This page contains some basic information to help you understand some of the terms used in the reviews on this site.
Ringing – Often associated with edge enhancement. Ringing on Blu Ray happens when the material is low pass filtered which results in the very finest possible details being lost. Ideally speaking you do not want your Blu Ray movie material to be low pass filtered. Ringing can also occur when a film has been downconverted from a higher resolution.
Edge enhancement – This is a sharpening tool which is often used for the DVD format to give the perception of increased detail. Excessive edge enhancement should never be used on high definition content as it results in very unpleasant image quality and introduces problematic things such as halo's around buildings and people. Click here for an edge enhancement guide with images.
If you have a smaller television set you may not complain too much about this process but once you buy a larger set and start to notice it then you will become very angry and annoyed at the results as it truly ruins the movie viewing experience. The usual reason for too much edge enhancement on Blu Ray is due to old masters created for the DVD edition still being used for the Blu Ray version.
Macroblocking - This often occurs when there is not enough bandwidth allocated to encode very fine detail. The image may break up into blurry blocks during rapid scene changes or pixellate badly. Not seen that often on Blu Ray but an issue with many titles on the DVD format and a very bad issue with low bitrate satellite channels.
HDMI – HDMI stands for high definition multimedia interface and is the digital standard for connecting HD devices, displays and components, and provides for the pristine transmission of high-definition digital video and digital audio via a single cable. HDMI carries uncompressed high-definition video and uncompressed multi-channel audio. HDMI 1.4 is coming in 2010 and will allow for special 3D content to be played back through compatible equipment.
Film Grain – High definition means that for the very first time we have a format that is capable of reproducing the cinema look in your home. This look also includes film grain. Modern films can sometimes look very smooth and detailed due to the fact advances in film stock mean the grain structure is practically invisible to the naked eye or is light in nature and hardly noticeable.
Films from the 1930's and upwards could still have a finer grain look about them due to the fact some productions used superb film stock and may have used more advanced and costly technicolour processes ( as just one example ) of course through time, studio's and film makers got cheap and film grain did became more prominent, films with optical effects sequences may also have more grain but thats due to other factors and not cheaper film stock.
Films may have a very visible onscreen grain structure that people often mistake as noise. This is incorrect. Grain is not noise and in fact makes up the images you are viewing using metal silver hallide particles that interact with photons to form the image.
The grain that some people complain about is in fact the very thing that allows an image to be formed in the first place. Indeed grain will usually be more prominent in night photography than daytime photography. Try using your camera in a dark place and you will notice the image is more noisy ( if digital ) or more grainy if using a 35mm camera.
Grain in films should be preserved otherwise you will destroy the fine detail present in the image.
Many people often have their television monitors set up incorrectly with regards their sharpness or contrast controls. If those controls are set too high it can make grain more prominent and lead some people to believe there are issues with the disc they are watching.
The sharpness control should be set very low when watching high definition material and a calibration disc such as Spears and Munsil or Avia is recommended to set the controls on your television or projector correctly.
DNR – DNR stands for digital noise reduction. It is used to eradicate grain and to make the image you are watching look smoother. The side effects of using DNR on Blu Ray releases is that when you eradicate the grain structure you also destroy the very finest possible detail that high definition is all about and thus it really is a process that should be avoided.
There are other issues that can arise when DNR is used on Blu Ray releases. Not only is detail affected but you can end up with frozen grain in the backgrounds which looks plain ugly. You can have trailing motion artifacts and unnatural waxy looking faces all due to the overuse of DNR. Even when DNR is used sparingly it still removes some detail.
Scratch Removal Tools – The studio's who release Blu Ray content sometimes use scratch removal tools to eliminate small specks or hairs on the print. If handled correctly the results can be excellent but too often you will find a studio goes cheap and decides to be lazy and run an automated scratch removal on the print. Automated scratch removal can sometimes lead to serious issues, for Gone With The Wind, which was done manually, a technician working on the film tells of how the software would keep mistaking an intentionally shot glint in Scarlett's eye as an issue and tried to erase it, luckily Warner checked every frame of the film and kept such details intact, many films are not so lucky and use the automated process rather than manual.
Examples of serious issues on Blu Ray due to automated scratch removal include the removal of bullets, spears, fireballs and even the removal of parts of a person's body or in the case of some animated titles the removal of parts of the hand drawn animation.