IAFilm Productions

Independent Alternative Film
  Home > 7. Article Archives > WhatsUpFilmDigi.htm
 iafilm.co.nz Home

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
You may quote and use on condition that you attribute John Calder as the source of this info.

 


What's up with Film Digitisation?

 

by John Calder

 

In the 1980s, John Calder was a  champion of New Zealand Indie Super-8, making 4 x Super-8 features and a legion of shorts.   His later "indie" movies are shot on "Hi-8" and "Mini-DV".  Day jobs have included commercial film production management, teaching, computer programming and truck driving.  His day job now is teaching computer multimedia and programming at "MITCIT.NZ". (Manukau Institute of Technology). He is currently experimenting with (a) animation using digital stills cameras, (b) digitising his 1980's legacy
and (c) doing High Definition movies by shooting on film then digitising. 
This article is about (b) and (c).

 

The Issues

  1. Digitising the legacy - there must be a quality loss on copying, but lets have some actual measurements on how much loss with different methods and what we need to do to get a high quality result - I will aim for the copy retaining 90% or more of the line resolution of the original.
  2. "Indie" Film-making now - Standard Definition Digital Video (Mini-DV) is very accessible but not quite good enough for what I want to do.  I want to do "greenscreen" effects shots and DV's low resolution colorspace tends to plant green edges around our foreground objects.  I head to the cinema to see "indie" movies shot in DV and react with "almost good enough resolution but not quite".  The introduction of lower-cost High Definition cameras raises a challenge.  Pour money into an early generation of new technology?  Or shoot with dear old film and digitise that?  And which film - Super-8 or 16mm?

 

 

Why build my own digitiser?

 

I want creative control, sometimes down to customising individual shots and even individual frames.  Also I have an idea on how I can do a high quality job = automate the taking of an individual photograph of each frame with a digital stills camera.  And I want to make this kind of digitisation affordable.  There are film industry processes based on individual photographs of frames, but they are very expensive.

 

Main points of the machine.

                Built around a gate+claw from a dual gauge Super-8 + Standard-8 projector.

                Runs very slowly on a geared down motor.  Takes 6 secs between frames because that is how long the digital stills camera takes to take and store a shot.

                Straight-through path with no sprockets is kind to damaged archival film.

                Uses mid-range Olympus Camedia 750 camera.  Uses a lens from a 35mm stills camera as a close-up lens.

                Automatic run achieved by a Microswitch triggered by the gate motor which fires an adapted infrared remote.

 


Test film.

I shot Super-8mm black and white film of a standard EIA1956 line resolution chart.  The film stock, Kodak Plus-X Reversal asa40 is one I could process myself to get an immediate result. 

 

How good is Super-8mm ?

Looking at the result under a microscope gives an EIA1956 result of 600 line pairs both horizontally and vertically.  This compares well with the best of SD video at 540 horizontally and about 450 vertically.

 

With this indication of Super-8 being about 10 per cent better than SD video (720 pixels wide) then I will suggest that Super-8 is roughly equivalent to a digital imaging medium of 800 x 600 pixels.

 

Fig 1:  My EIA1956 result from Super-8mm.

 

Fig 2:  FOR COMPARISON - EIA1956 result from a Sony DCR-TRV950 3-chip DV video camera.  This is generally regarded as a result of "540".

 


Quality of a digitised copy.

The "guts" of this investigation.  What happens when we digitise film at various copy resolutions?  I first tried to checked this out by using the Olympus zoom lens to vary my photos of the Super-8 image.

 

Fig 3:  First Test method (representative 4 images)

 

BUT the zoom-out results were lower than previous tests I had done with video cameras.  On double-checking by taking full-frame shots while changing resolution with the camera controls, I got higher resolution results.

This opens another interesting question which I will ask by example. 

To get a final result of 720 x 576 do we shoot an image of that size first-off?..
OR is there any benefit to shooting a higher-resolution image first off then downsizing later in the computer?    I come to this expecting that it should make no difference, but this first bad result makes me re-think!

 

I therefore took my final set of measurements full-frame at varous resolutions and used a little zoom-out - approx equivalent to the first image above - to get some in-between settings.  Note that the EIA1956 resolution reading is a rather subjective art.  Figs 1 and 2 show that well.

