-
1. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 1:59 AM (in response to deedeecz)If you convert to the much narrower sRGB space and save and close the file, BAM!, you lose the wider gamut—forever. Period.
If you don't close the file, then of course you can step back in History to a state before you discarded all those colors, i.e. before you did the conversion.
But why on Earth would you do something crazy like that?
Save a copy if you need a narrower space, do not convert your only original to a narrower profile. Additionally, I hope you have backup copies of all your files.
-
2. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:09 AM (in response to deedeecz)Your second question, the one about DNGs, cannot remotely be handled here in the same context.
The DNG format was conceived and designed for greater compatibility of digital camera raw files. Raw files are linear files, i.e., they are not in a color space at all.
PSDs, PSBs, TIFs, etc. do not contain any raw data at all, they are "cooked" and non-linear already, so why would you want them in a DNG wrapper?
Additionally, there is much more to the subject of DNGs because now there are such things as non-linear DNGs, compressed DNGs and even lossy DNGs, all of which you can discuss in the Adobe Digital Negative (DNG) Forum at:
-
3. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
deedeecz Jul 29, 2013 2:11 AM (in response to station_two)Thank you for such a prompt answer - I was about to do BAM!
I've just created a gigapanorama and used ProPhoto all the way and want to convert to sRGB for web use. I was just wondering if I could save some space and only have one (12GB) file instead of two. Well, I guess I'll just have to do "save as" and have two files.
So, the lossless conversion only applies to raw files?
-
4. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:28 AM (in response to deedeecz)deedeecz wrote:
…So, the lossless conversion only applies to raw files?
You need to elaborate. What "lossless conversion" are you referencing now?
You have at least two totally unrelated topics in this thread already, and I'm afraid this is a third one.
RAW files can be losslessly converted to losless raw DNGs.
Or it can be "losslessly" compressed or "lossily" compressed. Thatr is a subject you need to move over to the DNG forum. Personally, I don't have a need ot a use for DNG files, so don't know that much about them.
A cooked file can't be turned into a raw DNG anymore than you can "uncook" a fried egg and turn it back into a raw egg.
-
5. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
deedeecz Jul 29, 2013 2:30 AM (in response to station_two)I'm sorry, I didn't clarify - all I'm concerned about is color space conversion.
-
6. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:31 AM (in response to deedeecz)deedeecz wrote:
…I've just created a gigapanorama and used ProPhoto all the way and want to convert to sRGB for web use. I was just wondering if I could save some space and only have one (12GB) file instead of two…A 12 GB file on the web? ?? !! Even one 20 times smaller than that would be absurd on the web.
-
7. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:32 AM (in response to deedeecz)deedeecz wrote:
I'm sorry, I didn't clarify - all I'm concerned about is color space conversion.
Raw files have no color space at all.
-
8. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:34 AM (in response to deedeecz)Once you conver a raw file into any color space, it is no longer a raw file at all.
-
9. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
deedeecz Jul 29, 2013 2:43 AM (in response to station_two)Answer to 7:
Yes, I know, but if I open a .nef file which is has embedded Adobe RGB from the camera, then convert it to sRGB, SAVE, open again and convert back to Adobe RGB (or even ProPhoto) is it lossless in terms of color space?
-
10. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
deedeecz Jul 29, 2013 2:48 AM (in response to station_two)Ahhh, OK, I understand now. Forgive me, but I'm coming from Capture NX2 where you CAN convert color space and still be able to save as .nef
-
11. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 2:59 AM (in response to deedeecz)Nikon uses the ".nef" suffix—improperly so—for all kinds of things that are not really raw files at all but a particular flavor of TIFF.
Even some scans from Nikon scanners are often saved as NEFs but they are categorically NOT raw files at all, unlike NEFs from a Nikon digital camera, which are true raw files.
If it is no longer linear but in a color space with a gamma curve applied, they are absolutely NOT raw files, in spite of the .NEF suffix.
Digital Camera manufacturers suffer from delusions of adequacy when it comes to writing software.
-
12. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
deedeecz Jul 29, 2013 3:05 AM (in response to station_two)Thank you very much for exhausting and very educational answers!
-
13. Re: Converting TIFF from ProPhoto to sRGB and back - lossless?
station_two Jul 29, 2013 3:21 AM (in response to deedeecz)A raw file, before any conversion, is just a very, very dark grayscale file with nothing that the human eye could recognize as colors.
The algorithm that converts the file to a true color image, called demosaicing (also de-mosaicing or demosaicking) algorithm, "cooks" the file into a state where it can never be raw again.
It is an irreversible digital image process used to
reconstruct a full color image from the incomplete color samples output from an image sensor overlaid with a color filter array (CFA). It is also known as CFA interpolation or color reconstruction.
That is totally different from a color space or color profile conversion such as from ProPhoto RGB to sRGB. ProPhoto RGB is such a wide gamut that it contains even "invisible" or theoretical-only "colors".
There's a dedicated, separate and active Adobe Camera Raw forum at: http://forums.adobe.com/community/cameraraw?view=discussions

