Originally posted by biz-engineer Indeed, your experiment give some hint that raws aren't raws per say, it the file size isn't fixed. Interesting. Does it means the DNG could be read as a JPEG is the files header was modified to look like a JPEG?
It is still raw data, it is only further compressed. Many years ago, cameras didnt have compression, so the files were always exactly the same size, regardless of subject. In modern Pentax DSLRs, the data gets compressed. As you know, there are two types of compression: lossy, and lossless. This does not mean the original data gets changed, it is not the same as taking raw image data and turning it into a jpeg photo.
I think modern Tiff and Psd files also allow compression. This doesnt mean the Dng contain wrong data, just that the data gets compressed for recording. It just means that the Dng container allows some modern technologies like compressing data to reduce the space it takes.
That said, I think tests have shown that pretty much all modern DSLRs have some level of raw-cooking (regardless of compression, as this happens before compression). The question is just how much. I think Pentax has a really low amount of this, compared to, for example Sony. I havent seen this type of analysis done on the K-1 yet