It's not.
a) compression can be lossless.
b) RAW is not about storing literal photons ADC measurements. It always has "some" processing as those always go through an ISP. We can obviously discuss which processing is the cutoff point and it will differ for different applications, but typically this would include things like clipping, sharpening, or denoising. And even some pro DSLRs would remove row noise or artifacts in supposedly "RAW" files!
If you can change the exposure or WB - it is what is the minimum practical/useful definition of a RAW.
>If you can change the exposure or WB - it is what is the minimum practical/useful definition of a RAW.
No. No it is not at all. Are you a photographer? I am not talking about processing before the photo is saved, I am talking abot the compression of the save file.
Are you trying to tell me that these are the same?
RAW
"A camera raw image file contains unprocessed or minimally processed data from the image sensor of either a digital camera, a motion picture film scanner, or other image scanner. Raw files are so named because they are not yet processed, and contain large amounts of potentially redundant data"
JPEG-XL
Lossless compression uses an algorithm to shrink the image without losing any IMPORTANT data.
Lossless compression is not about importance of data. Lossless is lossless, if the result of a roundtrip is not EXACTLY IDENTICAL then it is by definition not lossless but lossy.
Maybe you're confusing with "visually lossless" compression, which is a rather confusing euphemism for "lossy at sufficiently high quality".
JPEG XL can do both lossless and lossy. Lossless JPEG XL, like any other lossless image format, stores sample values exactly without losing anything. That is why it is called "lossless" — there is no loss whatsoever.
Yes, I am an (amateur) photographer for the last 27 years, from film, DSLRs, mirror less, mobile. And I worked on camera ISPs - both hardware modules, saving RAW files on mobile for Google Pixel, as well as software processing of RAWs.
"Lossless Compressed means that a Raw file is compressed like an ZIP archive file without any loss of data. Once a losslessly compressed image is processed by post-processing software, the data is first decompressed, and you work with the data as if there had never been any compression at all. Lossless compression is the ideal choice, because all the data is fully preserved and yet the image takes up much less space.
Uncompressed – an uncompressed Raw file contains all the data, but without any sort of compression algorithm applied to it. Unless you do not have the Lossless Compressed option, you should always avoid selecting the Uncompressed option, as it results in huge image sizes."
Why make the distinction if there is no difference?
Apple is COMPRESSING the image. Period. RAW photos can be compressed, but if they are then they are "RAW Compressed" Files, not "RAW" files.Apple is not saying you are shooting RAW Compressed, it says you are shooting ProRAW photos, which is slick marketing because everyone thinks they are shooting RAW photos but ProRAW is not RAW. The iPhone 12 gave you a choice to shoot RAW or ProRAW, but my iPhone 13 ProMax only allows the ProRAW option. I have no option to avoid Apple processing my photos anymore.
It is semantics but words matter. If something is off with the compression algorithm or the processing how would you know?
More, if the difference did not matter, why does Sony go out of the way to explain the difference?
If a computer compresses and expands the image using an algorithm you are not getting back the same image. Period. I do not care if you perceive it to be the same, it is not the same.
> Why make the distinction if there is no difference?
There is a difference, which is that the compressed lossless version is smaller and requires some amount of processing time to actually be compressed or uncompressed. But there is zero difference in the raw camera data. After decompression, it is identical.
> If a computer compresses and expands the image using an algorithm you are not getting back the same image. Period. I do not care if you perceive it to be the same, it is not the same.
It is the same. You can check each and every bit one by one, and they will all be identical.
No, but it’s also a painting instead of a digital file, so different considerations apply (maybe the copy wouldn’t be strictly identical, maybe the value is affected by “knowing that Van Gogh is the one who applied the paint to the canvas” or by the fact that only one such copy exist), and this is therefore a false analogy.
If you copy the number written on a piece of paper to another piece of paper, is it the same number? Yes, it is, and a digital photograph is defined by the numbers that make it up. Once you have two identical copies of a file, what difference does it make which one you read the numbers from?
Or are you arguing that when the camera writes those numbers to the raw file, it’s already a different image than was read from the sensor? After all, they were in volatile memory before a copy was written to the SD card.
If you can change the exposure or WB - it is what is the minimum practical/useful definition of a RAW.