 

The stills camera, an Olympus Camedia UZ750, offers 2 quality settings for jpg compression "High" and "Normal".  Trying both, I found they made no difference for shooting at 1280 x 960 and above.  But below 1280 the "High" showed up as delivering an advantage.   The graph shows the "High" settings with one "rogue" point for 720 x 576 coming from a different setup using a video camera.

 

Results

ImageID

Copy Image Width

Copy JPG

Setting

RES

File Size (KB)

Notes

2

2288

HI

600

2723

  

3

2048

HI

600

1534

  

4

1600

HI

600

1058

  

5

1280

HI

600

754

  

B5

1280

NORM

600

272

Economy file size works well here

6

1024

HI

570

498

  

7

1024

NORM

550

164

Economy quality loss effect appears

10

844

HI

550

394

  

VidCam

720

DV

430

160

  

8

640

HI

520

184

  

9

540

HI

430

181

  

 


 

I see enough of a pattern here to suggest a "rule of thumb".

 

IF there is a difference between the Resolution of the Original and the Resolution of the Digitising Method

THEN - the Copy inherits the lower Resolution of the 2

 

ie "A chain is as strong as its weakest link"!

 

ELSE - IF the Original and the Digitising method are similar in Resolution

THEN - the Copy is of reduced Resolution, by between 10 and 30 per cent - but we need to investigate more.

 

 

The results are better, and this rule is more optimistic, than what I was expecting from my past studies of maths and physics formulas.   Although this may fit the "Nyquist-Shannon Sampling Theorem" (Wikipedia, 2006, 1) if anyone could come up with a meaningful definition of the "bandwidth" of Super-8.

 

The greatest uncertainty happens in the "ELSE" zone, which is where one of my biggest questions lies = what reasonable final result can we expect from copying Super-8 to Standard Definition TV? (720 x 576).

 

My answer is to come up with a reasonable workflow to produce the common DV flavour of SDTV then look at the resolution.

For copying on my machine with the Olympus Still Camera, I see that the best "bang for my buck", ie smallest file size giving a 600 res result, comes at 1280 x 960 with the "NORMAL" (ie low) jpg setting.  Files are about 270KB each which means I would usually be able to fit 1 x 50foot Super-8 roll on 1 x 1 Gig memory card.  This has a lot of practical appeal because it means transferring those common rolls in one unattended automatic run without needing a stop for a change of card.

 

So to get 720 x 576 PAL,  or the NTSC 720 x 480, the workflow that appeals is to shoot at 1280 x 720 then process to 720 x 576. Lets do it and see what happens�


The resolution is fairly good at about 470.  You can see how tricky it gets judging that point where we lose the distinctiveness of the lines, and it seems to be especially hard in this "ELSE" area of approx matching resolutions.  I could argue for results from anywhere in the range 430 to 500.

But Ouch! the "aliasing" effect is a bit of a worry!  Look at the staircasing on those diagonal lines!  I need to rethink my workflow idea.

 

I applied 3 video processing filters to my upside-down negative original.: 
"Flip - Vertical", "Invert" (turning a negative to a positive image), and "Brightness/Contrast" (it is normal for raw negatives to be low contrast and I need to increase the contrast in further processing)

Retain "Flip" only to keep it readable, and the result is STILL BAD ..

 

"Flip" etc are provided by a Video Editing Program, "ULead MediaStudio Pro version 7".  This is an old version of ULead, so to be fair I try again, downloading the trial version of their current Version 8.  VERSION 8 WORKS OK but I know my boss won't buy it because video editing is only a small part of our work and his budget is tight this year.

 

I look for an open source or low cost answer.


Next Experiment:  Try a different "Flip" - this is the one provided by "The GIMP version 2.2.10".  Looks like "The GIMP" does a good "Flip".

 

And here is the makings of a workflow.  Fortunately "The GIMP" is scriptable in that it can consistently "Flip" collections of images on demand.

 

Lets try again.  New workflow.

