What are Uncompressed RAW, Lossless Compressed RAW, or Compressed RAW image files and when should I use each type?

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RAW files are image files that can contain uncompressed and unprocessed image data, allowing you to capture practically every detail seen from the camera image sensor. Compression in photography is the process of reducing the size and quality of your photos. There are several reasons photographers opt for compression, with the most common being to optimize camera storage space.

There are three types of RAW image files that will result in different file sizes based on the type you choose:

• Uncompressed RAW:
  • An uncompressed RAW file preserves all of the data in an image without compression.
  • As all image data is stored with no impact on quality, you have the freedom to manipulate aspects of the photo like brightness, color, sharpness, and noise reduction with minimal quality loss.
  • Recommended when both high image quality and developing speed are required, as this format can be developed more quickly by development software than Lossless Compressed RAW.
  • It is the largest RAW image file size.
• Lossless compressed RAW:
  • Lossless compression is a popular format that allows you to reduce image size without compromising on quality.
  • A lossless compressed image is processed by post-processing software and the data is decompressed like a ZIP file. Decompression allows you to expand the compressed file back to its original size.
  • Recommended when you want to record with the same image quality as Uncompressed RAW but with a smaller file size for storage considerations.
• Compressed RAW:
  • Compressed RAW, also known as lossy compression, is a format that reduces the data in a photo.
  • An image captured in Compressed RAW occupies less storage space.
  • Once an image is stored in a Compressed RAW format it cannot be decompressed, meaning that the image will lose some of its data.
  • This format is recommended when you want to shoot continuously at the maximum speed or limit the file size.
  • It is the smallest RAW image file size.