Render Output Format

Render output formats refer to file formats used to store the final render output of a scene. This can either be in an image format, or video format.

Recommendations

For the vast majority of cases, it is recommended to save the render output in an image based format, as the extra complexity of video formats can cause corruption issues in the middle of a render. In addition, memory issues during a render for animation can also cause individual frames to be corrupted with their output, which for single images is easier to fix with a simple re-render.

In terms of image formats, lossy compression is generally discouraged, as a large amount of information and quality is lost in the compression process. In cases where heavy post-processing is not needed, common formats include PNG and TIFF. In cases where heavy post-processing is needed, EXR is recommended, as the extra information stored in each pixel allows for much more flexibility. It should be noted however that tonemapping isn't baked into EXR outputs, so tonemapping will need to be performed in any later programs used for post-processing. As EXRs store much more information compared to other formats, lossy compression algorithms such as DWAA can be used to reduce image sizes, without losing as much in quality compared to JPEG.

In situations where file sizes need to be reduced (such as posting on the internet), it's best to first output to a file format of a high quality (e.g. PNG, TIFF, EXR, etc.), then convert the high quality image to a lower quality image, or to a format with lossy compression and low file sizes (e.g. JPEG, WebP, JPEG-XL, etc.). The main benefit of this approach is being able to convert to multiple images of varying qualities from one, high quality source image, either for the purposes of experimentation or for having different qualities for different purposes (e.g. thumbnails, banners, profile pictures, etc.). In addition, for animation, having a high quality image sequence allows for more flexibility with the final video file, allowing for easily switching between different codecs (e.g. H.264, H.265/HEVC, AV1, etc.), adjusting bitrate, etc.