1.  Work in "The GIMP" at 1280 x 660 to process the image(s)

2.  Then load results into the Video Editor to downrez and process to SDTV.

Result:

 

 

Form your own opinion, but I am going to declare at 470

 

First interesting "indie" conclusion:

Prediction of what happens to film copied to SDTV

Super-8mm                 470

16mm                          540  (lesser of the 2 media delivers its maximum)

Super-16                     540

35mm+                       540

Armed with this result, I now try to improve my math model graph.

I replace the (720,430) point with this new (720, 470) result then overlay some lines to represent the rule-of-thumb, with major weighting given to the hard-earned (720, 470).

 

 

The Cusp (point of max correction factor) happens at (800,500)

The Original and Copying-Method resolution are both 600.  The expected resolution is 500 which is 83%.  This is the maximum correction factor.

I now try to predict other film format calculations by re-scaling the Cusp to
(100, 83) so I can apply this as as percentages of any film digitising scenario�

To predict the behaviour of 16mm, I will first need to find its line resolution.


 Practical Experimentation with "Simulated 16mm"

I know that 16mm is bigger and better than Super-8mm.  But I want to know HOW MUCH better with this digitisation workflow?

 

Shooting 16mm tests with fresh film stock was out of the question for this investigation because of the cost.  The minimum quantity I could buy and process was 10 mins costing NZ$350 to do the test.

 

What I did instead was to shoot tests with a 35mm Stills camera, aiming to frame so that the charts and other test shots occupied a space of about 10mm x 7mm.

I then cut 16mm wide strips out of the processed negatives and placed them in a projector gate to photograph.

 

I used consumer Fujicolor film rated at asa 200.

 

My frame sizing did not hit the mark.  The chart read about 560 but appeared about 2/3 the size of the projector gate it was sited in.  Applying a correction for that SUGGESTs an EIA1956 resolution rating of 830 for Standard-16mm at 200asa.

 

So that is

600 - for Super-8mm

830 - for Standard-16mm (but with a more flexible film stock)

 

I will now do a wild guess for the effect of a finer-grain film and suggest

the following EIA1956 resolution rating summary.

600 - for Super-8mm

900 - for Standard-16mm at 100asa

1080 - for Super-16mm at 100asa

 

What is this in Pixels?  Now getting very approximate, and it will vary a lot with different film stocks, but I am going to regard 16mm as follows:

Standard-16mm - 1200 x 900

Super-16mm   - 1500 x 900

 

This suggests that even Standard-16mm can hold its head high as a genuine High Definition Digital Television format.


But what is going to happen to 16mm on digital copying and HDTV projection?

I now look to the generalised graph for answers.

 

Listed below are my predictions for the various fates of Super-8mm, Standard-16mm and Super-16mm.  Units are EIA1956 line resolution.  See Appendix One for the math detail.

HDTV-720 is the 1280 x 720 medium.
HDTV-1080 is the full 1920 x 1080 medium just emerging as of early 2006.
I have not included HDV which is an intermediate 1440 x 1080 anamorphic medium rescaled to 1920 x 1080 for viewing.

By "HDTV" I mean a large TV or video projector wired to the playback machine
ie "Closed Circuit" as in a film festival scenario, without quality losses due to broadcast.

 

Appendix One gives the details of how I use the graph to get these values.

 

Super-8mm (without cropping, appears with black side bars on 16:9)

Original                        600

SDTV                          470

HDTV-720                   540

HDTV-1080                 600

 

Standard-16mm (without cropping, appears with black side bars on 16:9)

Original                        900     

SDTV                          540     

HDTV-720                   650     

HDTV-1080                 810     

 

Standard-16mm - cropped to 16:9 for HDTV.  The horizontal rez calculations give higher values but the loss in vertical resolution probably results in a human perception of about the same resolution as the 4:3 display.

Original                        900     

SDTV                          540

HDTV-720                   760      (650)

HDTV-1080                 900      (810)

 

Super-16mm - cropped slightly to 16:9

Original                        1080

SDTV                          540

HDTV-720                   840     

HDTV-1080                 990                 

 

Based on this I now draw some conclusions to guide me and my friends in our own film-making.  16mm conclusions first and I wrap up
with my beloved Super-8mm

(It is up to you how much weight you give to my test methods and indie point of view!)      


