Despite all the 'artistry' involved, generating convincing CGI can be seen as a very technical skill. Like with many technical skills: 20% of the knowledge can get you 80% of the way.
The following is a list of steps that I don’t recommend you perform mindlessly, but incorporating them in the workflow of most beginners would usually bring a significant improvement in their work.
The key to boosting photorealism in post production can be reduced to two main tasks:
imitate all the optical phenomena that are missing from our renders (as they never involved a real lens nor a real camera sensor)
processing these renders like traditional filmed footage (which kind of makes sense if you think about it)
The Importance of Color Correction
All professional footage that is shot today goes through meticulous color correction processes as a necessary step in the editing process. This isn’t a luxury of overly perfectionist creators, but rather a basic component of good looking products. You wouldn’t cook without salt and spices, and you shouldn’t deliver visuals that didn’t undergo color correction.
For animation post-processing, I recommend using Da Vinci Resolve (even the free version). It's akin to treating your animations as you would any conventional footage shot with a DSLR. For still images, Lightroom or Photoshop is ideal, but for those without access to these, free online tools like Pixlr can also do a decent job.
Step-by-Step Enhancement
Step 1: Bring it to the Correct Color Space
If you're rendering animations in the EXR format, which offers lighter files and a wider dynamic range than PNG, the first step is to convert your images to the Rec709 color space. This involves applying two color transforms, which are explained thoroughly in Polyfjord’s tutorial that you can watch here: Polyfjord Tutorial.
Step 2: Apply a ‘Look’ LUT
Enhancing colors in unique ways can significantly alter your visuals, giving them a more cinematic appearance. Using the same look-up tables (LUTs) that videographers apply to their footage can introduce a distinct style to your renders. These LUTs are available for free online, and many professionals sell their custom packs, allowing you to emulate their specific aesthetic.
Step 3: Exposure, Contrast, Saturation
Here’s the surprising (or at least less intuitive) part of the workflow:
Reducing the Saturation and increasing the contrast immediately elevates the photorealism of your animation. CGI often comes out of the box looking much more saturated than real-life footage. Adjusting these two settings (contrast and saturation) often involves balancing them inversely to achieve a more realistic look.
When adjusting the exposure for a 'cinematic' look, you may find that lifting the gamma toward the highlights often does the job. In other words, it's generally good to lift the medium values in your render towards the brighter exposure so that they are closer to the brights than they are to the darks. In addition to giving a hint of cinematic exposure, it will also look better on most screen then if you would aim for a darker final grade.
That's because having a high quality definition in the darker parts of the image is technologically difficult to achieve with a cheaper screen, especially after the compression your footage endures when uploaded to the social medias.
We can see a very slight difference in the height of the waveform, but it actually goes a long way in making the visuals more realistic
Step 4: Layered Effects
Consider these additional touch-ups, used sparingly:
Sharpen: CGI tends to have a softer look. A bit of sharpening can add the impression of rich detail, akin to what you’d expect from real footage.
Chromatic Aberration: This effect mimics the color fringing caused by lens imperfections and can add an authentic touch when applied subtly, especially at the edges of your composition.
Lens Reflections: When you have bright reflections or light sources in the frame, adding the 'lens reflections' effect can replicate the imperfections seen in real camera footage.
Grain: Finally, adding grain can prevent your footage from looking too pristine. Realistic film grain helps convey that this could indeed be footage shot with a camera.
You can find these effects in the color tab in DaVinci resolve and apply them on one of the later nodes in your node tree.
Bonus Tip: Noise Reduction
For those using ray tracing render engines, dealing with 'fireflies' or noise can be a challenge. While Blender's noise reduction tool is effective, it sometimes doesn’t fully clear up noise because it doesn’t account for the noise's shift between frames. Da Vinci Resolve’s Noise Reduction can analyze and average multiple frames, greatly reducing noise.
The noise reduction effect can be demanding on your system, so it might be best to only enable it during the final export.
To enable the effect you simply find it in the search bar in the top right corner of the color bar, drag it to one of the nodes and pull up the temporal threshold controls:
By integrating these steps thoughtfully, you’ll not only enhance your renders but also deepen your understanding of the post-production process, improving your skill set as a 3D artist.
Best of luck and go render 'em marvels!
Gabriele.
About the author
Gabriele is the creative director in our studio, with several years of experience in both videography and CGI.
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