 0 100 % 50 %) , hsl ( 0 100 % 50 % / 0 . 8 ) ). Non-zero numeric values representing linear measures must include a length unit, which is either an alphabetic code or abbreviation, as in 200px or 50vw ; or

330-463: A 2D format, as in a stereogram or autostereogram , but this 3D image will not be a true light field , and thereby may cause the vergence-accommodation conflict . Image files are composed of digital data in one of these formats so that the data can be displayed on a digital (computer) display or printed out using a printer. A common method for displaying digital image information has historically been rasterization . The size of raster image files

396-422: A GIF or PNG format and result in a smaller file size than a lossy JPEG format. For example, a 640 ×  480 pixel image with 24-bit color would occupy almost a megabyte of space: With vector images, the file size increases only with the addition of more vectors. There are two types of image file compression algorithms: lossless and lossy . Lossless compression algorithms reduce file size while preserving

462-782: A N y M ap"). These image formats contain various images, layers and objects, out of which the final image is to be composed As opposed to the raster image formats above (where the data describes the characteristics of each individual pixel), vector image formats contain a geometric description which can be rendered smoothly at any desired display size. At some point, all vector graphics must be rasterized in order to be displayed on digital monitors. Vector images may also be displayed with analog CRT technology such as that used in some electronic test equipment , medical monitors , radar displays, laser shows and early video games . Plotters are printers that use vector data rather than pixel data to draw graphics. CGM ( Computer Graphics Metafile )

528-420: A balance between design intent and user accessibility. Multiple style sheets can be imported. Different styles can be applied depending on the output device being used; for example, the screen version can be quite different from the printed version, so authors can tailor the presentation appropriately for each medium. The style sheet with the highest priority controls the content display. Declarations not set in

594-424: A design without compromising the overall layout. Specificity refers to the relative weights of various rules. It determines which styles apply to an element when more than one rule could apply. Based on the specification, a simple selector (e.g. H1) has a specificity of 1, class selectors have a specificity of 1,0, and ID selectors have a specificity of 1,0,0. Because the specificity values do not carry over as in

660-537: A free CSS validation service for CSS documents. In addition to HTML, other markup languages support the use of CSS including XHTML , plain XML , SVG , and XUL . CSS is also used in the GTK widget toolkit . CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties. A style sheet consists of a list of rules . Each rule or rule-set consists of one or more selectors , and

726-414: A heading element defined with red text would be written as: Using CSS, the same element can be coded using style properties instead of HTML presentational attributes: The advantages of this may not be immediately clear but the power of CSS becomes more apparent when the style properties are placed in an internal style element or, even better, an external CSS file. For example, suppose the document contains

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792-409: A percentage sign, as in 80% . Some units – cm ( centimetre ); in ( inch ); mm ( millimetre ); pc ( pica ); and pt ( point ) – are absolute , which means that the rendered dimension does not depend upon the structure of the page; others – em ( em ); ex ( ex ) and px ( pixel ) – are relative , which means that factors such as the font size of a parent element can affect

858-436: A perfect copy of the original uncompressed image. Lossless compression generally, but not always, results in larger files than lossy compression. Lossless compression should be used to avoid accumulating stages of re-compression when editing images. Lossy compression algorithms preserve a representation of the original uncompressed image that may appear to be a perfect copy, but is not a perfect copy. Often lossy compression

924-536: A separate .css file, which reduces complexity and repetition in the structural content; and enable the .css file to be cached to improve the page load speed between the pages that share the file and its formatting. Separation of formatting and content also makes it feasible to present the same markup page in different styles for different rendering methods, such as on-screen, in print, by voice (via speech-based browser or screen reader ), and on Braille-based tactile devices. CSS also has rules for alternate formatting if

990-558: A single element. Pseudo-classes are used in CSS selectors to permit formatting based on information that is not contained in the document tree. One example of a widely used pseudo-class is : hover , which identifies content only when the user "points to" the visible element, usually by holding the mouse cursor over it. It is appended to a selector as in a : hover or # elementid : hover . A pseudo-class classifies document elements, such as : link or : visited , whereas

