The Great Timelapse Compendium
Part 3. Basic SDR & HDR Post production workflow
In this article I’d like to share with you 2 of my timelapse post-production workflows. Although the simplest timelapses might be put together using just a set of JPG files and a Quick Time Pro, being a professional and willing to achieve better results requires a bit more complicated approach and you’ll need both tools and software to do it. This article is dedicated to intermediate and more advanced users and is not intended to be software manual, so I assume you’ll find your way basing on the general directions I give.
Standard dynamic range (SDR) timelapse post-production workflow
This workflow was designed be myself to get the most of your RAW files and take the advantage of the rich 12-14 bits color depth of RAW files from DSLR. It is based on a philosophy which remains true for all other digital image processing disciplines be it a photography, astrophotography, film post-production or motion design.
The principle is simple – in order to get the best image at the end you need to retain the original rich information contained in the source files as long as possible during the workflow and use as few transcoding steps as possible to prevent image degradation.
The technical details regarding the timelapse shooting are not a subject of this article, so I don’t want to get into details here.
The only things to note here are:
- It is worth it to shoot 2 formats at once: RAW files for standard production workflow and small JPG previews in order to get the quick preview of the sequence
- The RAW files should leave some free resolution for croping/panscanning in post. Unless you have too much storage on your cards and excessive processing power in your office, better keep the files 50%-100% larger than the delivery resolution. Shooting on 5D MK2 I usually set the “Small RAW 2” settings which are around 2700 x 1800px
2. Quick preview
The idea behing creating quick previews is to be able to quickly check the contents of the sequence and also provide editors with the footage right after the shoot for offline editing, long before the full resolution masters are processed. Creating previews out of JPGs is fast and can be carried out even on a laptop on a set. Processing RAW files or full HDR workflow is very time consuming.
Assuming you have the JPG files stored separately form RAW footage, you can generate a quick preview using various software options:
- Quick Time Pro 7 is really fast and is just right for this purpose, so simply import a sequence and render to any preview format you like at decreased resolution (1080p is fine) for a smooth playback.
- After Effects is also capable of doing the thing, but it’ll be slower.
- A super fast solution for batch conversion would be setting up an Apple Compressor on a multi-core workstation with the Qmaster.
Here is where the real thing begins. The goal at this stage is to initially develop RAW files, import them to to Adobe After Effects, which is the only reliable program (so far) that is capable of converting a sequence of RAW files to footage, and render the source sequence in high resolution.
Isolate stills sequence
The first thing that needs to be done is getting the clean set of stills into one folder. Isolate the beginning of your sequence, the end, check for missing frames (Adobe AE will be so nice to tell you if frames are missing) and copy/move it to the separate folder.
Develop first frame
Open the first frame of the isolated sequence in Adobe Camera Raw (or Lightroom if that’s what you prefer) and apply the basic adjustments of the exposure, color, contrast etc.
If you have a sophisticated look in you mind that needs a lot of image manipulation it is better to get as close as possible at this stage, but don’t overdo it in any aspect that would cause the image to lose information (for example by applying excessive contrast).
If you head for more less natural look of images try to focus on setting the exposure and other development details in a way that will get as much details as possible form the RAW files. In this case what you want to pull out from RAW files is not a punchy an visually stunning image, but the image that is as rich in details as possible. So don’t exaggerate with contrast and color manipulation, but focus on getting rich details from shadows, preventing the highlights from being overblown and reducing the image artifacts.
A note on white balance
If you shoot a scene that is changing in terms of lighting (for example day-to-night) AND you’re going for RAW workflow, it is worth it to shoot on AWB setting. This is important for generating better Quick Time previews and is crucial for getting the proper color balance with AE-only workflow. If you’re doing a workflow that is based on LRTimelapse it does not matter, because you’ll be overriding the settings anyways.
If you shot AWB and want to take the advantage of the WB settings recorded in each of frames, it is absolutely necessary to keep the WB setting in ACR to “As Shot” – this is the only way to tell AE later that it should read the WB setting from each frame. If you override WB of the 1st frame, all further frames will be developed with the setting you set accordingly (Unless working with LRTimelapse).
3. Test your settings for other frames
It is wise to save your development settings and copy/paste them to other frames in your sequence, especially if you shoot in light-changing conditions. This will let you assure you did it the right way and that the developments will make sense on further frames.
