|
Short answer - the ideal solution is to convert your source data into 16-bit (or higher) ProPhoto RGB as early as possible in your workflow, and use this for all your edits/storage. Convert to sRGB/aRGB as the final step, i.e. just before uploading the image to the print lab or posting online.
Long answer: sRGB should be obsolete because our consumer monitors, printers, and cameras can easily exceed its narrow gamut. However, since it's still widely used by non-colour management aware software (and people!), it's the de-facto standard online. However, many web browsers - even ones that should know better (I'm looking at you, Apple and Microsoft) - will ignore embedded colour profiles, so images for the web should be in sRGB.
Adobe RGB has a much wider gamut and seemed to be the colour space of choice for photographers in the past, e.g. when uploading to print labs, converting from camera RAW files, etc. However, it's also becoming obsolete because consumer equipment is starting to exceed its gamut. For example, monitors that advertise "97% of Adobe RGB" gamut usually also substantially exceed Adobe RGB in some parts of the spectrum.
ProPhoto RGB has a very wide gamut and is also widely used, though interestingly it still can't represent all of the visible colour spectrum. It's used by Adobe CS products internally, so for example in Lightroom if you open a RAW DSLR image (with edits applied) for editing in Photoshop, you'll notice that the default colour space is ProPhoto RGB.
I've attached a few images of gamut comparisons. In image #1, you can see how much wider ProPhoto RGB's gamut is, and how sRGB/AdobeRGB are readily exceeded (by a printer in this case). Image #2 shows the measured colour space of my archival pigment inkjet (solid) compared to Adobe RGB (wireframe) - the printer exceeds Adobe RGB in yellows/oranges, dark greens, and dark reds quite noticeably. Image #3 shows the measured colour space of my "99% AdobeRGB" desktop monitor compared to Adobe RGB - it can show pinks, reds, yellows, and greens well outside of Adobe RGB. I haven't profiled my DSLR/lenses yet, but others' results show that it's a wider gamut again than Adobe RGB.
The main downside of using a wider gamut colour space is that each shade-of-gray step in an 8-bit image represents a larger jump than it does for a narrower gamut such as sRGB. This means that your workflow needs to be at least 16-bits the whole way to ensure that you don't lose fine colour detail (compared with if you had used sRGB for editing). Unfortunately, JPEGs don't support 16 bits per pixel which often means storing DSLR images in TIFF or RAW format (with edits in metadata format, ala Lightroom).
For my own images, I edit in ProPhoto RGB for the whole workflow but convert to JPEG format with sRGB colour space for long term storage. My lifetime collection is already at 94 GB - of only "published" keepers, with no storage of RAWs or multiple sequence shots. It's definitely not ideal, but a smaller set of data is easier to "guarantee" longevity. (I keep my raw data on external drives, but I won't lose sleep if they die.)
Sorry for the long post - hope that helps!
|