1056-420: A single transparent color. Compared to JPEG, PNG excels when the image has large, uniformly colored areas. Even for photographs – where JPEG is often the choice for final distribution since its lossy compression typically yields smaller file sizes – PNG is still well-suited to storing images during the editing process because of its lossless compression. PNG provides a patent-free replacement for GIF (though GIF

1122-619: A site or even across sites, promoting consistency and efficiency. For example, headings ( h1 elements), sub-headings ( h2 ), sub-sub-headings ( h3 ), etc., are defined structurally using HTML. In print and on the screen, choice of font , size , color and emphasis for these elements is presentational . Before CSS, document authors who wanted to assign such typographic characteristics to, say, all h2 headings had to repeat HTML presentational markup for each occurrence of that heading type. This made documents more complex, larger, and more error-prone and difficult to maintain. CSS allows

1188-444: A style sheet, allowing for shorter CSS. Inheritance in CSS is not the same as inheritance in class-based programming languages , where it is possible to define class B as "like class A, but with modifications". With CSS, it is possible to style an element with "class A, but with modifications". However, it is not possible to define a CSS class B like that, which could then be used to style multiple elements without having to repeat

1254-434: A summary of selector syntax indicating usage and the version of CSS that introduced it. A declaration block consists of a pair of braces ( {} ) enclosing a semicolon-separated list of declarations . Each declaration itself consists of a property , a colon ( : ), and a value . Optional white-space may be around the declaration block, declarations, colons, and semi-colons for readability. Properties are specified in

1320-528: Is ASCII for "MNG" – see Portable Network Graphics: File header ) and the use of a much greater variety of chunks to support all the animation features that it provides. Images to be used in the animation are stored in the MNG file as encapsulated PNG or JNG images. Two versions of MNG of reduced complexity are also defined: MNG-LC (low complexity) and MNG-VLC (very low complexity). These allow applications to include some level of MNG support without having to implement

1386-474: Is a file format for 2D vector graphics , raster graphics, and text , and is defined by ISO / IEC 8632 . All graphical elements can be specified in a textual source file that can be compiled into a binary file or one of two text representations. CGM provides a means of graphics data interchange for computer representation of 2D graphical information independent from any particular application, system, platform, or device. It has been adopted to some extent in

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1452-464: Is able to achieve smaller file sizes than lossless compression. Most lossy compression algorithms allow for variable compression that trades image quality for file size. Including proprietary types, there are hundreds of image file types. The PNG, JPEG, and GIF formats are most often used to display images on the Internet. Some of these graphic formats are listed and briefly described below, separated into

1518-403: Is an intermediate format. Most applications open metafiles and then save them in their own native format. Page description language refers to formats used to describe the layout of a printed page containing text, objects and images. Examples are PostScript , PDF and PCL . JPEG (Joint Photographic Experts Group) is a lossy compression method; JPEG-compressed images are usually stored in

1584-470: Is backwards compatible with PNG and supported by most browsers. JPEG 2000 is a compression standard enabling both lossless and lossy storage. The compression methods used are different from the ones in standard JFIF/JPEG; they improve quality and compression ratios, but also require more computational power to process. JPEG 2000 also adds features that are missing in JPEG. It is not nearly as common as JPEG, but it

1650-480: Is designed to be usable for both delivery and authoring use cases. The TIFF ( Tag Image File Format ) format is a flexible format usually using either the TIFF or TIF filename extension. The tag structure was designed to be easily extendible, and many vendors have introduced proprietary special-purpose tags – with the result that no one reader handles every flavor of TIFF file. TIFFs can be lossy or lossless, depending on

1716-408: Is designed to enable the separation of content and presentation , including layout , colors , and fonts . This separation can improve content accessibility , since the content can be written without concern for its presentation; provide more flexibility and control in the specification of presentation characteristics; enable multiple web pages to share formatting by specifying the relevant CSS in

