12 post-production tips to make your renders more impressive
Images right from render rarely look incredibly photorealistic. For that you need to invest some time into post-production. To make it easier for you, artists from Mondlicht Studios shared a bunch of tips on workflow and exact tools they constantly use...
Work with passes
Rendering a single beauty pass and trying to make post-production on top can work for some cases, but the better workflow is the multipass workflow. It’s flexible and gives you the ability to control literally everything. To have the best control and ease of work, render as many render passes as needed for an image. When you're done with rendering, you need to compose them to recreate your beauty pass (google multipass workflow + [your software]).
In this case, your result will be 100% similar to your beauty render, but with the possibility to adjust every layer individually. This workflow is well known and the way to go in the industry. It may seem a bit more time consuming at first, but it will save you hours of work in post as soon as you get used to this workflow.
Make enough masks
Cryptomatte has improved working in post by a good stretch, but still more and other custom masks can be very useful. You can, for example, put one dull, grey material on everything and render black and white masks with light sources (or combine 3 lights with RGB and extract the channels for masking). Another thing might be a custom transparency for glassy objects or - for cars - an accurate alpha for the interior transparency of the windows, which won’t necessarily be rendered with cryptomattes. In short our message: Create custom masks when needed, post will be very happy!
“I don’t work on post-production a lot, but I am always trying to make sure that artists have all necessary renders to make the process as fast and easy as possible. So, don’t be lazy and prepare everything which is useful for those who’ll deal with post production. But talk to them first.”
- Maksym Khirnyy
Create a plan
First of all, always work in 16-bit and with a defined color profile. Render in 32-bit or at least 16-bit. When this is set, create your basic composition with a structure. You can either start in 32-bit and make some adjustments, or directly start in 16-bit from your renders.
Then create a new layer in Photoshop on top of everything and mark the areas you want to fix. This will be your own comments and hence, your to-do list. This simple action allows you to clear your head from a whole list of comments and concentrate on the retouching. If something jumps into your eye while working, just add it to the comments and keep going with your task. Check back from time to time and compare whether you adjusted everything you wanted.
References are an absolute must-have. Even if you think you perfectly understand what you want to add to your image, or how you want to make it look. It’s not only about believability but also about color grading and other post-production tricks you may apply. Gathering references might take some time, but it's totally worth it. You’ll find a lot of exciting solutions which will boost your imagination. It will also allow your eyes to rest from your render; and when you look at it again, you might notice a lot of details you haven’t seen before.
A small hint: Use google advanced image search and specify large resolutions (fe. 15 megapixel and above) to filter too small resolutions from your search results.
Keep an eye on the Photoshop document structure; try to make it as logical as possible and name your layers*. It might look like additional and unnecessary work, but it will save you a lot of time if you need to change something in the layers. What’s more, if you’re working on a commercial project, your client may ask you to make some adjustments even in some months. If your working file is in complete chaos, it will take an eternity. Keeping your files organized is a good habit, which will make your workflow more productive and efficient.
*) Yes, we know how it goes and we sometimes don’t name EVERY layer as well. But a general structure, logical groups and names for them are very helpful. You might think it’s a bother, but you will thank yourself later on along the process for doing it. Let Dima tell you why:
“Pretty often there are several people working on the image. Junior artists can do some basic retouching, middle or senior adjusts the image and the art director may add some final touches. What’s more, the client is also working on the image preparing different layouts for print. If the file is messy, it will be uncomfortable for everyone to work on it and it will take a lot of time. Even if you are not going to share the file, keep a good structure. This useful habit will help you in future”.
- Dmitriy Glazyrin
Tools and tricks
Add grain and rough it up
Impeccable purity of the renders might look tempting, but this is what tells a viewer that he’s looking at a 3D image. If you are aiming for a photorealistic effect, the grain will help you to achieve the result. You may apply Noise effect in Adobe Photoshop’s Camera Raw, but we encourage you to try this feature in CaptureOne too, because the options for noise there may give a more natural effect you can control in more detail.
Match the sharpness/blurriness of your render to the backplate; and throughout all assets you are using. If you are adding digital matte painting work, make sure you don’t have different sharpness and grain and try to match it as best as possible.
Compare the raw render with the final image. If you want to explore more about the process, you can find a breakdown video here.
Explore Camera Raw
Camera Raw in Photoshop is an excellent tool for final grading and post-production. You can play with the overall mood, make the colors more vibrant, change the exposure, add some noise, and even apply some presets and filters. Thanks to the latest update, the tool is very intuitive and easy to explore. Always do this with a smart object of your whole image flattened to one layer (or composition). You can also save the preset of your Camera Raw adjustments as an XMP file, but you may need to pass it on as well. So to make it more easy, add final effects and Camera Raw on a smart object in Photoshop.
Explore adjustment layers
Adjustment layers are crucial and very flexible tools that give you amazing possibilities for retouching. Unfortunately, not all of them are available in 32 bits (but thanks to Adobe, now we can use the “Curves” tool in 32 bits, which is one of our favorites). Important tip: Non-destructive workflow! Always create an adjustment layer as a separate layer. Yes, this turns your PSD into PSB, but also allows you to come back and change the layers at any time.
“Except for the popular curves adjustment layer, I really encourage you to explore all adjustment layers. Gradient Map is a highly underrated but amazing tool and so is Selective Color. To get the most from it, try different blending modes and opacity, as well as the layer style Blend If (see screenshot below)”.
- David Schäfer
Explore masking tools
Yep, you can create many necessary masks in a 3D software you’re using, but sometimes you need to add masks that can not or only hardly be rendered. You can go with the obvious solution and use the black and white Brush tool, but it’s way more efficient to explore all the tools Photoshop offers and choose the best one for every situation. Automatic Object detection, Replace Sky to create a nice mask for your sky, refine mask tool, paths, etc.
There are a lot of options to modify your image in CaptureOne. Also, you can apply one of the different styles and look if it works for your idea. Sometimes it’s handy to go through them and get some inspiration. It’s a fantastic program when the retouching phase is over, and you can check some interesting solutions for the overall mood.
CaptureOne also lets you work in layers for the adjustments including masking, which can come in highly useful. Also the detailed color grading options are amazing.
Try to render 2-3 different AO maps and mix them in Photoshop. You’ll see that you get way more flexibility to play with soft shadows, emphasize the parts of your artwork and separate the objects in your scene. It’s effortless but a beneficial tip, which adds realism to your work.
Some tips on passes you should explore as well: Curvature, lightmasks as mentioned in ‘Make enough masks’, fresnel (combined with Ambient Occlusion), make use of Normals, reflective occlusion (rarely used, only in extremely open and detailed multipass workflow, but can come in handy anyway), thickness/SSS can add a nice touch in some cases, position, UVs, motion vector… you get the idea. Don’t hesitate to test and check how these passes can be useful in post production.
But keep in mind, the more passes you render, the longer your render will take. Depending on which passes the addition time varies a lot, but try to strike the best balance. For stills it can be a good idea to render the basic passes in one render and then, with another sampling/quality setting, the additional passes that are not impacted by lighting or global illumination.
We hope that gave you a few ideas and will be able to help your workflow and image quality!