Raw and Log: The Superior Recording Formats
Raw and Log formats are used to achieve similar desires within video, including higher quality, a greater dynamic range, and more control in post-production. Although both formats allow for similar results, raw and Log recording is not the same.
A raw file is sensor data, not video. Raw data is the information, or ones and zeros, that is produced from light hitting a camera’s image sensor. The raw data has not yet gone through the further processes that convert the data into video. Raw footage has a higher bit depth and dynamic range, or the amount of tonal detail from the darkest (shadows) to the brightest (highlights) parts of an image. Information like ISO, white balance, and color adjustments have not been baked into the raw data yet, allowing for much greater manipulation in post-production. Since raw data is unprocessed and has only been extremely minimally compressed, the file size is very large.
Log is a video format that manipulates a gamma curve to prepare the video for maximized grading in the post-production process. The image appears to be very flat and desaturated, but once grading is applied the possibility for rich gradation and details in highlights and shadows exists. The dynamic tonal ranges of footage are increased with a Log format. Shooting Log gives a similar result to raw recording, but with slightly smaller files and no need for conversion with monitor playback. Depending on the camera manufacturer, Log formats have variation in technology and brands. For example, Sony uses S-Log, Canon uses C-Log, and Panasonic uses V-Log.
Shooting in raw or Log is superior to other recording formats such as H.264/265 or AVCHD due to the ability for a higher dynamic range, bit depth, capturing of detail, and freedom in post-production. H.264/265 and AVCHD file formats are extremely compressed when compared to raw, or even Log, files. The H.264 file format, for example, has lossy compression while raw data remains untouched by a codec. Compression gives loss of quality in both sharpness and color depth. If H.264 is color graded in post-production, the highlights are clipped very quickly and the shadows are undesirably crushed. In fact, color grading an H.264 file is like color grading a file twice. When H.264 footage comes from the camera, color adjustments, white balance, and ISO are already baked in, like a color grade that has already been applied.
Raw and Log technology would be chosen for a production due to its high quality and dynamic range. As mentioned earlier, huge flexibility in post-production is a major argument for using raw and Log formats. This can help with mistakes that were made during production and provide creative solutions to environments that were hard to shoot in. Log and raw formats also allow a new white balance and ISO to be adjusted after the fact. During production, raw and Log technology works best in situations that have a lot of detail and texture, for example filming a nature scene full of rocks and leaves. Due to their wide dynamic range, Log and raw technologies are very successful in situations that both have bright highlights and dark shadows. For example, Log and raw technologies would be able to shoot a scene of the interior of a house and then look through a bright window to the exterior with smooth gradation, unlike H.264/265 or AVCHD file formats. If a production is taking place in an area with high contrast in brightness and a lot of detail, raw or Log should be used for the best possible image.
A production may choose not to use this Log or raw technology during production because of expense. Since Log and raw formats have much larger file sizes than H.264/265 or AVCHD and require high-performance hardware, cameras with the ability to shoot Log and raw are more expensive. For raw data, a production will need to spend more money on storage and transcoding, editing, and coloring software. Also, depending on the production’s computer type, it might not be strong enough to handle a raw workflow. When recording Log, using an external recorder to capture the full potential of the footage is recommended, but an external recorder adds another expense to production. Shooting in low light is also not ideal for a Log format. With a dark or night scene, using Log does not allow for enough data to properly be recorded and any noise in the image will be noticeable. Raw or Log also should not be used when a production has a fast turnaround time. In order for the footage to look correct, proper coloring and processing needs to occur which adds extra time to a production. Filming a wedding, studio work, or green screen also may not require shooting raw or Log due to controlled lighting. In these situations, shooting raw or Log can add more time and work spent in post-production than is necessary.
If shooting in a raw or Log format, viewing the image on a monitor while in production becomes a bit more complicated than if shooting in a H.264/265 or AVCHD style format. Since raw is simply data, rather than video, the raw data itself cannot be viewed on a monitor successfully. Instead, a camera with raw capabilities will convert the raw data into a familiar video format, such as H.264/265, AVCHD, or even Log, for monitoring purposes. Although a conventional video format is used for monitoring, the data recorded is still raw.
Unlike raw, Log is already a video format and data conversion is not required for Log monitor display. While it is “easier” for Log to be viewed on a monitor, the Log recording appears to be very flat. External monitors often have the ability to view a LUT on the recorded footage for a preview of what an applied LUT, or Look Up Table, will look like in post-production. For aesthetic purposes, LUTs take the flat and washed out footage and apply detail and saturation, emphasizing the dynamic range that is able to be captured through shooting Log. Using a LUT preview on an external monitor helps to satisfy the client’s want for pleasing footage and confirms that the exposure is reasonable from shot to shot. Even when converting raw data into a Log format for monitoring, a LUT still needs to be applied to the recorded footage in order to eliminate the flat look.
Although raw and Log tend to have larger file sizes, shooting in raw or Log is superior to other recording formats due to the greater dynamic range and manipulation allowed in post-production before the loss of detail occurs.