PNG vs JPG: Which One to Choose?

There are plenty of image formats available today, the most popular being PNG and JPG. If you extensively use digital images for web content or your photography work, it is important to know the best file formats to use.

When it comes to the PNG vs JPG battle, not everyone exactly understands the difference. In this article, we look at both image formats, what they are used for, and how they compare.

PNG and JPG vs other formats

So, why are we talking about these two specific file types? There are of course other picture formats – TIFF, BMP, GIF, PSD, and RAW, for example. Why not use one of these instead?

In most instances, JPG or PNG offers the best compression rates and retention of image quality. Furthermore, file types like RAW, and PSD have specialized purposes.

Here's a brief description of these other image types below:

• RAW: Unprocessed file format used in photography.
• TIFF: Large faster file with lossless compression.
• PSD: Native file format for Adobe Photoshop.
• BMP: Raster graphics file with lower quality.
• GIF: Used for short frame-by-frame animations.

As you will see below, JPG and PNG are better suited to have a more universal application than other formats.

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JPG/JPEG format

JPG/JPEG is possibly the most used image file format. It is interoperable – i.e. it can be viewed on many different devices as JPG is not vendor-specific.

It has become the standard for image compression and is widely used to share images as web content.

JPG file format compresses the pixels and image information using DCT (Discrete Cosine Transform) and offers a typical compression ratio of 10:1.

For example, if you had a 10 MB image, and converted it to a JPG, the resulting file size could be as small as 1 MB.

The JPG compression is complex, but in short, it can be described as this. The algorithm analyses the whole image. It then determines which pixels are similar enough that they can be merged and combines them into tiles. The result is a much smaller file size, with an imperceptible loss of quality.

This type of compression has a drawback – JPG images are lossy. This means that each time the file is compressed and saved, data (i.e. pixels) is lost. The process could be compared to photocopying a photocopy.

PNG format

PNG is the other popular image format that is used for a myriad of purposes. Like JPG, it is interoperable and an open file format – this means that it can be viewed through a range of different photo editors.

Also, similarly to JPG, PNG image format provides compression which results in much smaller file sizes, compared to PSD, for example. Due to the compression method, however, PNG files are generally larger in size than JPG.

PNG files use LZW compression (Lempel–Ziv–Welch). This is a form of lossless compression as opposed to the lossy compressing of JPG.

The LZW compression method uses a complex process of code string matching to compress the image, whilst still retaining its original quality.

Extension types

Technical specifications

Understanding the technical structure of PNG and JPG files, including their metadata, headers, and compression algorithms, reveals the differences between these two popular image formats.

PNG images are divided into small blocks called "chunks". Each chunk has specific information like the image data, color details, and any text or metadata. The most important chunk contains the actual pixel data, which is compressed using a method called DEFLATE.

That's why PNG supports transparent areas in a picture, making it useful for logos that need to blend with backgrounds.

JPG images are divided into small parts called "tiles" or "blocks". Each block is processed and compressed separately. The data is converted into a set of mathematical values (using techniques like DCT - Discrete Cosine Transform) and then compressed.

PNG vs JPG: Which is best?

So which file type should you use in different circumstances? We have listed some of the common uses for digital images, and which file type would be suitable below:

The other main difference is that PNG files support transparency. Both color and grayscale pixels in PNG images can be transparent. This means you can use PNG file format to merge graphics seamlessly into background objects.

For example, you could create a company logo as a PNG file, and then overlay this onto any web content, without worrying about matching the background color.

There is no right or wrong answer. You must consider the individual situation and look at what the image is required for, and how it is used:

• When smaller file size is imperative, JPEG is the better choice due to its higher rate of compression without a huge loss of quality.
• If detail and quality matter the most, PNG is the better choice due to its lossless compression and support for transparency.
• Images with text should generally be saved in PNG file format. This is because the PNG file format can render text in a better way. If you save an image with text as a JPG, you will notice that the edges of the words appear jagged – this is due to a lack of anti-aliasing.

A simple rule to remember that often works is that JPG pictures are suited for photographs, whilst PNG images are suitable for creating graphics and taking screenshots.

Compression artifacts

When it comes to handling image degradation over multiple saves or edits, PNG and JPG formats exhibit different behaviors due to their distinct compression methods.

PNG

Because of its lossless compression, PNG pictures maintain their original quality even after multiple saves or edits. Each time a PNG image is re-saved, it retains its clarity, sharpness, and color fidelity without any degradation.

