Black-screen & White-screen: The Best Kept Secrets in Compositing

Accessing the compositing modes in Final Cut Pro 7
Accessing the compositing modes in Final Cut Pro 7

When it comes to shooting elements for VFX, green-screen gets all the press. But certain kinds of elements can be tricky to key well, and sometimes it’s not the right look. In the last few days Kate Madison and I have needed to shoot last-minute elements for some shots in Ren: The Girl with the Mark, and we turned to monochromatic backgrounds.

Why? How does it work? Well certainly you can key out black or white just like you’d key out green, but the most powerful way to use these backgrounds is not with keying at all, but by a bit of basic maths. And don’t worry, the computer does the maths for you.

If you’ve ever used Photoshop, you’ll have noticed some layer modes called Screen and Multiply. Final Cut Pro has the same modes (it also has Add, which to most intents and purposes is the same as Screen) and so do all the major editing and FX packages.

Screen adds the brightness of each pixel of the layer to the layer underneath. Since black has a brightness of zero, your black screen disappears, and the element in front of it is blended seamlessly into the background image, with its apparent solidity determined by its brightness.

Multiply, as the name suggests, multiplies the brightness of each pixel with the layer underneath. Since white has a brightness of one, and any number multiplied by one is that same number, your white screen vanishes. Whatever element is in front of your screen is blended into the background image, with darker parts of the element showing up more than lighter parts.

One of the elements Kate and I needed to shoot was a flame, to be comped onto a torch. We lit a torch and clamped it to a stand, shooting at night with the pitch black garden in the background. It was the work of moments to comp this element into the shot using Screen mode.

The flame element, shot at night in the garden to ensure a seamless black background
The flame element, shot at night in the garden to ensure a seamless black background
I adjusted the flame's size and used Screen mode to composite it over the background.
I adjusted the flame’s size and used Screen mode to composite it over the background.

Fire is the perfect partner for black-screen shooting, because it generates its own light and it’s not solid. Solid objects composited using Screen/Add or Multiply take on a ghostly appearance – perfect for, er, ghost effects – but not ideal in other situations; because of the way Screen mode works, anything that’s not peak white will be transparent to some degree.

We shot some fast-moving leaves and debris against black, but only the high level of motion blur allowed us to get away with it. In fact, if you know you’re going to have a lot of motion blur, black-screen might be the ideal method, because it will be tricky to get a clean key off a green-screen.

A smoke element shot against a black drape and backlit so that the smoke is visible but the drape is not
A smoke element shot against a black drape and backlit so that the smoke is visible but the drape is not
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Shooting dirt in a vase of water against white

Other things that work well against black-screen are sparks, smoke and water/rain, again because they’re not solid. If you want to add rain or snow to a shot, black-screen is the way to go – check out my post about that here.

Yesterday Kate and I needed to shoot a whirlwind element. One of the VFX team suggested swirling sand in a vase of water. After a few experiments in the kitchen, we ended up using dirt from the garden. We used fluorescent softboxes for the background, ensuring we got a bright white background, and made weird arrangements of white paper to eliminate as many of the dark reflections in the vase as we could.

One of the tornado elements shot with the set-up pictured above. We let the dirt settle in the bottom of the water, then swirled the water with a spoon (which had to kept out of frame).
One of the tornado elements shot with the set-up pictured above. We let the dirt settle in the bottom of the water, then swirled the water with a spoon (which had to be kept out of frame).

A few weeks back we shot hosepipe water against black, inverted it and used Multiply to superimpose it as blowing dirt.

With a little thinking outside the box, you can shoot all kinds of elements against white or black to meet your VFX needs. I’ll leave you with this featurette I made in 2006, breaking down the various low-tech FX – many of them black-screen – that I employed on my feature film Soul Searcher.

Black-screen & White-screen: The Best Kept Secrets in Compositing

Review of My Year: 2015

Shooting Ballet Pointe Shoes on an Alexa HD
Shooting Ballet Pointe Shoes, my first time working with an Alexa

Where has the year gone? Can you believe that all of the Back to the Future trilogy is now set in the past? It’s been a great year for me, one of moving in the right direction.

