Hi,
Most vendors use some version of
"Huffman coding". Huffman coding is lossless, so the uncompressed image can be reconstructed bit for bit.
This is quite different from a compression scheme like the one used by Sony, which used a tone curve type of approximation taking shot noise into account. With such coding the image can not be reconstructed bit for bit, but no real information would be lost as all information deposed of would be masked by shot noise. Shot noise is the natural distribution of photons reaching the pixels.
To that Sony added a "delta type" compression which saved min and max values for 16 pixels and represented with just 7 bit coding. That compression could cause artefacts over edges having very high contrast and that has been demonstrated in some cases.
So you can have reversible compression, like Huffman. Or virtually lossless like the Sony tonal curve or a compression with artefacts like the Sony delta coding.
I guess that if Fuji talks about lossless compression it is "Huffman coding". A more efficient coding is LZW, but I don't think it is commonly used in camera raw files.
Best regards
Erik
I love my new Fuji X T-2 and have looked in some detail at a variety of images, with both shadow and highlight detail. I am unable to tell the difference between those made without compression and those made with "lossless compressed." The manual refers to a "reversible algorithm," with no loss of data. While storage is inexpensive, I still would like to conserve space, and presumably speed up processing in Lightroom and Photoshop. But I will not tolerate quality loss. In my Nikon D800E era, I always used uncompressed RAW files, possibly just from stubbornness and a belief (not founded on expertise of any kind) that there's always a cost to compression. I used the "if it sounds too good to be true..." argument.
Has anyone who might have more expertise than I do in terms of image quality looked at this issue? I suspect I am not the only one with this question.