A question I’m often asked is: “What are the recommended animation image file types?”
There are many different animation image file types available depending upon which particular software you may be using to create your animation such as LightWave 3D, Modo, Blender, Houdini, 3D Studio Max, Maya 3D, Cinema 4D or others. Out of the entire available list for your software there are probably many different formats that would be appropriate. Rather than listing all the details of many different animation image file types, which can leave you even more confused, instead I’m going to give you a few of the recommended animation image file types that I use for various purposes and explain why. This should give you a good place to start and you can then experiment with and add other file types as needed.
These are the recommended animation image file types that I typically use for rendering most animation projects.
- JPEG (JPG) – Quick proofs, low disk space, no alpha (or alpha in separate file)
- TARGA (TGA 32) – Simple compositing, isolated alpha channel (for older compositing apps), no other buffers
- Portable Network Graphics (PNG 32) – Simple compositing, integrated alpha channel, no other buffers
- OpenEXR_RBGAHALF (EXR-16) – Advanced compositing, High Dynamic Range (HDR), multiple buffers
Recommended Animation File Format
The first question I’m often asked about file formats from beginners is: ”Which animation file format should I use?“
Beginners are often surprised when I answer that it’s generally not a good idea to render to any animation file format. Sure, for some quick short tests you can of course use an animation/video file format such as QuickTime if your on Mac OS X, MP4 for other platforms or WMV for Windows. But for anything that will take a significant amount of time to render it is far more advisable to render a series of still frames to a single image file format rather than an animation/video format. There are many reasons for this. A few being the following.
In case of a crash, software, hardware or power failure you will lose the entire animation if you are rendering to an animation format. But if you are rendering still frames to a single image file format it will just lose one frame. You will retain all the frames already rendered. In that case you can easily pick right up where it left off to finish rendering the rest of the scene.
if you are rendering across a network render farm using the built-in network rendering panel or a third party render manager such as our DreamLight Constellation you can’t render directly to an animation file format anyway. Each LWSN render node will render a single frame at a time and needs to save that frame as an image when done. Depending upon the speed of each computer and the order of rendering, the frames may not even be rendered in order and wouldn’t be appropriate to save in an animation format anyway.
When rendering a series of still frames to a single image format you can easily spot check the frames as they finish rendering rather than waiting until the entire animation finishes rendering. If you notice a problem with any of the frames as they are being completed you can stop the scene from rendering, make adjustments and re-render just the problem frames rather than re-rendering the entire animation again.
By rendering to a series of still frames using a single image format you may use a lossless format that will retain all the detail of every frame as it was rendered. You may then simply open the image sequence in any video compositing or editing software for compositing (such as Blackmagic Design Fusion, Apple Motion, Apple Final Cut Pro X, Apple QuickTime Player or any other video editor), fine tuning and output compression into any final video format that you may need for final delivery, such as QuickTime, MP4 or WMV. This way your master files always retain their full pristine detail and you may compress the final video output files to various degrees based on how you need to use the video, such as for playing locally or uploading to YouTube, Vimeo, etc.
When rendering a quick animation for proofing purposes, where I don’t need high quality image files, I don’t need an alpha channel (or will save the alpha channel in a separate file) and I don’t want to waste much disk space then I render to the JPEG (JPG/JPEG) image file format. This is a 24-bit integer file format capable of displaying 16.7 million RGB colors without any alpha channel.
Here’s an excerpt from a chapter I wrote in the FreeHand Bible about Shockwave back when the World Wide Web was still new. The chapter included a description of various image file formats including JPEG.
The JPEG format, pronounced ‘J-peg,’ was developed by the Joint Photographic Experts Group as a variable compression scheme for photographic images. During the compression process you may adjust the settings in favor of better image quality or higher compression. The JPEG format is capable of handling true color raster images with color depths above 8 bits. This enables you to use thousands or millions of colors with 16 or 24 bit color depths… The only feature not offered by the JPEG format is transparency…
JPEG compression uses complex mathematical algorithms to attain compression ratios of up to 20:1. Typical images achieve compression ratios from 5:1 to 15:1 using a “lossy” compression scheme. This means that some information is lost as the file is compressed. The higher the compression ratio, the more image detail that is lost. The lower the compression ratio, the higher the image quality that is retained…
When rendering an animation that only needs simple compositing or post processing where I want an isolated alpha channel, I’ll sometimes render to the TARGA (TGA) image file format if I need compatibility with older compositing apps. Unlike JPEG this venerable old format can include an alpha channel for transparency.
Older versions of Photoshop lacked the ability to separate the transparency from a PNG out to a separate channel. Newer versions allow separating the transparency out into a channel mask. So TGA is mostly useful for older software that may not handle PNG alpha the way you need. If PNG alpha behaves the way you need in the compositing software you’ll use then PNG has better compression and would be the preferred format.
If I want to be able to access the alpha channel separately from the RGB data in older compositing software then TARGA is often better than the newer PNG format which can also include an alpha channel, which I’ll cover next. One big difference is in how some older programs read TARGA vs. PNG. Older versions of Photoshop and some other programs read the alpha channel into the transparency of the RGB layer itself, losing the background, when reading PNG files but keep the alpha as a separate channel when reading TGA files. So if I want access to the separate alpha channel while also retaining all the RGB data in the transparent areas of the frames, then I’ll sometimes use the older TARGA format for compatibility with older compositing apps. In newer apps that are fully PNG compatible I just use the more advanced PNG file type instead.
The TARGA format was developed by Truevision for their early IBM-PC TARGA graphics cards. The TARGA image format is a lossless format so it retains all the image detail of the render without any loss from compression. It uses a run length encoding (RLE) compression scheme that is much simpler than the compression used in JPEG or PNG formats so the files do not compress nearly as much. It’s an integer format supporting up to 24-bits of RGB data capable of displaying 16.7 million RGB colors similar to JPEG. The TARGA format also supports an additional 8-bit grayscale alpha channel for transparency when using the TARGA 32-bit format.
