|A CreativeCOW GenArts Sapphire tutorial
©2009 Ra-ey Saleh and Creativecow.net. All rights reserved.
In this tutorial, Ra-ey Saleh will reveal how to use Sapphire effects to fix 3 everyday technical issues: wide-angle lens distortion; aperture-pulls; and flickering GFX. These are undocumented ‘hidden tricks’ and will work on all Sapphire platforms (Avid, AvidDS, After Effects, FCP, Autodesk, Shake and Nuke).
Mention ‘Sapphire’ to most Editors and they’ll immediately think of all the cool filters (such as FilmEffect, FilmDamage and BleachBypass) or transitions (such as DissolveGlow and SwishPan). These are what I like to think of as ‘stylistic’ effects. However, in this tutorial I want to look at 3 of their more ‘practical’ effects which can be used to fix common technical issues. Although none of these effects were specifically designed for these purposes, I think you’ll find with a little lateral thinking that they’ll perform as good as if they had been.
I’ll use Avid Media Composer as my platform, although all of these effects are common to Sapphire in other applications, such as AvidDS, After Effects, FCP, Autodesk, Shake and Nuke. If you’re a Non-Avid user, you may need to adapt my instructions to suit your specific software, but you should obtain equally successful results.
You’ll need Sapphire v2 or higher on the Avid to have access to all of these effects (for AvidDS you’ll need v3; for After Effects and FCP v2; Shake and Nuke v1; and Autodesk v3).
(or the “The Lens Distortion Corrector!”)
Those of you who are familiar with After Effects will be aware of its great ‘Optics Compensation’ effect, which allows you to easily remove the lens distortion you get from wide-angle lens. Sapphire’s WarpFishEye effect is perfect for distorting an image to create this look (cool for those security camera POVs) but by reversing the parameters you can also use the effect to actually eliminate the distortion (just like the AE effect).
(My example Project Files are downloadable from the top of the page. They are HD 1080/50i in format. I have also included my Avid Project (‘Sapphire Tricks 1080 50i’) illustrating the various steps of the process, so you can easily follow along.)
The barrel distortion is clearly evident on the door frames, as are the sides of the lens hood on the left and right of frame. Traditionally, you would simply ‘resize’ the image to get rid on the lens hood, but the barrel distortion would still be very apparent (see below):
Here’s where WarpFishEye comes into its own. Apply the effect (from the Sapphire Distort Category) to your shot. Change the ‘Wrap X’ and ‘Wrap Y’ drop-down menus to “No” as you want to be able to see any black edges on the top and bottom of frame. Then simply alter the ‘Amount’ value to a negative number, I found “-0.200’ is a good figure to start.
Now make slight adjustments to the ‘Amount’ and ‘Z Dist’ sliders until you’re happy with the result. Here’s my final version:
Let’s look at another example, import the ‘WarpFishEye Example2’ Jpeg. Here you can see that the arcing on the top edge of the orange board is made completely straight using the WarpFishEye effect, something impossible in a traditional ‘resize’:
(or the “The Aperture-Pull Fixer!”)
If you’re an Online Editor, and if your experience is similar to mine, then probably the most common problem you’ll have to fix is the aperture-pull. That’s when mid-shot the exposure changes. Sometimes it’s a little, sometimes a lot. Sometimes you can simply ‘slip’ the shot in the Online to avoid the situation, other times you have to painstakingly grade it out. It’s fiddly, time-consuming and the results can still be pretty unimpressive.
Step forward Sapphire’s FlickerRemove! FlickerRemove is designed to remove the temporal flickering you can get from in-door fluorescent lighting, normally when shooting in a country with a different power supply frequency than the camera set-up (i.e. shooting in the UK with 50Hz voltage on cameras set to the USA 60Hz). In other words, it ‘levels out’ any luminance fluctuations in a shot. However, the source doesn’t have to be flickering for you to make use of this effect. There could be only one aperture change in a shot and it will still average any difference. To get a hands-on example of what I mean, import the ‘Aperture-Pull (RGB H.264)’ QT.
Mark the frame that has the correct brightness level and apply the FlickerRemove effect (found in the Sapphire Time Category). You will see an orange box appear in the Effects Preview Window (you can just about make it out in the still below) and the shot will suddenly get a lot brighter. This is temporary so don’t worry. Now in my experience, if the shot is fairly steady without too much movement (either in terms of action in the shot or camera movement) you can leave the orange box in its default location.