At the end of last year I said, “In 2015 the goal is very simple: keep DPing drama, with a bit of gaffering in the gaps.” And that’s exactly what I’ve done. That and postproduction supervising a web series – but more on that in a minute.

Last year I made the huge but entirely correct decision to stop doing corporates, and that did lead to some gaps in my schedule. 2015 started slowly, with a couple of gaffering jobs on Oliver Park’s short Vicious and John Quarrell’s The Gift.

In late January I reached the milestone of my 1,000th blog post, and published an article looking back at my various film blogs over the years.

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Photo: Laura Radford

Meanwhile, I asked Kate Madison if she needed any help with post on Ren: The Girl With the Mark, the awesome fantasy web series I had DPed for her the previous autumn. By Easter I had cut 30 or 40 behind-the-scenes and production diary videos for the show, become postproduction supervisor for the series and moved into Kate’s spare room! Between the paying jobs this year I’ve overseen the show’s many VFX – even doing several of them myself – created an EPK, organised ADR sessions, appeared on Comic Con panels, and shot hours of interviews for a DVD documentary.

Moving out of Hereford was a much-needed change, although the place treated me well over the years. Cambridge, my new home, is a beautiful city which encourages lots of healthy cycling, and London is much more accessible from here.

Some of the crew rigging lights on Exile Incessant
Some of the crew rigging lights on Exile Incessant

Work picked up as the summer approached. Shorts I’ve cinematographed this year include Gisella Pereira’s fairytale Ballet Pointe Shoes, James Reynolds’ race drama Exile Incessant, Stanislava Buevich’s black comedy Self Control, Douglas Morse’s medieval comedy The Second Shepherds’ Play, and Ben Bloore’s mysterious drama Crossing Paths, plus the period comedy web series pilot Owl House by Mark Keegan. And I was delighted to visit Japan for a few days to shoot pick-ups for a sci-fi feature called Synced, directed by Devon Avery. Most of these projects have blog posts about them, so click the links above to check those out.

But 2015 saved the best for last, with my first paid feature film job coming out of the blue in November, courtesy of a glowing recommendation from sound recordist David Bekkevold. I learnt so much from this project, some of which you can read in the daily blogs I posted, and others of which I’ll be blogging about soon. I now feel like I could walk onto almost any set as a DP and acquit myself reasonably well.

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As 2016 approaches I have an ambitious 30-minute fantasy short booked in for the end of January, and attachments to three features. A lot of my work is now in the period/fantasy arena, which is exactly what I was hoping for after doing The First Musketeer back in 2013. It’s taken sixteen years, but I finally feel like I’m getting there – wherever there is!

As usual, I’ll leave you with my ten favourite blog posts from this year…

  1. Women on Film: Characters or Glorified Props? – an article about misogyny in the movies
  2. Lighting ‘3 Blind Mice’ – demonstrating how backlight and contrast control can help tell the story
  3. Shooting in Rain – practical advice for keeping the camera rolling in a downpour
  4. 20 Facts About the Cinematography of Mad Max: Fury Road – culled from interviews with the DP
  5. How to Correct Cosmetic Issues with Lighting – handy tips for flattering your cast
  6. Synced: The Japan Shoot – Part 3 – how I lit a nighttime street scene in Himeji with a few small units
  7. The First Musketeer: Lighting the Barracks – lighting breakdown for a key action sequence from the period web series
  8. Distribution and the M&E (Music and Effects) Mix – an explanation of how films are dubbed, what materials a producer needs to deliver to a foreign distributor, and a video showing the various stages in creating Soul Searcher’s Japanese dub
  9. Crossing Paths: Day Exterior – revealing how to manipulate the sun to get the best results
  10. Feature Shoot: Day -1 – testing lighting looks and Soft FX filters with the Alexa and Cooke S4s
Review of My Year: 2015

Star Wars Episode VII: The Feminism Awakens (Spoilers)

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J.J. Abrams, though one of my favourite directors, has something of a chequered past when it comes to representing women on screen. Although noted for female leads in some of his projects (the TV shows Felicity, Alias and Fringe), he’s not averse to showing them in their underwear to grab ratings or boost ticket sales. The season four premier of Alias springs to mind – a scene with Jennifer Garner in lingerie was brought to the start of the episode as a flash-forward in a cynical effort to hook audiences – as does the gratuitous shot of Alice Eve in her underwear in Star Trek Into Darkness, which rightly caused an internet furore.

