A camera RAW file contains uncompressed and unprocessed data (pixels) obtained from the camera’s sensor at the time of exposure, along with image metadata—unique information about how the image was captured. All types of camera RAW images—Uncompressed, Lossless Compressed, and Compressed Lossy—can be adjusted, edited, and processed in software such as Adobe’s Camera RAW Editor or Capture One. A RAW editor allows you to adjust all RAW images while preserving the camera RAW data and saves your edits and adjustments as metadata associated with the original file.
Differences Between a RAW File and a JPEG?
RAW files and JPEGs are fundamentally different. JPEGs do not contain all the original data captured by the sensor, while RAW files do. JPEGs are processed and compressed by the camera at the time of capture, whereas RAW files are not. JPEGs can be made from RAW files, but RAW files can never be made from JPEGs. Additionally, RAW files are significantly larger than JPEGs, requiring more storage space and longer transfer times from camera to computer during tethering. The beauty of the RAW file is its preservation of all data captured by the sensor, although this results in larger file sizes. This is where compression becomes beneficial.
Understanding RAW Compressed Lossy, RAW Lossless Compressed, and RAW Uncompressed?
- RAW Compressed Lossy: A reduced file size where not all original image data is preserved; some data is deliberately eliminated during compression. This can cause visible image artifacts, depending on the camera make and model, as well as subject matter and lighting conditions during capture.
- RAW Lossless Compressed: A reduction in file size without any loss of original data, similar to a ZIP file. The actual file size reduction depends on the camera make and model, with some cameras achieving a 20-40% reduction.
- RAW Uncompressed: No compression, preserving all original data and resulting in a large file size.
Most Common Use Cases for Shooting Compressed RAW Files
Compression reduces RAW file size, allowing you to:
- Write to the card and transfer images to the computer faster—whether tethering with a cable or over Wi-Fi, smaller files transfer more quickly.
- Save storage space and money—smaller files require less space on camera cards and external drives.
- Increase continuous shooting time—smaller files take up less buffer space (depending on the camera).
- Reduce computer processing time—smaller files process faster, streamlining workflow.
We recommend choosing the smallest image quality size necessary for your shoot, balancing client requirements, final image needs, the type of tethering (cable or Wi-Fi), and your camera’s file capabilities.
Refer to your camera’s user manual or the manufacturer’s website for more information about your specific camera.
