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PNG

PNG Files

Portable Network Graphics

PNG is a lossless raster image format for web graphics, screenshots, logos, transparency, and color-managed bitmap images.

Portable Network Graphics (PNG)

Developer
PNG Development Group / W3C
Category
Images
MIME type
image/png
Format
Binary
Magic bytes
89 50 4E 47 0D 0A 1A 0A
First released
1996
Latest version
Third Edition / ISO/IEC 15948:2004 (W3C PNG 3rd ed., 2025)
Open standard
Yes

Open a .PNG file online

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What is a .PNG file?

PNG usually stands for "Portable Network Graphics" - the format was created as a bitmap raster file, lossless image format invented by the PNG Development Group in 1996, to replace the patented file format GIF. In general PNG saves rectangular pixel images and thus, is mostly used to save photographs, screenshots, UI elements, logos, drawings and charts, icons, textures for computer games, science graphics. In addition, this raster graphic format is a native format for a majority of web-browsers and supports all features such as alpha transparency, palette-colored images, grayscale and full color.

Currently there are no other file types (besides of PNG) using .PNG file extension. If you get opened file which claims to be PNG but doesn't present an image then this file can be damaged file or just renamed file. Valid PNG file must be identified easily according to its 8 bytes signature, which starts at offset zero: 89 50 4E 47 0D 0A 1A 0A.

In addition PNGs cannot store vector artwork nor layers because these raster pixel files were not designed primarily to create vector art with high resolution. PSDs, XCFs or vector file SVG and AI and many more layered application-specific are used as source for editing. When creating photographic images PNG cannot compete with JPEG, WebP or AVIF for example.

How to open a .PNG file

Open a .PNG file on Windows

  1. 1 Go to the folder with your file in File Explorer. Usually, downloaded files end up in Downloads.
  2. 2 Double-click your .PNG file if you have an app for .png files on your computer. In case it does not open, move on to step three.
  3. 3 Right-click your .PNG file -> select Open with -> Choose another app.
  4. 4 Choose Microsoft Photos in the list (Windows 11: choose Always). For Windows 10 -> put a check on "Always use this app to open .png files" and click OK.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for Windows

Open a .PNG file on macOS

  1. 1 In the Finder app, locate your .PNG file.
  2. 2 Just double-click your .PNG file in order to automatically launch the program which is connected with it.
  3. 3 Need another app on your Mac? Control-click the file (or right-click with a mouse). In the pop-up menu select Open With -> Apple Preview.
  4. 4 If it isn't in the list, choose Other… and find the application manually.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for macOS

Open a .PNG file on Linux

  1. 1 Launch your file manager. Depending on the desktop it may be named Files (GNOME), Dolphin (KDE Plasma), Nemo (Cinnamon) or Thunar (Xfce).
  2. 2 Double-click the file.
  3. 3 Or choose another program by right-clicking the file -> Open With -> XnView MP.
  4. 4 Install XnView MP (if it is not installed on your computer) from the software centre, repository or Flathub.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for Linux

Open a .PNG file on Android

  1. 1 Launch Files or another file management app.
  2. 2 In Downloads, find the .PNG file and open it by tapping.
  3. 3 A list of apps capable of opening the file will be shown. Tap a suitable app and press Always to permanently connect the file type with this app.
  4. 4 No apps able to open this file? Download a suitable app from the Google Play Store.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for Android

Open a .PNG file on iPhone / iPad

  1. 1 Use the Files app and go to On My iPhone, iCloud Drive or Downloads.
  2. 2 Tap the .PNG file you want to open.
  3. 3 If the file can be opened by a built-in iOS app (supported format), it opens automatically.
  4. 4 Touch and hold the file to get the context menu -> choose Share -> select a suitable app from the list of apps.
  5. 5 If there is no such option, download the app first from the App Store and then tap the document again.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for iPhone / iPad

Open a .PNG file online

  1. 1 Move to the online viewer at the top of this page.
  2. 2 Drag the file there or select it, and its contents will appear in your browser tab. The file is not uploaded.

Still not opening? See common problems and fixes, or view it in your browser.