1782-540: Is itself now patent-free) and can also replace many common uses of TIFF. Indexed-color, grayscale, and truecolor images are supported, plus an optional alpha channel. The Adam7 interlacing allows an early preview, even when only a small percentage of the image data has been transmitted — useful in online viewing applications like web browsers . PNG can store gamma and chromaticity data, as well as ICC profiles , for accurate color matching on heterogeneous platforms. Animated formats derived from PNG are MNG and APNG , which

1848-585: Is not widely supported.) The GIF ( Graphics Interchange Format ) is in normal use limited to an 8-bit palette, or 256 colors (while 24-bit color depth is technically possible). GIF is most suitable for storing graphics with few colors, such as simple diagrams, shapes, logos, and cartoon style images, as it uses LZW lossless compression, which is more effective when large areas have a single color, and less effective for photographic or dithered images. Due to GIF's simplicity and age, it achieved almost universal software support. Due to its animation capabilities, it

1914-505: Is positively correlated with the number of pixels in the image and the color depth (bits per pixel). Images can be compressed in various ways, however. A compression algorithm stores either an exact representation or an approximation of the original image in a smaller number of bytes that can be expanded back to its uncompressed form with a corresponding decompression algorithm. Images with the same number of pixels and color depth can have very different compressed file size. Considering exactly

1980-487: Is still widely used to provide image animation effects, despite its low compression ratio compared to modern video formats. The PNG ( Portable Network Graphics ) file format was created as a free, open-source alternative to GIF. The PNG file format supports 8-bit (256 colors) paletted images (with optional transparency for all palette colors) and 24-bit truecolor (16 million colors) or 48-bit truecolor with and without alpha channel – while GIF supports only 8-bit palettes with

2046-461: Is the format for HDR images originating from Radiance and also supported by Adobe Photoshop. JPEG-HDR is a file format from Dolby Labs similar to RGBE encoding, standardized as JPEG XT Part 2. JPEG XT Part 7 includes support for encoding floating point HDR images in the base 8-bit JPEG file using enhancement layers encoded with four profiles (A-D); Profile A is based on the RGBE format and Profile B on

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2112-584: Is their simple structure and wide acceptance in Windows programs. Netpbm format is a family including the portable pixmap file format (PPM), the portable graymap file format (PGM) and the portable bitmap file format (PBM). These are either pure ASCII files or raw binary files with an ASCII header that provide very basic functionality and serve as a lowest common denominator for converting pixmap, graymap, or bitmap files between different platforms. Several applications refer to them collectively as PNM (" P ortable

2178-409: Is used currently in professional movie editing and distribution (some digital cinemas, for example, use JPEG 2000 for individual movie frames). WebP is an open image format released in 2010 that uses both lossless and lossy compression. It was designed by Google to reduce image file size to speed up web page loading: its principal purpose is to supersede JPEG as the primary format for photographs on

2244-509: The JFIF (JPEG File Interchange Format) or the Exif (Exchangeable image file format) file format. The JPEG filename extension is JPG or JPEG . Nearly every digital camera can save images in the JPEG format, which supports eight-bit grayscale images and 24-bit color images (eight bits each for red, green, and blue). JPEG applies lossy compression to images, which can result in a significant reduction of

2310-603: The CMYK defined by a particular set of printing press inks. OCR (Optical Character Recognition) software packages commonly generate some form of TIFF image (often monochromatic ) for scanned text pages. The BMP file format (Windows bitmap) is a raster-based device-independent file type designed in the early days of computer graphics. It handles graphic files within the Microsoft Windows OS. Typically, BMP files are uncompressed, and therefore large and lossless; their advantage

2376-521: The World Wide Web , just as PNG had done for still images. However, with the expiration of LZW patents and existence of alternative file formats such as APNG, Flash and SVG , combined with lack of MNG-supporting viewers and services, web usage was far less than expected. The structure of MNG files is essentially the same as that of PNG files, differing only in the slightly different signature ( 8A 4D 4E 47 0D 0A 1A 0A in hexadecimal , where 4D 4E 47

2442-637: The World Wide Web Consortium to address the need (and attempts of several corporations) for a versatile, scriptable and all-purpose vector format for the web and otherwise. The SVG format does not have a compression scheme of its own, but due to the textual nature of XML , an SVG graphic can be compressed using a program such as gzip . Because of its scripting potential, SVG is a key component in web applications : interactive web pages that look and act like applications. These are formats containing both pixel and vector data, possible other data, e.g.

