Compression for Raw Captures


Today’s Question: For raw captures do you recommend lossless compression or uncompressed, and would there be a quality difference between the two?

Tim’s Quick Answer: In general, I recommend using the lossless compression option for raw captures if your camera supports this, as it can significantly reduce file size without degrading image quality.

More Detail: Some cameras offer options related to the raw capture format in terms of whether compression is applied. With some cameras you can even choose between lossless compression and lossy compression.

Lossless compression operates by recording image data more efficiently, resulting in smaller file sizes. This compression does not alter the original capture data, it simply encodes the data in a way that requires less storage space. This enables you to take advantage of the benefits of raw capture while being able to store more images on a given media card. The only real drawback is that the compressed raw captures will be a little slower to process because the data needs to be decoded as part of that task. In general, you would not likely notice a significant performance issue related to lossless compression.

Lossy compression, on the other hand, further reduces file size by altering the original capture data to some extent. While this compression is generally of very good quality, there is some loss of fidelity. Out of an abundance of caution when it comes to maximizing image quality, I don’t recommend using lossy compression for raw captures.

Uncompressed raw captures could be a little faster to process when optimizing the image, but the file sizes will be considerably large than with a raw capture with lossless compression applied. Therefore, I prefer lossless compression for raw captures, but I would acknowledge that using uncompressed raw is the more conservative approach.