So I waited with mixed feelings to see where Star Wars Episode VII: The Force Awakens would fall on the misogyny/feminism spectrum. BEWARE: SPOILERS AHEAD.

The film presents two new central characters, vying for the position of protagonist: John Boyega’s Finn and Daisy Ridley’s Rey. For the first few reels, the script seems to be trying too hard to be feminist: Rey is constantly rebuffing Finn’s patronising attempts to protect her. This reeks suspiciously of the “post-sexism” portrayal of female characters, whereby they serve the same old plot function of damsel in distress, but are made “strong” by perfunctory attempts to assert their authority and complaints about how reckless and useless the men are – even though the patriarchal script still has those same men save the day.

screen shot 2015-10-19 at 10.31.30 pmThis theory seems to be confirmed as Rey is knocked unconscious and carried off to the villain’s lair, leaving us to assume her plot function is indeed just to be rescued by Finn. Aboard the Death Star, or whatever they’re calling it, villain Kylo Ren creepily remarks that he can take whatever he wants from her. He proceeds to mind-rape her with the Force – a much darker interrogation than Vader’s implied use of the floating spiky ball thing on Leia in episode IV. But the film toys with our expectations as Rey turns this invasion back on Ren, and subsequently escapes her cell through her own agency.

Things get patriarchal again when a climactic light sabre battle sees Rey knocked unconscious as Finn fights the villain. But suddenly J.J. turns the tables. Rey recovers, Finn is knocked unconscious, and Rey triumphantly defeats the antagonist with a bad-ass combination of physical and mental prowess. At least, she defeats him as much as the antagonist can ever be defeated in the first part of a trilogy. Presumably in Episode IX she’ll send him spiralling fatally into the depths of a bottomless shaft, since the whole plot is just a re-run of the original films.

2326134Despite its female protagonist, Episode VII’s feminism is far from perfect. In common with other female leads in contemporary cinema, Rey is surrounded by a sea of male characters, as if the filmmakers have to compensate the audience for the lack of one big leading penis with a plethora of supporting penises. The movie only passes the Bechdel Test by the skin of its teeth, as far as I can recall – Rey’s conversation with Maz Kanata being at least partly about Luke, and dialogue between Rey and Leia not occurring until the film’s closing minutes.

Frequently throughout the running time, Rey is referred to simply as “the girl”. This is a recurring and worrying theme in genre movies: “Give me the girl”, “Let the girl go and I’ll give you the MacGuffin”, etc, etc. Apparently women are so insignificant and interchangeable that they need no names. Let’s hope that J.J. and co-writers Lawrence Kasdan and Michael Arndt were deliberately pastiching this as part of their subversion of gender roles.

Either way, Star Wars Episode VII: The Force Awakens is refreshingly feminist and presents a great female role model. Hopefully there will be just as many little girls wanting light sabre toys as little boys (though I find the lack of Rey action figures disturbing). I doubt we’ll ever see a female Bond  – sleeping with hunky men then not caring when they get killed – but we’re moving closer to a female Doctor Who – two major Timelord characters having recently regenerated into women – and having a woman at the centre of the Star Wars universe is a definite step in the right direction for the world media’s representation of the gender.

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Star Wars Episode VII: The Feminism Awakens (Spoilers)

