Spearhead from Space - Blu-ray

As the only classic Doctor Who story to be shot entirely on film, Jon Pertwee's debut story provides a unique opportunity to present the series in high definition via Blu-ray.

It's only by an accident of fate that Jon Pertwee's first story was made on film at all. Industrial action meant that the studios at Television Centre were not available, so the decision was made to shoot the story entirely on location using 16mm film cameras. The existing cut camera negatives were retained to this day in the BBC archive, giving us the potential to go back to the very best quality source for this Blu-ray release.

 We have, of course, worked on Spearhead three times before - once from print for a BBC2 transmission in 1999, an upgrade of that master for the initial DVD release in 2000 and again from newly struck interpos in 2011 for the Special Edition release as part of the Mannequin Mania boxset. Readers may find it useful to read through these three articles first for background.

As noted in the later article, we did transfer the interpos in HD in 2011 for potential future Blu-ray use. However, in the intervening couple of years, the grading team at BBC Studios & Post Production had brought in new tools and developed workflows to allow them to work economically from the AB-roll cut negatives directly. Essentially this involved scanning the films and digitally correcting the jumps and other positional disturbances caused by splices before resizing and grading.

The cost of working from the original negatives was obviously much higher than simply working from the HDCAM-SR transfer of the interpos, but an agreement was reached to allow this to happen. Because of the large amounts of data involved (each episode is around 450GB), it was decided that it was quickest and most cost-effective to keep the entire process in-house on the enormous storage SAN at S&PP rather than to pass the picture cleanup out to SVS as usual. The soundtrack had already been remastered for the previous DVD release so no further work was required from Mark Ayres.

Work began by ultrasonic cleaning of the 16mm cut negatives, comprising two circa 950ft rolls per episode. Each roll was then scanned at 2K to 10-bit RGB DPX frames using a DFT Scanity film scanner. The episodes were then digitally reconformed by colourist Jonathan Wood from the two rolls onto a single timeline on a Digital Vision Film Master non-linear grading system, using the previous DVD release's Digibeta master as a reference. Film Master which was also used to stabilise the splice instability before resizing the image to create a 4:3 image pillarboxed into the 1920 x 1080 pixel HD frame. Jonathan  monitored his grade on a 42" Dolby PRM-4200 professional reference monitor, fast becoming the industry standard monitor since the demise of the CRT. Having spent the previous three months grading the seventies cop show 'The Sweeney' for Network's excellent Blu-ray release, Jonathan decided to apply some of that look to 'Spearhead', giving this new transfer a more realistic 'drama' feel than the previous release.

Film Master grading suite

During scanning, it was noticed that both rolls of episode three were covered in blemishes which were not apparent on the transfer from the interpos. Inspection of the film showed white marks all over the surface of the film. The conclusion reached was that at some point in the past, episode three had been given a surface lacquer coating, probably to fill scratches on the acetate film base. After peeling off several layers of labels on the cans, a label for a process called PermaGuard was discovered. It seems that the lacquer has chemically reacted with the wetgate solvent used in the optical printer when the films were in the lab to make the interpos in 2011. Closer inspection of the HDCAM-SR transfer of the interpos showed that the solvent was actually becoming polluted as the printing process progressed, with occasional flurries of blemishes appearing. The films have been passed to the film examiners at the BBC archives for assessment of the best way to remove the markings to preserve the negatives for future use. The new interpos had been put into the archive anyway, so there  are good physical and digital backups of this episode available. We decided to use the interpos transfer of episode three as the master for this release.

Post-grade, the episodes were passed onto Amanda Whitby and Sheona Henderson for manual cleanup of dirt, sparkle and other blemishes using Diamant Dustbuster +, before being returned to Jonathan for more targeted shot-by-shot grain management and tweaks to the grading as required during the client viewing session with the Restoration Team's Steve Roberts.

Below is a comparison of the picture quality differences between the Blu-ray and the DVD. The picture represents one quarter of the HD frame, with the Blu-ray grab presented here pixel for pixel compared against the DVD grab upscaled to HD. The geometric differences are due to differences in scanning on the two transfers. Roll the mouse over to reveal the DVD version. Grabs by Alex Lydiate, with thanks.

As noted in the article for the 2011 DVD release, there are two points in the story where frames are missing, possibly due to neg cutting errors in 1970. These had been fixed at standard definition by Peter Crocker, who created new motion-estimated frames to bridge the gap. With no budget to do this again at HD, Jonathan upscaled the SD fixes, matched the position and the grade, grain and sharpness to his HD material and dropped them into his timeline. As both are short shots on rapid movement, the inclusion of SD-sourced material isn't noticeable.

'Spearhead' was originally shot and edited at 25fps, as befits a UK television production, so was remastered at 25 progressive frames per second, or 25P as it is known colloquially. However, the Blu-ray standard doesn't include 25P, so it is presented on Blu-ray at 50i (50 interlaced fields per second), which is the norm for this sort of material. As both fields originate from the same point in time (ie the same film frame), there is no real difference between 50i and 25P in this case.

For the US release, the choice was more complicated. In order to maintain the same running time, the 25P master would have to be standards converted to 59.94i, which would create inherent conversion artefacts as well as potentially introducing other artefacts caused by deinterlacers and scalers in the consumer's player and TV. It was therefore decided that the best way of presenting the show for the US disc in order to optimise the quality was to slow it down to 23.98fps (which is generally referred to as 24P, although that term covers both 23.98 and true 24.00fps rates - 23.98 being the most generally compatible due to its strong relationship to the 59.94 field per second video standard). This maintains the 'one video frame for every film frame' link which means no deinterlacing issues, but it does mean that the soundtrack is also running around 4% slower than normal. This is somewhat mitigated by digitally pitch correcting the audio so that voices appear to be at the normal pitch although speech itself is still slightly slower. This pitch correction was done downstream of us by authoring house Deluxe, using Avid Protools.

One audio change has been made compared to the last DVD release, which is to reinstate the original stuttering TARDIS materialisation noise at the beginning of the first episode.

The decision was made by 2entertain that this Blu-ray release was to be a companion disc to the DVD included in the Mannequin Mania boxset rather than a replacement for it, so none of the additional features from that DVD have been included here. Instead, a package of brand-new HD extras was put together to compliment the main feature.


Disc Contents:

• 4x 25 mins approx colour episodes with mono audio.

A Dandy and a Clown (dur. 42’ 19”) – this exclusive documentary looks at the life and career of Jon Pertwee. With contributions from actors Katy Manning, Judy Cornwell, David Jacobs, Geoffrey Bayldon and Kenneth Earle, Doctor Who writer and script editor Terrance Dicks and long-time friend Stuart Money.

Carry On: The Life of Caroline John (dur. 29’ 07”) – a tribute to the actress who played the part of the Third Doctor’s assistant in his first season. With husband Geoffrey Beevers, daughter Daisy Ashford, brother Seb John, sister Priscilla John and friends Jennie Heslewood and Patricia Merrick.

Title Sequence Material (dur. 22’ 38” ) – raw, mute test and build-up material produced during creation of the Jon Pertwee title sequence.

Restoration Comparison (dur. 2’ 13” ) – this release was mastered in 2K from the original 16mm camera negatives and interpos prints for the best possible quality. This short feature compares the results against previous versions and looks at some of the problems encountered during the remastering.


Copyright Steve Roberts, 4 July 2013. No reproduction allowed without written permission.