Programs for Online

More details about opening .PNG files

For PNG on Windows, you can use Microsoft Photos, Paint, Paint.NET, IrfanView, XnView MP, Adobe Photoshop, web browsers, most Office apps. Microsoft Photos and Paint are ideal for basic tasks like viewing, formatting and Paint.NET, IrfanView, and XnView MP will do a better job when you need to manipulate images by resizing, converting to another format and verifying metadata. Adobe Photoshop would be used for complex manipulations in a layered environment and would require you to purchase it. For macOS, your fastest bet is Preview or Quick Look, but you could also use Photos, Pixelmator Pro, Photoshop, GIMP, browser applications like Safari, Chrome or Firefox that can open PNGs. Preview and GIMP are free; Pixelmator Pro and Photoshop will have you paying a fee. PNG would likely open through Eye of GNOME or Loupe (GNOME); Gwenview (KDE), Shotwell, GIMP, Krita, ImageMagick and even web browsers. When batch processing is important ImageMagick and XnView MP are recommended due to supporting all major operations including metadata manipulation, conversions and rescaling. Most smartphones running on Android and iPhones have the gallery or the built-in photo app that handles PNG as well as file viewers, browsers, web applications like Google Photos. Browsers will allow direct visualization; photo editing and image manipulations are available through Krita or Procreate apps, file manager apps. In the web-browser environment PNG opens on tab and in some online editor including Canva and Photopea.

If the double-click does not help to open it then first make sure the file ending is really ".png", try opening from a web browser or an app as mentioned here, reset the default app. In case one application says it is unsupported file type you can verify it is really PNG using hexadecimal view or a Unix-based computer can try 'file [filename]'.

Technical details

PNG consists of an 8-byte sequence at offset 0: 89 50 4E 47 0D 0A 1A 0A, followed by chunks with 4 bytes indicating the length, 4 character type code, followed by data, and 4 bytes of checksum - cyclic redundancy check. Every valid PNG file starts with IHDR chunk which holds image information such as width, height, bit depth, color types among other parameters; the file ends with IEND chunk. IDAT contains a compression of data while there can also be one or more ancillary chunks to hold palette information (PLTE) or transparency (tRNS), Gamma value (gAMA), Chromaticity (cHRM), embedded profile (iCCP) , text strings(tEXt, zTXt, iTXt), timestamps in tIME or application data chunks. The raw pixels in PNGs are stored scanline by line with each row undergoing the use of five different filter mechanisms before compression. The filtered pixel byte streams are further compressed through use of the DEFLATE within the Zlib format in PNG encoding. Lossless compression algorithm is used that is independent on how the image is semantically meaningful with screenshots being the same for scientific images and logos. Standard PNG encoding uses grayscale, RGB truecolor, indexed color palettes, grayscale and truecolor having alpha component. Bit depths supported for various images includes 1, 2, 4, 8 or 16 depending on what image you have as color type and transparency for PNG can be achieved through full alpha component channels and also for palettised image through the tRNS chunks. In PNG there is the Adam7 interlace technique of progressive seven pass interlacing while PNG is generally not interlaced. Registered MIME Type is image/png and image files will normally have sizes depending on complexity going upwards of 10 KBs all the way up to tens of MBs for large or high bit depths such as 16-bit. PNG Third Edition was published by W3C in 2025; the ISO version is ISO/IEC 15948:2004.

How to convert .PNG files

Converting PNG to JPEG in situations where there's no requirement to maintain alpha-transparency. This would be done by flattening the transparency in PNG onto white and subsequently exporting via command 'magick input.png -background white -alpha remove -alpha off output.jpg'. In JPEG conversion, pixel details are lost because it's a lossy conversion process leading to edge artifacts such as blockiness, banding, ringing and other effects like blurry text.

Smaller file sizes of image can be created via converting to WebP and AVIF. Examples: 'magick input.png -quality 85 output.webp' or 'magick input.png -quality 50 output.avif'. Verify client browsers support these images and change quality settings since they allow for both lossy and lossless compression and lossy mode will permanently alter pixel contents.

Convert from PNG to TIFF when printing, preparing files for scanning, prepress production work, geographic information systems, scientific research using microscopes, archival projects that need TIFF format, plus when there's a need for richer tagging in an image file. Convert to PDF when a one-off page is required, e.g., email attachment of file: 'magick input.png output.pdf'; additional tool OCR might become important if there's need for searchable text in image file. The reason for creating BMP from PNG is for compatibility with old-fashioned Windows applications, firmware processing pipelines and very old file formats: 'magick input.png output.bmp'.

Resizing and changing formats simultaneously would provide more savings over changing formats alone. It can be accomplished through ImageMagick and GUI exporters resize functions. Export to SVG would be useless if one does not use vector tracing beforehand.

Convert toToolCommand / note
JPEG/JPG ImageMagick magick input.png -background white -alpha remove -alpha off output.jpg Use for photos and smaller web files; alpha transparency is flattened and lossless pixels become lossy JPEG.
WebP ImageMagick magick input.png -quality 85 output.webp Often smaller for web delivery; WebP can be lossless or lossy and supports alpha in modern browsers.
AVIF ImageMagick magick input.png -quality 50 output.avif High compression for websites; decoding support is newer and encoding may be slow.
TIFF ImageMagick magick input.png output.tiff Useful for print, scanning, and archival workflows; preserves lossless raster data but can greatly increase file size.
BMP ImageMagick magick input.png output.bmp Creates a simple uncompressed or lightly encoded bitmap for legacy Windows software; transparency and metadata support are limited.
PDF ImageMagick magick input.png output.pdf Wraps the bitmap in a PDF page for sharing or printing; it does not make text editable or vectorize the image.
SVG Inkscape inkscape input.png --export-type=svg --export-filename=output.svg This embeds the raster PNG in an SVG document, not automatic vector tracing; use tracing separately if vector paths are required.