 

Standard-16mm makes good sense from where I stand as the entry path into High Definition Digital Moviemaking.  The cost of film and processing competes well with buying or hiring HD Video Cameras for the next 10-minute movie I have lined up.  Within my "indie" subculture there are good Standard-16mm cameras available.  My likely crew of fellow 50-somethings dragged kicking and screaming out of suburbia to relive their hippie alternative cinema youth, are well skilled in 16mm.  Like all film options, the digitisation workflow is going to make post production far nicer than we had it in the 1980s.

 

Super-16mm.  I do not have access to this.  One friend has toyed with the idea of converting a camera, probably at a cost of NZ$1000.  My advice to him will be "don't bother, spend the money on film stock and get on with it, Standard-16mm rocks for what we want to do".  To make 16mm go in my "indie" subculture, part of the make-it-affordable equation will be DIY digitisation via home-made machinery, and this will be much easier for Standard-16mm.  I can temporarily alter the light source in a borrowed 16mm projector and run it with a strapped-on car windscreen-wiper motor, but hacking at the gate with a file would be a no-no!

 

For those working with a higher level, Super-16mm makes a lot of sense.  Wikipedia states under "16 mm Film":
"Some low-budget theatrical features are shot on Super-16; ironically, thanks to advances in digital technology - specifically digital intermediate (DI) - the format now seems to be seen as revitalized option." - (Wikipedia, 2006, 2)

 

 


Should I make new movies with Super-8mm?

Should You make new movies with Super-8mm?

 

The Super-8 frame is 5.3mm wide

The Standard-16mm frame is about 10mm wide

The Super-16mm frame is about 12mm wide.

 

My results suggest that Standard-16mm, although twice as big as Super-8mm, has only about 1.5 times the resolution, mainly because of the common use for 16mm of more sensitive film stocks of lower resolution.  I suggest that
Super-8mm "punches above its weight" but as a cheeky Super-8 film-maker from way back I would enjoy stating that.  Some more evidence would be nice.

 

On Sept 17th 1985 I produced Colin Rock's script "Do It With a Real Fox" in 16mm but also with some Super-8.  I have found closely matching shots of performer Linc Mail from the 2 cameras and put them through my digitising process.  Here they are!  Printed equal frame height - cropped narrower to fit side by side.

 

Guessing game - which is Super-8mm and which is 16mm?  The Answer is revealed at the end of this article!

 

 

 

I will almost certainly make at least 1 new Super-8mm short film to explore the option.  But it will be with subject matter, an offbeat short fantasy drama, where the artistic quality of grainy texture will work for the story.  I'll be doing this mostly for the nostalgia revisit.  I want the experience of working with a Super-8 where many of its classical handicaps are gone but the fun remains.

I've kept the cameras and the processing tank all these years, gotta do something with them.  With Kodak's new Super-8 Ektachrome 64T film to try out, full computer post-production power, and effective projection commonly available at film festivals, that could be a very interesting something.

 

 

Should YOU make new movies with Super-8mm?

My message to most young emerging film-makers would be "no".  Resist the "retro romance" reputation given to Super-8mm by some avant-garde artists and take your own good hard look at it.  Use it only if you want that particular "look" or if the most easily available and most-liked camera for you is a Super-8.  When I do Super-8mm, I know that in terms of conventional ideas of image quality, I  will be below the edge that 16mm can give me at about half the price.  If you are paying for transfer to video, the price gap will narrow.  16mm will then give genuine high definition at about only about 30 percent greater cost than Super-8mm.

 

My Super-8 rez results are higher than what I expected, but come in the range of "almost good enough to compete, but not quite".

 

Another warning to the romantics- beware the gate-registration curse of Super-8mm.

The easy-load cartridge has film transport disadvantages which can show up as vertical jiggling of the image.  This varies a lot with cameras and conditions.  During these tests, my steadiest results came from a Canon 814E.

But note that 16mm may mean in practice using cameras over 50 years old, and that also means a risk of jiggle ("poor gate registration").

 

Test well if you can.  I have!