After you’re done with checking, be sure to go to the folder with the sequence and delete all XMP sidecar files generated by ACR or Bridge in that folder during the testing process. Be sure to keep the first file for the first frame however! This is necessary to prevent AE from changing the settings during the sequence.
4. Set the color depth and the resolution of RAW development
There is a small link at the bottom of the ACR interface, just underneath the picture. It allows to choose the spacial and color resolution of the developed images. Be sure to set it to 16 bit. If you shot small RAWs, use the original spacial resolution, but if you shot full res RAWs, set it to about 150% – 200% of your delivery format resolution.
Make sure to set you AE project setting to match the ACR color resolution – even if ACR is set to 16 bits, if AE is set to 8bits you won’t get the extra color resolution.
5. Import sequence in AE
This is pretty simple. All you need to do is create a new project in AE, drag the previously prepared folder to the file browser in AE and the software will recognize and import a sequence for you. If you add the stills sequence to render queue, AE will create a sequence with the right settings for you. Real time saver.
6. Apply initial effects
At this stage you may apply the GB Deflicker filter, motion blur or other filters of your choice to the footage and/or perform motion tracking / stabilization to remove any camera shakes. At this stage apply only the basic effects for the initial processing of the footage. The final look will be created later, so don’t worry about that.
7. Render your Masters to an information-rich format .
Up to this point we’ve been working on an information- rich material. Unless you decided to switch to 8bits, the original color resolution of the RAW files was preserved. Rendering to an intermediate format is the first step in the workflow where you may lose information. It is essential to understand it and keep under control.
There are many factors contributing to the choice of your masters format – type of project you’re doing, platform, processing power and storage limitations. Let’s have a look at a few choices, starting from the highest quality:
Uncompressed 10+ bits files
This is the workflow that is common for serious VFX/Posrtproduction studios. If you’re doing everything on your single workstation (even a good one) probably that’s not the best choice. This will create LOTS of data. You’ll profit from that if you’re working with additional VFX extras added on top and/or you’re grading the project on a dedicated color grading workstation with serious software (such as Resolve I used to work with). Uncompressed will allow to process same files in a few steps not losing quality (no transcoding involved) and looking at the grading performance it’s the best choice when it comes to grading large resolutions (2K+) in a realtime. This requires a fast RAID storage, but that’s something you usually have on a dedicated grading workstation.
This is the second option on the high-end side. If you really need to retain all information for grading, go for a 16 or 32 bits DPX. It’s probably slower than uncompressed, but it’s a standard in post pipelines. If you’re editing with a Premiere it handles DPX sequences nicely. Not sure about FCP and Avid. Resolve I use for grading takes them also easily, so that’s a reasonable quality-oriented workflow I used to go with.
Apple Pro Res (Mac) or Cineform (PC)
A good choice for most cases, especially if you’re editing on a laptop or a smaller workstation. If you’re on a Mac you can work with Apple Pro Res, for a PC you’d stick to Cineform. I usually work with ProRes 4444, for less demanding projects I go with Pro Res 422 HQ (note with 422 your color encoding resolution is much worse). Be sure to render to 10 bit color resolution to preserve as much of the color space as possible.
Pro Res is a very good format for painless editing even on slower machines and will retain sufficient amount of quality for many jobs.
Avoid delivery formats
Never render your masters to anything like MPEG, H264 or other delivery formats, which are highly compressed and have limited color sampling and depth (usually 4:2:0 and 8 bits).
4. Editing and grading
At this stage you have the high resolution footage ready to edit and grade.
You’ll probably be able to edit it directly, if not – do your offline edit on the Quick Time previews and switch back to masters at grading stage.
Grade using your preferred software. I do my stuff always with Resolve, but there are more and more options for basic grading in the editing software or very well integrated with editing software (for example Premiere and Speed Grade).
HDR timelapse post-production workflow
If shooting in SDR and processing using the workflow above is not enough, you may try the HDR workflow. Be conscious however, that it is really time-consuming and computing heavy.
The basic approach is mainly the same, however some other techniques and software are used to merge multiple exposures to HDR 32bpp images. To keep things simple, I’ll describe only these steps, that differ from the workflow presented above.
The same rules as in SDR workflow apply, but additionally, you need to shoot stills using exposure bracketing. 3 stops, -2/0/+2EV is fine in most cases.
The shooting for HDR is a separate subject and it won’t be covered in the post-production chapter.