Common problems and fixes

"Not a PNG file" or "file signature not found" means that the initial eight bytes are not equal to 89 50 4E 47 0D 0A 1A 0A. Download the file once again and find out if it is not HTML, JPEG, or WebP with some changed extension. The process of saving in any web-browser often produces an HTML file which is perceived as image file name.

"CRC error" is used for indicating the discrepancy in checksum calculation in one of the PNG file's chunks. Usually the issue occurs due to corruption and bad transferring. It is recommended to get the same file again. Even damaged ancillary data can be successfully repaired when all IDAT chunks stay safe.

"The unexpected end of file" normally says that the transfer was completed prior to the IEND. One must compare the sizes of files (source and local) and transfer the file again. The "IHDR: CRC error" and "invalid IHDR data" are much worse; in IHDR one may find all important info, including information about image's sizes and depth of color. It is extremely hard to reproduce this info in case if header is damaged.

Really large PNG images can create the out-of-memory error. This is because the decoder transforms the compressed information into decompressed buffer with a certain size. One should use tiled image viewing software (for example, GIMP, Krita, and others). It is possible to downscale these files using ImageMagick and a proper memory allowance. Some older decoders could not properly decode the information with 16-bit channels and APNG, iCCP, or sRGB information chunks. The viewer update or elimination of metadata chunks helps solve these problems. A black or white background instead of transparency is due to incorrect settings in the compositing program. Washed out appearance is the indication of the unconsidered gAMA, sRGB, or iCCP chunks.

Security considerations

The PNG format does not have any macros, no embedded executables, or scripts; this reduces the chance of malware execution upon viewing in Chrome/ Firefox, Preview, or Photos compared to opening Microsoft Office formats. The major vulnerability of PNGs are decoder-based, such as buffer and integer overflow, improper use of zlib routines, and various bugs in decoding libraries and application wrapping programs like libpng. Open unknown PNG files in your current browser/image viewer and don't include deprecated image libraries into the uploading pipeline on your web-server.

PNG file can also include the metadata which includes the Exif data, time stamp, color information or additional data, comments, and tool identification. Exiftool, ImageMagick, pngcrush, editing applications are some of the applications one can use in order to remove metadata prior to publication. Check the MIME type on the server and PNG signature: [PNG signature is "89 50 4E 47 0D 0A 1A 0A"]. Make sure that you have some limits on pixel count. PNG file extension does not ensure the security. You also can embed data via pixel values or ancillary chunks, but it has no encrypting options.

History and versions

Development of PNG began back in 1995 as the consequence of the controversy between UNISYS LZW patent. In its core, it was about creating an open, lossless file format for the web. The specification was developed by the PNG Development Group along with some individual authors including Thomas Boutell and PNG 1.0 appeared already in 1996. PNG became a W3C recommendation in the same year and, afterwards, RFC 2083. As for the development goal, the new technology aimed at enhancement of GIF adding truecolor palette, alpha-channel, proper gamma and compression. PNG 1.1 standard occurred back in 1998 and, in 1999, came the standard of PNG 1.2, improving specifications, adding consistent ancillaries like 'iTXt' international text and, thus marking the peak development period which can be seen in international standard ISO/IEC 15948:2004 based on PNG 1.2. APNG technology which is the animated extension to PNG appeared in the 2000s due to the works of some Mozilla's contributors; but as it is an animated form it doesn't correspond with baselines of PNG 1.2 standard as a self contained still-image format.

JPEG (.jpg, .jpeg) is generally small enough for photos, but as an encoding method it is lossy and does not support standard PNG alpha transparency. Therefore PNG should be preferred for UI elements as PNG format can have transparent background. GIF (.gif) allows up to 256 different colors, may create animation and supports one-color transparency, and PNG image has better quality color range and allows alpha (baseline image format without animation). APNG (or APNG .png - occasionally .apng file extensions) has all features that PNG has and adds animation information and may appear to be useful where animated PNG images are needed as a player may simply read the first frame of animated image. WebP supports lossy, alpha, lossless and animations formats and provides excellent compression algorithm, while using PNG may be preferred to save simplicity for web usage. AVIF format provides good compression of photos and graphics in comparison to PNG but has worse performance.

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