The Canon sRaw and mRaw Output Formats
Douglas A. Kerr · 2014
Many digital cameras (including many Canon models) offer an optional form of output file in which the data does not directly represent a “finished” image but rather is a more-or-less verbatim transcript of the digitized output of the collection of individual sensor photodetectors. This is referred to as the “raw” output. Recent middle- and upper-tier Canon dSLR cameras offer an alternative to this output file type, described as the “sRaw” (“small raw”) output, and in current cameras a variation of that as well, called “mRaw” (“medium raw”). In this article we first discuss the principles of the sensor arrangement that leads to the use of the raw output concept. Then we briefly review the “regular” raw output, what we do with it, and the advantages of operating in that mode. Next we describe the concept of the sRaw format, its important technical details, and why it is said to be beneficial. Finally, we introduce the mRaw format, and compare it with sRaw. BACKGROUND The matter of “raw” output formats is heavily influenced by the nature of the CFA (color filter array) sensor used in most modern digital still cameras. We begin with some background on that. Tristimulus pixel sensors