Some crucial notes below:
- Make sure to shoot with low ISO, on a 5D use native ISO settings (160/320/640/1250) to get as low noise as possible.
- If you’re shooting with a wide angle lens and aim for pushing the material in post particularily using Tone Mapping, make sure to shoot with the aperture of at least say ƒ/4. If you shoot on ƒ/2.8 on a full frame camera on a medium-quality lens, the exposure drop towards the corners of the frame will be as high as 2EV (2 stops). That’s a lot and that’s something that will definitely make a serious isse for tonemapping later bringing terrible noise and artifacts. Stepping down the aperture reduces vigneting and the frame is illuminated more evenly.
2. Quick preview
Same workflow as for SDR processing.
Render out the previews from the middle exposure (+0EV).
There’s a simple trick to isolate them (at least on a Mac). Set Finder so that it arranges the icons in a grid as you resize the window. Resize window so that you have 3 columns of icons. Drag to select just the middle column and copy to a new folder. Proceed from there.
The goal at this stage is to merge the subexposures into HDR frames at 32bpp, develop in the similar way as in SDR workflow, import them to to Adobe After Effects and render the master footage in high resolution.
3.1. Isolate stills sequence – As described above.
3.2. Batch-merge using Photomatix Pro
Using the batch feature of Photomatix Pro (PMP), run a batch on a set of files to generate a sequence of HDR images. There’s an easy way to tell PMP to process files in group of 3 files to match your -2/0/+2 bracketing subexposures. At this stage we get the set of 32 bpp HDR images that will be developed in the next steps. This will take time, so grab your kettle or play some music.
In Photomatix you have 2 options for storing HDR images. Both are 32bpp so are safe in terms of quality.
- HDR format is useful as an intermediate format if you intend to do tone mapping or exposure fusion in the next step in Photomatix and then edit/grade your tone-mapped images. HDR will be handled mostly by Photomatix and maybe some 3D software, but is not really used in post piepelines. That’s the workflow I used for The Chapel which makes use of a highly pushed and tone-mapped look. Long story short, if you stick to HDR you’ll be doing step 3 below.
- Open EXR makes sense if you’re using Photomatix only for merging files, but then you do your processing elsewhere. Open EXR is handled by more programs and is also handled directly in Resolve. I use this workflow more often recently and used it for example for Rebirth. This option assumes you skip step 3 below and go directly to edit/grade.
3.3 Develop HDR files and compress them to something editable
You got the 32bpp HDR files from photomatix and you need to deal with the information and compress the dynamic range to something that editing software and displays can handle.
At least 3 approaches are possible
- HDR > Tonemapping in Photomatix > TIFF/JPG Sequence > QT Merge to footage > Edit > Grade
- HDR > Exposure Fusion in Photomatix > TIFF/JPG Sequence > QT Merge to footage > Edit > Grade
- HDR > Import directly to AE > Save Intermediate (optional) > Edit > Grade
The workflow for 1&2 is similar, except for the mode of Photomatix you’re using to convert 32bpp to 16bpp.
Develop one frame of HDR sequence to find your settings
At this point we do the development of the source files in a similar way as described in SDR workflow, but we have HDR files instead of RAWs and use Photomatix for all creative decisions – we can use Tone Mapping or Exposure Fusion features to go from 32bpp to 16bpp images. Play with all settings that PMP provides you with and keep in mind that the more aggressive the development, the more time you’ll need to spend checking the settings on multiple frames. Make sure to save your settings at the end in an XMP file.
Test your settings for other frames
This step is even more important than in SDR workflow. Since the HDR development might produce much more artifacts, so you need to carefully check further frames in different points of the sequence against the artifacts of the deveolpment recipe. Simply open a few files across the sequence and develop using the stored setting. If any artifacts appear you’ll probably need to apply less severe processing and re-test.
Batch-develop the sequence
This is the second batch you need to run. Basing on HDR files and your well-checked recipe, convert the HDR files to 16-bit TIFF files. Unfortunately this is storage consuming and PMP won’t offer you any other of convenient intermediate formats to keep your 16-bit data. For low-quality computing-lightweight workflow you can export to high quality JPGs.
4. Import sequence in AE
As described above for SDR, but use TIFF files instead of RAWs. The rest of the workflow remains unchanged.
We’re just scrathing the surface, but hope this gives you a good starting point.
Thanks for reading and your interest in my blog. The skills and know-how are provided to you free of charge, but please leave a comment below and share if you find this information helpful.