It never fails. It’s usually on a nice saturday afternoon. The movie's been shipped and most of the team is off, but you’re scheduled to be at the studio on call for stereo color timing notes from Los Angeles. And it goes down like this:
The emergency call comes from management: There’s a shot coming back your way. They found a dark one pixel scan line that is showing up behind the mountains across the entire frame in the opening sequence of the movie and only in the left-eye. It’s showing up in the first 300 frames. Please investigate immediately.
The first thought in my head: really? You have to be kidding.
but I answer back on the phone: Sure I’ll take a look right now.
Take a breath.
With the shot in front of me, I scan it from head to toe; I flip through all the frames. I need to get a baseline. Sure enough there it is. Like they said, there is a single one-pixel scan line going through the entire frame. It’s amazing they even spotted this.
Check the mono film frames. It’s not there, meaning it’s an artifact I’ve introduced into the shot during the time I worked on it. How did I miss it? I’m guessing it’s the interlacing on my 3D monitor that probably hid the offending scan line from me.
I open up the shot. First thing I need to know - can I recreate the issue?
Ten minutes later as I’m working the supervisor calls from LA.
Have you found anything yet?
I confirm the symptoms. It’s definitely a problem in the shot.
How long do you think it’ll take? They want this ASAP.
I answer truthfully:
Give me a half hour so I can diagnose the issue. I can give an update then. But most likely it’ll require some time as 300 frames are affected.
Now the next thirty minutes are vital. You start from the bottom and you work your way methodically backwards into the shot to isolate the culprit causing the one-pixel horizontal scan line. There is no time to panic and you need to just rip through your shot to see where it failed. Each shot is a different beast; many of them are stubborn and will refuse to cough up the answer to the puzzle. Fortunately this one does not fight me. This one renders fairly quick and allows me to interact with it. I quickly discover there’s a render of a cable car that is mismatched in image size with the rest of the other renders. I throw an image crop over it and it’s fixed. I spot-check a few other frames - no more one-pixel horizontal scan line. I’m satisfied. Hit the render button.
I allow a sigh of relief.
The production coordinator walks by.
How is it going? she says.
Good. Good. It’s on the farm now. Shot should be done in an hour or so. I’ll let them know as soon as it’s ready to be transferred back out to them. It was a simple fix.
Maybe too simple. This gnaws at me and I’m suspicious. Ten minutes later, I check on the frames in progress and realize something is horribly horribly wrong. I have successfully removed the offending single pixel scan line, but I’ve also removed ALL-OF-THE-MOUNTAINSIDE-CABLE-CARS! from the title shot.
They won’t be happy.
Start the clock.
Open up the shot immediately and dive back in to see what the problem is. Was something accidentally deleted when I was in there? Did I break something? The possibility of having to start over is too grim to consider so I brush those dark thoughts aside. I focus on my previous fix attempt. Was I too liberal with the image crop? I try another couple of alternatives and something works. I verify everything looks right. I verify it again. Close the shot and re-send to the render farm.
Stop the clock.
Ten minutes have passed. Thankfully not too much time lost.
An hour later and having double-checked, triple-checked on the in-progress frames during render, everything looks good. The shot looks healthy and stable. I step through every frame in the shot forwards and backwards looking for errant scan lines and other issues. I notify management that the shot is ready to be shipped.
I get a call from LA a few hours later. Everything looks good.
All done. Until the next shot.