Blu-Ray is currently the king of physical high-definition media, but there are many kinds of high-definition video available. How does the image quality of Blu-Ray stack up to the competitors?
The Numbers Game
Now that Blu-Ray has won the high-def format war more and more people are upgrading to Blu-Ray. Of course, many consumers are wondering what they're actually getting, and it is easy to see why. Despite an army of marketers across multiple companies, HD video remains highly technical and difficult to understand. And while the HD-DVD at least alluded to the fact that it was a HD media format, the technical quality of the Blu-Ray isn't immediately apparent.
It is, however, quite quantifiable. So let's start cranking through the numbers.
A Moving Target
One problem that still plagues the HD media industry is the fact that the term itself refers to a wide variety of image qualities rather than a specific standard. The Blu-Ray standard is capable of displaying an image of up to 1080p. This is the highest HD resolution currently available, and it looks extremely sharp. That said, HD-DVDs were extremely similar to Blu-Ray in terms of the resolutions the standard supported, and they also supported use of 1080p. 1080p is also vastly superior to the maximum resolution available on a DVD, which was 720x480 in North America.
Now that Blu-Ray has become dominant as the physical media of choice, it is also having to compete with streaming HD and downloadable HD content. The 1080p resolution found on most Blu-Ray discs is generally superior to streaming HD, but this may not always be the case. An HD video which is being watched online will often change its resolution dynamically.
The Compression Question
While resolution is important in determining how good an HD video will appear, there is far more to the equation. HD media is almost always compressed in some way, no matter if the video is on a disc, streamed online, or coming in via a cable company. These forms of compression are usually termed codecs. Compression can cause problems with image quality, such as distortion of color and the appearance of artifacts. Generally speaking, increasing the compression lowers image quality.
This is where Blu-Ray has an advantage to many other forms of HD video. Because Blu-Ray is a physical media generally played using a dedicated player, it is less likely that performance bottlenecks will become an issue. While one might see a sudden loss of video quality while watching online HD video and downloading a large file, such a situation will not occur with a Blu-Ray disc. Blu-Ray discs also have up to 50GB of storage, which is an extremely large amount. This helps ensure that minimal compression is required.
The HDTV Bottleneck
There is one last thing to consider when discussing HD video quality, and that is the resolution supported by the device the video is being displayed on. While many of today's HDTVs support 1080p, there are plenty that do not. Computer monitors are also often used to watch HD video, and the resolutions supported by monitors vary greatly.
Obviously, it is impossible to view a video at a resolution higher than what the display device can support, so those who do not have an HDTV or monitor capable of 1080p will want to note this when considering the image quality of Blu-Ray. This is not to say that Blu-Ray won't work on devices with lower resolutions, however, because the image can be scaled down to the appropriate resolution in numerous ways.
The Final Word
Overall, Blu-Ray image quality is the best on offer right now. The large space available on the Blu-Ray disc minimizes compression and results in clearer image quality, and almost all Blu-Ray movies use the maximum resolution available to the format. While broadcast HD and online HD content have certain advantages, they are slightly inferior and probably will remain so for years to come. That said, the difference can be rather subjective, and those who are not overly concerned with image quality may not notice much of a gap between Blu-Ray and other forms of HD media.