Home > Articles

Advantages of PNG

Out of the box, .png has several advantages over .gif. Not all of these advantages are used yet to their fullest potential, and, like any new technology, some people have not yet joined the party.

Alpha Channel Transparency

The real coup is the use of an alpha channel to give the option of using 8 bits for transparency rather than .gif's single bit (a pixel on a .gif is either transparent or it's not—a pixel in a .png file can have any one of 254 levels of transparency). This means that you can do nifty things such as make an image that includes a transparent drop shadow. This is important when creating professional-looking, reusable graphics. Single-bit transparency would give a shadow that covers the original background color that the image was drawn over. Using the alpha channel means that you can create a real shadow, which is colored by whatever colors or images are underneath.

This transparency feature is far more important for the small Web graphics that typically are used on Web pages, such as colored (circular) bullets and fancy text. Alpha blending allows you to use antialiasing—creating the illusion of smooth curves on a grid of rectangular pixels by smoothly varying the pixels' colors—to make rounded and curved images that look good against any background, not just against a white background, for example. Thus, the same image can be reused in many places without the "ghosting" effect that occurs with GIFs.

Recent versions of Photoshop (5.5 and above) and Paint Shop Pro (7.0 and above) offer features that directly support the use of 8-bit transparency (such as Photoshop's Export To Web); older graphics programs had not yet embraced the format.

Gamma Correction Control

Gamma controls the brightness and saturation of an image on a monitor. Gamma "correction" refers to the ratio of the actual value of the color (the values 2, 153, and 202, for example, produce a nice shade of blue in RGB parlance) compared to the inherent brightness of the monitor. Proper gamma control ensures that the image shows up on the monitor at the proper level of brightness and proper color saturation so the image does not look washed out. Most monitors today require a gamma correction value of 2.5, but that does not necessarily mean that all computer systems should use 2.5 as the gamma correction value.

When Apple designed the Macintosh computer, it had graphic designers in mind and took gamma into consideration, giving its computers built-in system gamma correction. After the software puts the graphic image into the frame buffer, the hardware does a gamma correction of 1.4. Therefore, a PNG created on a Macintosh would use a gamma correction value of 1.8 (which is 2.5 divided by 1.4). Other systems that have built-in, or system, gamma correction are SGI and NeXT computers. PCs and popular UNIX workstations such as Sun have no "system" gamma correction and require the full 2.5 gamma correction value. Images in the PNG format contain the gamma correction value used when creating the image and, when displayed, allow the viewing system to correct the gamma and display properly on all systems.

File Size

Typically, .png files compress better than .gifs. Using a utility such as pngcrush can further reduce the size of your PNG files, but your mileage will vary. The following set of images is the same picture in a variety of saved image formats. The .png actually appears smaller than the lossy .jpg; however, the .png file is only 8-bit (as is the .gif file). At true color, which is 32 bits, the .png file is actually larger than the .jpeg file. The GIF format is incapable of saving files with more than 8 bits of color. The important point to keep in mind here is that the image fidelity in PNG images is maintained because of the lossless compression algorithms used. JPEG images lose image information each time they are saved. Additionally, the compression algorithms in JPEG have a tendency to create artifacts in the image that become annoyingly visible as the compression goes higher.

Figure 1 A 37k .jpg file, with 1% compression.

Figure 2 A 3k .jpg file, with 80% compression.

Figure 3 A 37k .gif image.

Figure 4 A 32k .png with 256 colors.


Not using the LZW algorithm for compression makes the .png format truly free. Not that you ever would have paid for your individual .gif images (and not like you won't continue to pay for a license when you buy a product like Photoshop), but you no longer have to lead the guilty life of an intellectual property thief.

Because of the lack of patent and licensing issues, PNG has become the darling format for software developers and Internet standards stalwarts who demand open standards. Because software developers do not have to negotiate a license to use LZW compression, they can charge a lower price for their software. And because open-source and free-software authors try to avoid promoting any software patents, the default image format for most free software projects is PNG.

Support for Greater Bit Depths

The PNG format supports up to 48-bit true-color or 16-bit grayscale images. GIF images can support only 256 colors (or 255 colors and transparency), and JPEG supports 24-bit color images. Using PNG can provide you with a flexible image format that scales up or down to meet your image needs.

Lossless Compression

Saving, opening, and resaving an image will not degrade its quality. Compression algorithms work by looking for redundant data in a file and replacing this with a smaller, representational "nickname." Lossy algorithms are more efficient because they don't require an exact match in redundant data—merely "close enough" is good enough. There are all sorts of techniques to reduce the visibility of throwing away perfectly good data, and they have to do mainly with human perception thresholds and rules of thumb. This works well for photographs in which areas of great similarity often exist (such as a blue expanse of sky), but not as well for images that involve text—and not at all for files whose integrity must be kept (such as text files or programs). Lossless algorithms don't compress as well, but they encode and decode all the data with exact fidelity.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020