2508-532: The CSS standard. Each property has a set of possible values. Some properties can affect any type of element, and others apply only to particular groups of elements. Values may be keywords, such as "center" or "inherit", or numerical values, such as 200px (200 pixels), 50vw (50 percent of the viewport width) or 80% (80 percent of the parent element's width). Color values can be specified with keywords (e.g. " red "), hexadecimal values (e.g. # FF0000 , also abbreviated as # F00 ), RGB values on

2574-474: The HTML. CSS lets authors move much of that information to another file, the style sheet, resulting in considerably simpler HTML. And additionally, as more and more devices are able to access responsive web pages, different screen sizes and layouts begin to appear. Customizing a website for each device size is costly and increasingly difficult. The modular nature of CSS means that styles can be reused in different parts of

2640-459: The MNG specification was released on 31 January 2001. Gwenview has native MNG support. GIMP can export images as MNG files. Imagemagick can create a MNG file from a series of PNG files. With the MNG plugin, Irfanview can read a MNG file. If MPlayer is linked against libmng, it and all its graphical front-ends like Gnome MPlayer can display MNG files. Mozilla browsers and Netscape 6.0, 6.01 and 7.0 included native support for MNG until

2706-475: The PNG developers felt that overloading a single file type with both still and animation features is a bad design, both for users (who have no simple way of determining to which class a given image file belongs) and for web servers (which should use a MIME type starting with image/ for stills and video/ for animations—GIF notwithstanding), but work soon started on MNG as an animation-supporting version of PNG. Version 1.0 of

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2772-597: The XDepth format from Trellis Management. The High Efficiency Image File Format (HEIF) is an image container format that was standardized by MPEG on the basis of the ISO base media file format . While HEIF can be used with any image compression format, the HEIF standard specifies the storage of HEVC intra-coded images and HEVC-coded image sequences taking advantage of inter-picture prediction. AV1 Image File Format (AVIF) standardized by

2838-413: The areas of technical illustration and professional design , but has largely been superseded by formats such as SVG and DXF . The Gerber format (aka Extended Gerber, RS-274X) is a 2D bi-level image description format developed by Ucamco . It is the de facto standard format for printed circuit board or PCB software. SVG ( Scalable Vector Graphics ) is an open standard created and developed by

2904-415: The basic use case of WebP (i.e., a file containing a single image encoded as a VP8 key frame). The WebP container provides additional support for: Most typical raster formats cannot store HDR data (32 bit floating point values per pixel component), which is why some relatively old or complex formats are still predominant here, and worth mentioning separately. Newer alternatives are showing up, though. RGBE

2970-690: The code was removed in 2003 due to code size and little actual usage, causing complaints on the Mozilla development site. Mozilla later added support for APNG as a simpler alternative. Similarly, early versions of the Konqueror browser included MNG support but it was later dropped. MNG support was never included in Google Chrome , Internet Explorer , Opera , or Safari . Web servers generally don't come pre-configured to support MNG files. The MNG developers had hoped that MNG would replace GIF for animated images on

3036-470: The content is accessed on a mobile device . The name cascading comes from the specified priority scheme to determine which declaration applies if more than one declaration of a property match a particular element. This cascading priority scheme is predictable. The CSS specifications are maintained by the World Wide Web Consortium (W3C). Internet media type ( MIME type ) text/css is registered for use with CSS by RFC 2318 (March 1998). The W3C operates

3102-428: The decimal system, commas are used to separate the "digits" (a CSS rule having 11 elements and 11 classes would have a specificity of 11,11, not 121). Thus the selectors of the following rule result in the indicated specificity: Consider this HTML fragment: In the above example, the declaration in the style attribute overrides the one in the <style> element because it has a higher specificity, and thus,

