Recommendation on Compressed Raw


Today’s Question: Do you recommend RAW or cRAW capture, with high resolution cameras such as the Canon R5, in fast action wildlife using servo with high frame rate?

Tim’s Quick Answer: While the Canon compressed raw (cRAW) provides very good quality with file sizes that are about half that of uncompressed raw captures, in the case of Canon’s cRAW the image data is compressed with a lossy algorithm that can result in reduced image quality and increased noise.

More Detail: Various cameras offer compression options for raw capture. That can be lossless compression that preserves image quality, or lossy compression that results in some degree of image degradation. In the case of Canon’s cRAW option, the compression is lossy.

The benefit of this lossy compression is that file sizes are greatly reduced. With the Canon cRAW format for example the file size is typically about half that of an uncompressed raw capture.

The drawback of lossy compression for a raw capture is reduced image quality. To be sure, this is generally extremely minimal. However, I have seen loss of quality in dark shadow areas and increased appearance of noise as side effects of the compression.

Personally, I would be comfortable using a lossless compression raw format if storage space were the priority. I prefer not to use raw captures with lossy compression. The results with lossy compression are still very good, but in my mind part of the reason for using raw capture is to ensure optimal image quality, and I’d prefer not to risk degrading that quality right at the time of capture.