In my disc database I have tick boxes to describe the presentation of the main feature of the disc. These include ‘Pan and Scan’, ‘Widescreen Anamorphic’, ‘Widescreen Non-anamorphic’ and ‘Widescreen cropped’. Pretty much by habit I’ve been ticking the ‘Widescreen Anamorphic’ box for Blu-ray discs, but it has recently occurred to me that Blu-ray discs aren’t anamorphic.<\/p>\n
The word relates to a type of lens used more frequently in the 1950s in the early days of widescreen cinema. The film frames in most cinematographic formats retained the old 1.37:1 aspect ratio, and the obvious way to make them widescreen was just to shoot as usual, but with a mind to masking off the top and bottom of the frame for later cinema presentation.<\/p>\n
However, that wasted a lot of the resolution of the film, so one alternative was to use a special anamorphic lens to distort the picture during photography. This squeezed the picture in sideways so that the widescreen picture could fit into a normal film frame. Then a lens to reverse the process was used at the cinema, stretching the picture sideways, so that its contents were restored to their correct proportions.<\/p>\n
The term was carried over to DVD. The same frame was used both for ‘standard’ TV style video with a 1.33:1 aspect ratio, and for the various widescreen formats. ‘Anamorphic widescreen’ DVDs scaled the picture out sideways to achieve a 1.78:1 aspect ratio. The alternative was letterboxed widescreen, which wasted several tens of per cent of the pixels on the screen, due to the black bars at top and bottom.<\/p>\n
As an aside, even 4:3 DVDs had to be scaled. Most NTSC DVDs were delivered with a picture resolution of 720 by 480 pixels, but for square pixels a horizontal resolution of only 640 pixels was appropriate. For PAL DVDs (720 by 576), a 4:3 picture needed 768 square pixels of display width, so these had to be scaled out in width a little.<\/p>\n
But none of that applies to Blu-ray. The picture is held at 1,920 by 1,080 pixels, which is 16:9 format with square pixels. It is designed to be displayed on a a natively 16:9 display (preferably with a matching number of pixels), so there is no scaling at all. Blu-ray pictures are not anamorphic, even though they are commonly referred to as such on Blu-ray packaging.<\/p>\n
Except for Constant-Image-Height fans. They distort the picture twice at the display stage — once electronically to scale upwards from 2.35:1 to 1.78:1 — and then immediately reverse the process optically with a reverse anamorphic lens which can be swung into place. The purpose of this is, I believe, to replicate the way the picture widens at the cinema for the wider formats. I just don’t like the picture damage this introduces.<\/p>\n","protected":false},"excerpt":{"rendered":"
In my disc database I have tick boxes to describe the presentation of the main feature of the disc. These include ‘Pan and Scan’, ‘Widescreen Anamorphic’, ‘Widescreen Non-anamorphic’ and ‘Widescreen cropped’. Pretty much by habit I’ve been ticking the ‘Widescreen … Continue reading