Simply park on the frame you selected earlier and press the ‘Set Hold Level’ button on the Effects Editor. The ‘Hold Level’ slider underneath will change in value to the average output brightness within the box at that frame (my example dropped to around “0.332”) and the brightness in the Effects Preview Window will return to normal. You will need to render the effect to see your results. Now, 90% of the time this has been all I’ve needed to do to fix my problem shot. However, sometimes it doesn’t “take” first time so you need to play with it a little to get it to work. Here are some further tips:
1) If at first it doesn’t work, re-apply the effect and adjust the orange rectangle box to fit a section of the shot that doesn’t have a lot of movement. This does not mean the shot has to be locked off, but if there is movement in the box that is affecting the overall brightness, this can cause a false reading.
Also, if the shot is moving a lot, you may want to keyframe the box to have roughly the same content inside it.
2) If the duration of your shot is long, it’s much better to use a “dummy edit” to narrow the portion of the clip the effect has to look at, again, minimising the chance of a false reading. For example, if the aperture-pull is just before the end of the shot, place a “dummy edit” (called an ‘Add Edit’ on the Avid) just before the luminance changes. Park on the first frame after the “dummy edit”, apply your effect and set your ‘Hold Level’.
3) In extreme cases - where the brightness fluctuates considerably - you may first want to split the shot into two parts, grade each as close to each other as possible, dissolve between the two, then “nest” both parts together with the same effect before setting your ‘Hold Level’. This should nicely “iron out” any remaining differences.
It should be stressed that FlickerRemove is no miracle worker and if sections of the shot are “burnt out” or overly “crushed”, you will not be able to retrieve this information as it doesn’t exist.
(BONUS TRICK: FlickerRemoveColor is for colour, what FlickerRemove is for brightness. It averages out any fluctuations in colour and is perfect for those ‘filter pops’; or exteriors where the colour temperature changes dramatically over the duration of the shot. You can even apply it on top of your FlickerRemove effect to remove any slight tonal changes it causes.)
(or the “The GFX De-Flicker Effect!”)
Often when GFXs are made and rendered to an interlaced format, any fine horizontal lines appear to “flicker” on broadcast and domestic video monitors. Sometimes a GFX person will have the foresight to apply the After Effects ‘Reduce Interlace Flicker’ effect (or even Blur the GFX slightly) to avoid this problem, often however, they don’t and you have to send the GFX back for revisions. Then of course there are those situations where this is not an option and you are left to somehow fix it in the Online. In the Avid, there is really only one option and that is to de-interlace the GFX with a Motion Effect, but this can actually cause more problems then it solves.
Import the QT called ‘Flickering GFX (RGB H.264)’:
On a broadcast/domestic monitor, the GFX will flicker quite badly (it is even causing banding issues in the still above). Now normally, I would apply a Motion Effect to the GFX, set it to 100% and experiment with the various image interpolation options to reduce the flicker: everything from Duplicated Fields to the normally fantastic FluidMotion (those of you looking at the Avid sequence I supplied can see my various failed attempts). The undulating results are actually worse than the flicker. And when I try to use other de-interlacing plugins I get similar results. So, what to do? Sapphire FieldRemove to the rescue! Simply apply the effect (from the Sapphire Time Category), change the ‘Field Dominance’ to “Upper First” if working in HD or Pal (“Lower First” in NTSC) and select “Merge” in the ‘Use Field’ drop-down menu. And render!
If the default is still not quite enough to completely get rid of all the flickering, just increase the ‘Scale Mo Matte’ setting until it is. I found doubling the preset to “8.000” worked perfectly for my example.
Now there is one caveat to using this effect and it should be obvious. You have to sacrifice the fields in the GFX (I mean, it is called FieldRemove...), which may or may not be allowed by the Broadcaster or suit the GFX. However, in my experience Broadcasters would prefer a GFX without fields than one that is flickering.
And that’s it. I would like to thank Todd Prives of Genarts for his help and advice in writing this tutorial. It was much appreciated.
I hope you learned something new, and please, if you have any Sapphire Hidden Tricks of your own, add them to the comments below. I would love to learn them!