3168-627: The designers, or may remove all added styles, and view the site using the browser's default styling, or may override just the red italic heading style without altering other attributes. Browser extensions like Stylish and Stylus have been created to facilitate the management of such user style sheets. In the case of large projects, cascading can be used to determine which style has a higher priority when developers do integrate third-party styles that have conflicting priorities, and to further resolve those conflicts. Additionally, cascading can help create themed designs, which help designers fine-tune aspects of

3234-902: The entire MNG specification, just as the SVG standard offers the "SVG Basic" and "SVG Tiny" subsets. MNG does not have a registered MIME media type, but video/x-mng or image/x-mng can be used. MNG animations may be included in HTML pages using the <embed> or <object> tag. MNG can either be lossy or lossless, depending whether the frames are encoded in PNG (lossless) or JNG (lossy). Most modern web browsers support animations in APNG , SVG , WebP , and WebM . As of February 2024 only Apple Safari supports HEIF and JPEG XL . The most common alternatives have been Animated GIF and – up until its deprecation in 2017 – Adobe Flash . GIF images are restricted to 256 colors with limited compression, but

3300-403: The file size. Applications can determine the degree of compression to apply, and the amount of compression affects the visual quality of the result. When not too great, the compression does not noticeably affect or detract from the image's quality, but JPEG files suffer generational degradation when repeatedly edited and saved. (JPEG also provides lossless image storage, but the lossless version

3366-714: The format is supported in all graphical web browsers and is still widely used. Animations can be generated ad hoc in a browser with the CSS 3 features animations , transitions, and sprites , or also the JavaScript web animations API , by specifying frames or motions of still images or rendered shapes. This can be resource-intensive, and the animation generally cannot be saved in a portable image file or posted on imageboards . Internet Explorer only supported GIF, CSS, and Flash animations. Graphics file format Raster formats are for 2D images . A 3D image can be represented within

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3432-407: The highest priority source are passed on to a source of lower priority, such as the user agent style. The process is called cascading . One of the goals of CSS is to allow users greater control over presentation . Someone who finds red italic headings difficult to read may apply a different style sheet. Depending on the browser and the website, a user may choose from various style sheets provided by

3498-412: The interactive features of PDF. Cascading Style Sheets#CSS 3 Cascading Style Sheets ( CSS ) is a style sheet language used for specifying the presentation and styling of a document written in a markup language such as HTML or XML (including XML dialects such as SVG , MathML or XHTML ). CSS is a cornerstone technology of the World Wide Web , alongside HTML and JavaScript . CSS

3564-429: The modifications. Given the following style sheet: Suppose there is a p element with an emphasizing element ( <em> ) inside: If no color is assigned to the em element, the emphasized word "illustrate" inherits the color of the parent element, p. The style sheet p has the color pink, hence, the em element is likewise pink: This is to illustrate inheritance The whitespace between properties and selectors

3630-1096: The paragraph appears green: To demonstrate specificity Inheritance is a key feature in CSS; it relies on the ancestor-descendant relationship to operate. Inheritance is the mechanism by which properties are applied not only to a specified element but also to its descendants. Inheritance relies on the document tree, which is the hierarchy of XHTML elements in a page based on nesting. Descendant elements may inherit CSS property values from any ancestor element enclosing them. In general, descendant elements inherit text-related properties, but their box-related properties are not inherited. Properties that can be inherited are color, font, letter spacing, line-height, list-style, text-align, text-indent, text-transform, visibility, white-space, and word-spacing. Properties that cannot be inherited are background, border, display, float and clear, height, and width, margin, min- and max-height and -width, outline, overflow, padding, position, text-decoration, vertical-align, and z-index. Inheritance can be used to avoid declaring certain properties over and over again in