Follow-up - June 2007
Since writing this article I have produced a new Super-8 film, "Love Song to Super-8", partly to try out Kodak's new Ektachrome 64 film stock.  Some new information:  I found this colour stock gave me very grainy results. It suited this particular movie but it also delivered less resolution than the black and white film used for the tests reported on above. My updated opinion is that Super-8 can deliver high definition results but ONLY with fine grain black and white film eg Kodak 7276, Kodak 7265. Otherwise my conclusions and warnings remain the same as above.  Even the mighty 16mm is increasingly under threat from affordable Hi-Def Video with the new Canon HV20 Camera looking like an excellent breakthrough tool for no-budget indies.

 

How best to archive Super-8?

I have my own answer.  Digital Still Photos at 1280 x 960 pixels.

 

There has been vigorous debate on whether owners of real-time condenser lens systems should upgrade their video cameras to high definition. eg Sony FX1, Canon XL-HD1.

 

"I have about 4 hours of super 8 video, flimed in the seventies and eighties. Some of the movies we brought to a "professional" transfer to DVD service but the results were not very good.

My wife was just about to bring them to another shop, but then I said, let's use the HDR-FX1 and find out about the quality of the transfer. No telecine device was used. Just an old Elmo Super 8 projector onto a 2 feet diagonal screen. FX1 was on HD, filming directly off the screen.

What did we get? Stunning results! I was afraid first about strobing effects due to the 24 fps projector speed and the 60i recording. But there was practically no strobing. So far the best transfer of Super 8 movies I have ever seen."

Internet Discussion: Author alias "hptschupp", (sonyhdvinfo.com, 2005)

 

"the resolution of Super 8 is too low in my opinion to benefit from HD"

Response to above: Author alias "cprogrammer", (sonyhdvinfo.com, 2005)

 

I suggest that it is indeed worthwhile to use HDV cameras like the FX1.

Super-8 original capability

 

600

Copy with SDTV camera - "480i" or "576i"

 

430 - 470

Predicted result with HDV camera - "1080i"

 

570

 


Appendix  One:

 

The summary table in full.  More details on where those numbers come from.

 

Super-8mm (without cropping, appears with black side bars on 16:9)

Original                        600      -  from direct experiment as above

SDTV                          470      -  from direct experiment as above

HDTV-720                   540      -  960 pixels 120% 90% x 600

HDTV-1080                 600      -  1440 pixels is in the 1280-and-over range

 

 

Standard-16mm (without cropping, appears with black side bars on 16:9)

Original                        900      -  experiment as above (830)  with estimated
                                                    correction for finer grained film.

SDTV                          540      -  expect full SDTV performance

HDTV-720                   650      -  960 pixels 80% 72% x 900

HDTV-1080                 810      -  1440 pixels 120% 90% x 900

 

 

Standard-16mm - cropped to 16:9 and therefore using full horizontal width
(but it loses some vertical resolution, note these values are horizontal res only)

Original                        900     

SDTV                          540

HDTV-720                   760      -  1280 pixels 106% 84% x 900

HDTV-1080                 900      -  1920 pixels 160% 100% x 900

 

 

Super-16mm - cropped slightly to 16:9

Original                        1080

SDTV                          540

HDTV-720                   840      -  1280 pixels 85% 78% x 1080

HDTV-1080                 990      -  1920 pixels 128% 92% x 1080


Reference List

 

 

Wikipedia, 2006, 1.  "Nyquist-Shannon Sampling Theorem", Wikipedia On-Line Encylopaedia Website.  Retrieved 30 Apr 2006 from
http://en.wikipedia.org/wiki/Nyquist-Shannon_sampling_theorem

 

Wikipedia, 2006, 2 "16 mm Film", Wikipedia On-line Encylopaedia Website.  ,  Retrieved 30 Apr 2006 from
http://en.wikipedia.org/wiki/16mm_film

 

SonyHDVInfo.com, 2005, "Super-8 to Video Project", SonyHDVInfo Discussion Groups.  Retrieved 30 Apr 2006 from

http://www.sonyhdvinfo.com/showthread.php?t=3588&highlight=Super-8mm

 

 

 

 


Guessing Game Answer

Super-8 on the LEFT, 16mm on the RIGHT.

Super-8 is Agfa Moviechrome asa40, camera is Sanyo XL600

16mm is Kodak Ektachrome Video News Film asa125, camera is Bolex H16R

 


 iafilm.co.nz Home

Creative Commons LicenseThis work is licensed under a Creative Commons Attribution 2.5 License.