When rendering an animation that only needs simple compositing or post processing where I want an alpha channel for transparency that I’ll be using in newer compositing applications, I’ll often render to the Portable Network Graphics (PNG) image file format.
Here’s another excerpt from that chapter I wrote in the FreeHand Bible about Shockwave back when the World Wide Web was still new. The chapter included a description of various image file formats including PNG. This was back when the PNG format was brand new and not yet supported by web browsers. I was testing it with a beta version of a third-party plugin for Netscape Navigator 3.0 at the time.
The PNG format, pronounced “Ping,” is being recommended as a patent-free replacement for the GIF format. The PNG format was developed by the World Wide Web Consortium and CompuServe to provide a royalty-free GIF replacement. This format was specifically designed to transmit graphics over a network such as the Internet. As soon as the format is in widespread use it should quickly take over as the dominant raster image file format on the Web… It should soon become the standard format on the Web.
The PNG format is capable of compressing both indexed color (8 bit or less) and true color (above 8 bit) images. The PNG format uses a lossless compression scheme that is capable of compressing files about 30% smaller than the GIF format. The progressive feature enables browsers to load the first pass much quicker than the first pass of an interlaced GIF file. Not only does the PNG format support transparency but it also supports full alpha channel blending…
OpenEXR (EXR 16) Animation Image File Types – For Advanced HDR Compositing & Additional Buffers
When rendering an animation that requires advanced compositing or heavy post processing where I may want to use high dynamic range (HDR) and/or multiple render buffers, I’ll often render to the OpenEXR (EXR) image file format.
All the previous image file formats covered so far, JPG, TGA and PNG, are integer formats with up to 24-bits of RGB color information which allows 256 levels for each of red, green and blue for a total of over 16.7 million colors. That’s actually more colors than the human eye can see so you might think that’s all the color information you’d ever need and you’d be correct if the images would be used as-is. If however the images would be used for compositing or heavy editing in post-processing where colors will be heavily modified you’ll often end up with banding or loss of detail in shadows and/or highlights. The OpenEXR format is a floating point image file format which drastically expands the number and range of colors capable of being represented. Rather than being limited to integers from 0 to 255 for each of red, green and blue, floating point formats allow any number beyond and between those numbers so that it can account for everything from very deep shadows to the brightness of the sun or beyond. This is called high dynamic range (HDR). HDR images in formats such as OpenEXR may be heavily edited in post-processing without loss of color detail and may even be used to pull details out of deep shadows or overexposed areas. OpenEXR can handle 64-bit, 32-bit or 16-bit floating point precision. LightWave 3D’s full EXR is 32-bit and half EXR is 16-bit.
The OpenEXR image file format was developed by Industrial Light and Magic (ILM) and was specifically designed for use in visual effects and animation. OpenEXR supports both lossless and lossy compression schemes. It also supports multiple arbitrary channels or buffers which are particularly useful for compositing in advanced compositing programs like Blackmagic Design Fusion, Nuke, Blender, Natron, Flame, HitFilm, Apple Motion, Adobe After Effects, etc.
In LightWave 3D, if I only need the RGB and an alpha channel then I’ll render to LW_OpenEXR_RGBAHALF(.exr) on the Render Globals Output Tab. The “HALF” version uses 16-bit floating point precision which is usually sufficient for any post-processing I may need and the files are half the size of the full 32-bit precision version. If I need more buffers such as depth of field (DOF) or others then I’ll render to LW_OpenEXR_MultiHALF(.exr) on the Compositing Buffer Export Image Filter on the Image Processing Panel (Processing Tab of the Effects Panel).
For even more features and flexibility when using OpenEXR in LightWave 3D grab db&w’s exrTrader!
For a Description of Using OpenEXR in High End Nodal Compositing Apps Read Our 500+ Page Book: Creating a 3D Animated CGI Short
If you found this blog post interesting you’ll love my book: Creating a 3D Animated CGI Short, The Making of The Autiton Archives, Fault Effect – Pilot Webisode. This book is over 500 pages chock full of detailed examples and insights from the production of my 3D animated CGI short film – Fault Effect. It includes examples of every step of the production process; from initial concept through character design, set design, 3D modeling, texturing, lighting, camera animation, 3D character animation, lip sync, 3D rendering, post-production, compositing, and all the way to film festival submissions and online web distribution.
The book has a full chapter about Compositing, Editing, and Output using a node based compositor. In the book I used Shake, but the same approach is still applicable in current node based compositors such as Blackmagic Design Fusion, Nuke, Blender, Natron, Flame, etc. The chapter includes a detailed description of using OpenEXR high dynamic range renders to adjust and fine tune the exposure and lighting of your renders in post-processing which is much faster than trying to get the perfect exposure and lighting in-camera in the 3D rendering through endless render tests which is often very time consuming. Here are the relevant sections from the table of the contents.
Chapter 19: Compositing, Editing, and Output
- High Dynamic Range Compositing
- ILM’s OpenEXR HDR Format
- Node-Based Compositing
- The Anatomy of a Simple Shot Composite
- HDR Lighting Exposure Adjustment
- Adding Bloom to Enhance Lighting
- Adding Fog Effects with Z-Depth
- Enhancing In-Camera Depth-of-Field with zBlur
- Working with LightWave 3D Z-Depth Buffers
This comprehensive book also includes a companion CD-ROM with full color high resolution images from the book as well as many animated samples along with two of my full 3D animated CGI short films, Fault Effect™ and the award winning BlastOff!™ which screened at over 15 US and international film festivals.
This book is available on Amazon.com where you may browse it online.