Understanding PowerVR Series5XT: PVRTC, PVRTC2 and texture compression

Share on linkedin
Share on twitter
Share on facebook
Share on google

One of the biggest contributors to bandwidth in mobile graphics is the bandwidth linked to texture mapping. This is especially true with increasing screen resolutions, as ever-higher resolution textures are required to maintain image quality, and thus ever more data is being read by the GPU.

Reducing texture bandwidth and power with PVRTC and PVRTC2

Imagination recognised this fact early on. PowerVR MBX was our first PowerVR core for mobile devices that included support for our proprietary PVRTC texture compression. For reference, this was in 2001. More than 12 years ago, we already recognised that reducing texture bandwidth (and related power consumption), as well as reducing the memory footprint and application distribution size were essential for success in the mobile market.

PVRTC and PVRTC2 Image vsTextureCompression

Image compression vs. texture compression

Given that in these early days, silicon area was a key factor for system architectures, the PVRTC decompression hardware was designed to be very small and of course extremely low power. PowerVR customers and partners have benefited from PVRTC compression down to 4 or even only 2 bits per pixel across RGB and RGBA formats ever since 2001, and this revolutionary ability is just one of many that have helped PowerVR become the dominant player in the mobile space.

PVRTC and PVRTC2 Decompression DescriptionAn overview of the PVRTC and PVRTC2 decompression algorithm

Khronos recognised this issue too and started working on the ASTC compression standard in 2012. As of the writing of this post, there are still no devices shipping with this new standard while PVRTC and PVRTC2 can be found in millions of smartphones and tablets worldwide. Even though it has taken this long for the rest of the industry to recognise the need for texture compression, we are glad to see more people acknowledging our assertion that high quality 2bpp (bit per pixel) compression of RGBA texture data is essential.

With PowerVR Series5XT, we’ve introduced an enhanced version of PVRTC which removed several of the original limitations (which existed primarily for silicon area savings). For example, we eliminated assumed wraparound of textures with the introduction of NPOT (Non Power Of Two) support. We also added many other features designed to improve visual quality and allow for advanced texturing, such as atlases.

These improvements resulted in the updated PVRTC2 format . PVRTC2 has even better image quality than the original PVRTC format, which already surpassed the capabilities of DXT1. Many more details about PVRTC, PVRTC2 and their benefits can be found in the whitepaper available on our Developer Technology Website.

A case study of texture compression quality

To have a fair estimate of the quality difference between different compression schemes, we have compressed a set of images that included natural photographs, some actual game textures and some game screenshots. We then computed the average quality difference between the different schemes, using different metrics: SSIM, PSNR and RMS, VIF, etc.


The original images used for the test: Decos_Cover01_D, RGB_OR_1200x1200_010.png and pocket-legends


If you want to get started right away with PVRTC and PVRTC2 compression, we recommend you try out our PVRTexTool package, part of our PowerVR Graphics SDK. PVRTexTool is a suite of utilities for compressing textures which supports PVRTC, PVRTC2 and ETC, as well as all of the core texture formats for a variety of different APIs.

In the next blog post, I will discuss how PowerVR GPUs handle YUV color space conversions more efficiently compared to other graphics processors.

If you have any questions or feedback about Imagination’s graphics IP, please use the comments box below. To keep up to date with the latest developments on PowerVR, follow us on Twitter (@GPUCompute, @PowerVRInsider and @ImaginationTech) and subscribe to our blog feed.

‘Understanding PowerVR’ is an on-going, multi-part series of blog posts from Kristof Beets, Imagination’s Senior Business Development Manager for PowerVR. These articles not only focus on the features that make PowerVR GPUs great, but also provide a detailed look at graphics hardware architectures and software ecosystems in mobile markets.

If you’ve missed any of the posts, here are some backlinks:


Luis Matos has contributed to this article.

Please leave a comment below

Comment policy: We love comments and appreciate the time that readers spend to share ideas and give feedback. However, all comments are manually moderated and those deemed to be spam or solely promotional will be deleted. We respect your privacy and will not publish your personal details.

Blog Contact

If you have any enquiries regarding any of our blog posts, please contact:

United Kingdom

Tel: +44 (0)1923 260 511

Search by Tag

Search for posts by tag.

Search by Author

Search for posts by one of our authors.

Featured posts
Popular posts

Related blog articles

Making Unreal Engine and Unity profiling on PowerVR easier

The PowerVR Developer Technology team has always been fully committed to making development for PowerVR easier, by continually improving our groundbreaking tools and SDK. Our ecosystem is very important to us, so we’re focusing on the things developers really need

Product and event round-up from the experts in GPU and AI

It’s certainly been a busy few months for Imagination. Towards the latter end of last year, we released a raft of new products and initiatives, and a new CEO took the helm giving us real momentum for 2019. At the

How AI is conducting the future of music technology

“We tend to think of technological advances as destroying what’s gone before, but that doesn’t usually happen. This could lead to a different way of making music.” – Jarvis Cocker, former Pulp frontman, solo artist, writer and broadcaster In recent

Stay up-to-date with Imagination

Sign up to receive the latest news and product updates from Imagination straight to your inbox.

  • This field is for validation purposes and should be left unchanged.