Heretiks: Day 25

The last day. A splinter unit is in a studio in Swansea shooting a body burn stunt, but I miss that because the main unit are shooting exteriors at Margam. There is heavy rain in the middle of the day and it becomes unsafe to do the chase scene amongst the trees that is scripted. I wander around the castle grounds with Paul, Bali the 1st AD and Mikey from locations in an effort to find somewhere safe but visually suitable in which to re-imagine the scene.
After lunch we find a path in the woods and Paul comes up with a way to stage it all in one dynamic steadicam shot. Rupert shoots it beautifully and as the daylight fades Bali calls a main unit wrap.
Many hugs and goodbyes later, I arrive at the studio to join the splinter unit for their last few hours. They are setting up a wire rig from a cherry-picker against a green screen to shoot FX elements of a creepy girl. While that is being rigged, 2nd unit DP Keefa is getting tight inserts of gory prosthetics on a table nearby, shooting on his Red Dragon and referring to main unit footage on a laptop so he can match my lighting.
Producer Mike asks me to shoot a green screen element of the creepy girl staring while the wire rig is being set up. Rupert and Max arrive with the Alexa and we hook up to the mix and overlay system. This keys out the green in real time and allows us to see the creepy girl against the plate we shot at Margam yesterday. She can’t see the monitor herself so she doesn’t know where she is. I ask her to take two steps to her left. It is EXACTLY like Knightmare. Welcome, watchers of illusion.
Keefa takes over to shoot the wire rig stunt, while I work with Paul to shoot inserts. The art department have recreated little pieces of some of the sets in this cavernous studio space. We also shoot a prosthetic head cast of one of the lead actors having her eyes poked out. Lovely. Then we grab some more green screen elements, including fake blood spraying in various directions. Co-writer and prothestics make-up artist Conal is using a fire extinguisher to spray the blood. It goes everywhere.
We wrap at last, and I’m very glad I got to come along and do this last fun little bit at the studio.
Overall the project has been great, and a fantastic opportunity for me. With a budget ten times greater than anything I’ve previously worked on, and a much bigger crew, and the Alexa and Cooke S4s to play with for five weeks, and all those HMIs, I’ve been quite spoilt. All the other heads of department are older than me and have worked on huge TV shows, and I can safely admit now that I was incredibly nervous when we started, but everyone is very, very happy with how the film looks, including me. Hopefully it will lead to more good things.IMG_2966.JPG

Heretiks: Day 25

Heretiks: Day 24

Jimmy, one of the runners, has written a song about the shoot. He heard the 1st AD ask our steadicam operator, “Rupert, are you ready?” and that inspired him to go home and write and record a pretty awesome song. Some of the crew have been shooting a music video for it on a phone during the lunch-breaks.
We shoot in the corridor in the morning. Lots of chippies are waiting to break down the set as soon as we’ve finished on it. We move upstairs and once again reap the rewards of rigging the chapel lighting so thoroughly as we bash through a critical scene.
After work there is a pre-wrap party. A bunch of us end up at the holiday cottage where one of the actors is staying. The cottage has a VHS deck and a well-worn copy of Free Willy. Of course we put it on. Michael Ironside is in it.IMG_2952.JPG

Heretiks: Day 24

Heretiks: Day 23

More corridor and nun cell scenes today. Everyone is tired, including the actors, and as a result they need more help from the lighting to look good.
We fly out the wall that has the window in it, but we still need the light to look like it’s coming through the (off-camera) window. So the art department remove the window from the wall and the sparks rig it to a C-stand, surrounded by flags.
We do a fight scene involving a sharp item being used as an improvised weapon. We’re about to shoot a cool 2-shot of the actors struggling on the floor, dutched almost 90 degrees. But the point of the sharp item isn’t showing up on camera and looking threatening enough. We’re short on time, so I prop up two torches on my wallet on the floor behind the actors, to edge-light the weapon. Not the first shot I’ve lit with my torch, and it probably won’t be the last.
Just two days left now.IMG_2950-1.JPG

Heretiks: Day 23

Heretiks: Day 22

After 16 hours at home (half of those asleep) I returned to Wales late last night. Only four days of the shoot left, including today, and we’re powering through the material at a good lick. All the sets are rigged so it’s not hard for lighting, but we still have to be careful. We rush the first take of a close-up on one of the lead actors and she doesn’t look good. I insist on another take and we take five minutes to massage the lighting and help her out. It’s totally worth it. The DP has to make the cast look good, and the fact that the pressure was on from the 1st AD is not an excuse that the producers will give two hoots about when they watch the rushes.
We do more steadicam shots going from corridor to corridor and another 360 degree shot in the chapel. There are few easy shots with Paul and that’s a great challenge to meet. This shoot has given me a lot of confidence.
Today we shot over eight minutes of screen time. We’re all very chuffed about that.