3696-542: The rendered measurement. These eight units were a feature of CSS 1 and retained in all subsequent revisions. The proposed CSS Values and Units Module Level 3 will, if adopted as a W3C Recommendation, provide seven further length units: ch ; Q ; rem ; vh ; vmax ; vmin ; and vw . Before CSS, nearly all presentational attributes of HTML documents were contained within the HTML markup. All font colors, background styles, element alignments, borders, and sizes had to be explicitly described, often repeatedly, within

3762-602: The same compression, number of pixels, and color depth for two images, different graphical complexity of the original images may also result in very different file sizes after compression due to the nature of compression algorithms. With some compression formats, images that are less complex may result in smaller compressed file sizes. This characteristic sometimes results in a smaller file size for some lossless formats than lossy formats. For example, graphically simple images (i.e. images with large continuous regions like line art or animation sequences) may be losslessly compressed into

3828-463: The selectors is important. For example, div . myClass { color : red ;} applies to all elements of class myClass that are inside div elements, whereas . myClass div { color : red ;} applies to all div elements that are inside elements of class myClass. This is not to be confused with concatenated identifiers such as div . myClass { color : red ;} which applies to div elements of class myClass. The following table provides

3894-431: The separation of presentation from structure. CSS can define color, font, text alignment, size, borders, spacing, layout and many other typographic characteristics, and can do so independently for on-screen and printed views. CSS also defines non-visual styles, such as reading speed and emphasis for aural text readers. The W3C has now deprecated the use of all presentational HTML markup. For example, under pre-CSS HTML,

3960-499: The style element: All h1 elements in the document will then automatically become red without requiring any explicit code. If the author later wanted to make h1 elements blue instead, this could be done by changing the style element to: rather than by laboriously going through the document and changing the color for each individual h1 element. The styles can also be placed in an external CSS file, as described below, and loaded using syntax similar to: This further decouples

4026-418: The styles cannot be loaded or are disabled, this separation maintains the accessibility and readability of the content, ensuring that the site is usable for all users, including those with disabilities. Its multi-faceted approach, including considerations for selector specificity, rule order, and media types, ensures that websites are visually coherent and adaptive across different devices and user needs, striking

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4092-639: The styling from the HTML document and makes it possible to restyle multiple documents by simply editing a shared external CSS file. CSS, or Cascading Style Sheets, offers a flexible way to style web content, with styles originating from browser defaults, user preferences, or web designers. These styles can be applied inline, within an HTML document, or through external .css files for broader consistency. Not only does this simplify web development by promoting reusability and maintainability, it also improves site performance because styles can be offloaded into dedicated .css files that browsers can cache. Additionally, even if

4158-543: The technique chosen for storing the pixel data. Some offer relatively good lossless compression for bi-level (black&white) images . Some digital cameras can save images in TIFF format, using the LZW compression algorithm for lossless storage. TIFF image format is not widely supported by web browsers, but it remains widely accepted as a photograph file standard in the printing business. TIFF can handle device-specific color spaces, such as

4224-520: The two main families of graphics: raster and vector. Raster images are further divided into formats primarily aimed at (web) delivery (i.e. supporting relatively strong compression) versus formats primarily aimed at authoring or interchange (uncompressed or only relatively weak compression). In addition to straight image formats, Metafile formats are portable formats which can include both raster and vector information. Examples are application-independent formats such as WMF and EMF . The metafile format

4290-599: The video consortium Alliance for open media (AOMedia) creator of the video format Av1 , to take advantage of modern compression algorithms and a completely royalty-free image format. It uses the image format with AVIF coding and recommends using the HEIF container, see AV1 in HEIF . JPEG XL is a royalty-free raster-graphics file format that supports both lossy and lossless compression. It supports reversible recompression of existing JPEG files, as well as high-precision HDR (up to 32-bit floating point values per pixel component). It

4356-416: The web. WebP is based on VP8 's intra-frame coding and uses a container based on RIFF . In 2011, Google added an "Extended File Format" allowing WebP support for animation , ICC profile , XMP and Exif metadata , and tiling. The support for animation allowed for converting older animated GIFs to animated WebP. The WebP container (i.e., RIFF container for WebP) allows feature support over and above

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