That's why this format is commonly used in graphic design, digital art, and other applications where preserving image integrity is crucial.

JPG

Each time a JPG image is saved, it undergoes additional lossy compression, leading to cumulative quality degradation. This results to compression artifacts and a gradual loss of image quality, particularly in areas with fine details or gradients.

Due to its lossy nature, JPG files are less suitable for editing and manipulating images extensively.

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How to choose between PNG and JPG?

Here's a checklist to help you pick the right format:

1. Image content
   • PNG for images with sharp lines, text, or graphics with solid colors.
   • JPG for photos or images with many colors and gradients.
2. Transparency
   • PNG if your image requires transparency (e.g., logos, icons).
   • JPG if transparency is not important.
3. File size
   • JPG if you need a smaller file size.
   • PNG if file size is less important.
4. Image quality
   • PNG for images where quality is paramount.
   • JPG if you can tolerate some loss of quality.
5. Web use
   • PNG for web graphics that require transparency or crisp lines.
   • JPG for web photos where file size and loading time are important.
6. Editing needs
   • PNG for images that you will edit multiple times.
   • JPG if the image will be saved once and not edited again.
7. Color depth
   • PNG when precise color reproduction is critical.
   • JPG if the slight reduction in color depth and quality is acceptable.

Conclusion

We hope you have found this article dedicated to PNG vs JPG topic useful. You should now have a clear idea of what PNG or JPG image formats have to offer. Furthermore, you should understand appropriate usage and which file format is better suited in certain situations.

This knowledge will help you dive deep into the world of photo editing.

FAQs

Is it possible to convert a PNG image to a JPG without losing quality?

Converting a PNG to a JPG without losing quality is not possible. JPG is a lossy compression format, which means some image details are discarded during compression, resulting in a loss of quality. However, there are tools available that optimize the conversion process to minimize the loss.

Can I resize a PNG image without losing quality?

Yes, PNG images are lossless, allowing resizing without significant quality loss. When scaling down, quality usually remains intact. However, enlarging may lead to slight degradation due to pixelation. To maintain quality, use professional photo editing software or online tools specifically designed for resizing images while preserving quality.

Can I change the dimensions of a JPG photo without downgrading the quality?

Resizing a JPG image can cause quality loss due to compression. Decreasing its size generally retains quality, but enlarging often degrades it, resulting in pixelation and artifacts. To minimize loss, use original or high-resolution images and employ an image resizer designed to preserve quality during resizing.

What is the difference between editing PNG and JPG images?

When editing PNG images, you can make multiple changes while maintaining quality and transparency. In contrast, editing JPG images requires caution to minimize artifacts and quality degradation, especially after multiple saves.

Can PNG or JPG be used for creating animated images or GIFs?

While PNG or JPG formats themselves do not support animation directly, they can be used as frames in creating animated images or GIFs. Specialized software or online tools that support frame-based animation can efficiently utilize PNG or JPG files for animating purposes.

Are there any limitations or considerations when using PNG vs JPG in specific industries, such as graphic design or photography?

In industries like graphic design and photography, the choice between PNG and JPG depends on specific requirements. PNG is typically preferred when working with images that require transparency or need to be edited multiple times without losing quality. JPG is commonly used for high-resolution photographs where smaller file sizes are desirable.

Do certain social media platforms or websites have specific image requirements, making one format more preferable over the other?

Yes, sometimes this is the case. For example, Facebook and Instagram tend to recommend using JPG for regular pictures while suggesting PNG for images with transparency or logo-like visuals.

Are there any experimental or emerging image formats that could potentially replace PNG and JPG in the future?

While new image formats continue to emerge, currently there is no established replacement for PNG or JPG formats that has gained widespread adoption. Formats like WebP and HEIC have shown potential, but their usage is limited to certain platforms and devices.

Are PNG images suitable for printing?

Yes, PNG images are great for printing as they maintain good quality. Especially if the original image has a high resolution and was saved with minimal compression.

Can advanced image editing features, such as layers and transparency effects, be applied to both PNG and JPG files equally?

PNG supports advanced image editing features like layers and transparency effects since it is a lossless format. JPG, being a lossy format, does not support layers or transparency in the same way. Any transparency effects applied to a JPG image will be replaced with solid colors.

Paul Skidmore

Tech Writer and Photography Aficionado

Paul is a self-professed photography and tech nerd and has years of experience working with various editing software. He has a passion for travel and has taken his camera to destinations including Antarctica, Singapore, Indonesia, and Greenland.