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Heretiks: Day 22

Heretiks: Day 21

Christmas music is playing in the dining room as we eat breakfast. There is a deer feeding event featuring Father Christmas in the grounds of the castle today.
We shoot mostly in the cell and corridor again. For the first time we venture into a second corridor linked to the first. But this one has windows, so the guys put up a 6K and a 4K firing in from outside. We don’t have the space to back them off enough to match the light levels of the adjacent “candlelit” corridor. So we rig up the iris motor and I do a stop pull from about T2.8 to T5.8 as Rupert steadicams from the darker corrridor to the brighter one.
Sometimes when you set up for a scene you put in lights through the obvious windows and it just looks great straight away. Today there were a lot of scenes like that. Half the battle is getting your backlight in without the lamp being in frame. Then it’s coming in with a key that’s sidey enough to have shape. If you’re doing the kind of spinning steadicam shots Paul loves it can be very difficult not to have somewhere in the move where the lighting looks flat. Today the coverage was a little more conventional and that really helped.
In our last hour we move up to the chapel and bash out a small scene in three set-ups which all look great. The camera and lighting teams move like well-oiled machines so I can deliver the goods in record time.
We wrap five minutes early and I’m off like a shot with a runner/driver to the station. I’m heading home to Cambridge tonight for a brief but needed break from the world of this film.IMG_2934.JPG

Heretiks: Day 21

Heretiks: Day 20

A week to go. A party atmosphere is already developing. Rupert has decorated the magliners with tinsel and Xmas lights, and a box of Roses has appeared by the checks monitor.
Bex from Ren joins the crew for a couple of days as camera trainee. She covers for George in the never-ending battle to get a Teradek signal from one room to another.
I do a lot of walking up and down stairs while talking into a radio.
Rain messes with our plans. We shoot bits in the nun cell and surrounding corridors, and a scene in the chapel upstairs. This latter set we light for daylight for the first time. We have 15KW of lamps burning. Ben rigs a Joker Bug, a small 400W HMI, behind the false window, and we have larger HMIs coming in from the corridor and the loft above.
We shoot the nun cell redressed as a different room. It’s very hard to light a desk that is away from the window and the ceiling gobo. I shall ponder this problem before we shoot in there again.
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Heretiks: Day 20

Heretiks: Day 19

I feel like crap when I wake up, but by the time we start shooting I’m merely sniffly and a bit achey.
Last night I spotted on today’s call sheet that heavy rain was forecast and a day exterior was scheduled! After I pointed this out, the scene was bumped and so we’re shooting mostly in the nun cell and corridor today. After reviewing Javier’s edits with Ben, we decided that 650s on the ceiling simulating candlelight look best with a layer of tough-spun diffusion on, as per the chapel set, so this morning we diff the 650s in the corridor set too.
The nun cell has one small window and a gobo grill in the ceiling, so the lighting options are very limited. Though sometimes less is more. We do a night scene and, for the first time, I eliminate the 2.5K HMI punching in the window, going just with the 575W HMI coming in through the ceiling gobo (with opal diffusion and steel blue gel) and a kino in the window (with steel blue). We use bounce boards to bend the light onto the actors when these sources cannot reach them.
We bump up a candle in the room with a 300W tungsten fresnel. Ben fashions a black-wrap snood for it which makes its patch of light very controllable. Max fades it up and down in sync with the candle being lit and blown out.
Later, for a different scene, the 2.5K comes back into play. It works best when the beam misses our heroine. She’s just lit by the natural bounce and the diffusion caused by the impure ‘glass’ in the window. The shaft of light, combined with the textures of the set, give the image a beautiful painterly quality.
I regret that I cannot give a more convincing impression of nighttime in the cell. I would love there to be black outside the window, but any lamp powerful enough to put sufficient light into the set also makes the window itself turn white, as if there is a bright sky outside. If the window was modern, clean, fully transparent glass that would not happen, but this is a period film. I would also love to make the candlelight appear to be a much brighter source than the ‘moonlight’ coming in from the window. But there isn’t room. We can bump up the candlelight slightly in a mid or close-up, but in a wide there’s nowhere to hide anything.
One of the last shots of the day is a pick-up from a Tretower scene with an off-camera fire. The FX boys, Warwick and Aaron, bring in a fishtail – a small flame bar – along with a wind machine and smoke to replicate the exterior conditions indoors.

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Heretiks: Day 19