adobe rgb v srgb

[shutternutter]

hi everyone!
i just joined, cause this seems like a great place to get advice for newbies. I bought a dslr a few months ago and am still getting to know it. looking forward to becoming a proper member and getting to know u all!

so, to my point in question that led me here in the first place: this
http://www.cambridgeincolour.com/tut...obeRGB1998.htm
article says to use adobe rgb by default for 16bit images and srgb for 8bit. since i use 24bit, i assume adobe would be the way to go (by default, not always of course). is that so?

[george013]

hi everyone!
i just joined, cause this seems like a great place to get advice for newbies. I bought a dslr a few months ago and am still getting to know it. looking forward to becoming a proper member and getting to know u all!

so, to my point in question that led me here in the first place: this
http://www.cambridgeincolour.com/tut...obeRGB1998.htm
article says to use adobe rgb by default for 16bit images and srgb for 8bit. since i use 24bit, i assume adobe would be the way to go (by default, not always of course). is that so?

16 bit is per channel. 8 bit is per channel. 24 bit means 3x8, so 8 bit per channel. There's also 32 bit and that's 8 bit pere channel too: monitors.

George

[shutternutter]

ha! lots left to learn...

thank you!

[Manfred M]

Welcome to CiC.

Would you mind clicking on the "My Profile" button at the top of this page and adding at least your first name and where you are from to your profile information?


Just to add to George's comments:

1. AdobeRGB can reproduce more colours than sRGB can. Generally, having more colours tends to be good, especially if shooting very vivid greens. That being said, this may not make much difference to you because most colour computer screens are not AdobeRGB compliant, so you might not be able to take advantage of the colours. It becomes more important when one starts editing the images.

Adobe RGB can reproduce about 1/2 of the colours humans can see while sRGB can only reproduce about 1/3 of the colours we can see.


2. The "standard" used by most web sites is sRGB, so in general it is advisable to convert the image to sRGB when posting to the web. Not all browsers handle colour spaces all that well and AdobeRGB colours will look muddy when posted on some web browsers.

In general, if one shoots in AdobeRGB one should convert the image to sRGB before posting to the web.


3. Higher bit depth allows many more colours to be used. This is especially important in editing work as editing 8-bit files can lead to editing "artifacts" where strange blocks or bands of colours can show up. This tends to be much less of an issue when working in 16-bit.

Most people post JPEG files which tend to default to 8-bit.

[xpatUSA]

What's interesting about "Adobe RGB" or more correctly, Adobe RGB (1998), is that the primaries apparently arose as a series of mistakes:

https://en.wikipedia.org/wiki/Adobe_...cal_background

Then the red, blue primaries and the white reference are exactly the same as those for sRGB! Meaning that the oft-quoted "wider gamut" is in the direction of green. Not only that, if the gamut is being shown in CIE x,y,Y space (the 1931 horseshoe) that wideness is exaggerated because similar color differences look bigger - especially in the green area.

To see the "real" difference between the two, please refer to the perceptually uniform CIELUV representation of their gamuts.

For myself and the avoidance of round-trip errors, etc, I edit in floating-point ProPhoto which is RawTherapee's default mode.

Sorry, Melissa,

[Manfred M]

If you dig a bit further, the reason that kicked off AdobeRGB at Adobe was an attempt to find a better way of matching what the photo editors saw on their computer screens of the day versus what they were seeing coming off the offset printing presses. Most of the Adobe commercial customer base of the day used this workflow to produce magazines, catalogues, etc.

Nicely said, they were looking for a way of mapping RGB screen colours to CMYK press results. My understanding is that this goal was not achieved all that well, but Softproofing, which was introduced in Photoshop 6 (not CS 6) in 2000 was a direct outcome of that work.

The mistakes that were made and attempts to correct them are "legendary" in Photoshop folklore.

[shutternutter]

thanks manfred and ted!
I'm starting to get it, i think. i suppose at least for now I'll stick to srgb, since for the time being my shots don't make it to the analogue world anyway...

[billtils]

Max

There will be very few, if any, observers who could look at a single image and tell whether the photographer was working with srgb or Adobe RGB (1998). If your end point is viewing at home on a monitor then there's no point in getting concerned about what is the better. However, if your end point includes prints that are being produced for you by a commercial print shop then you should review their requirements - some will specify srgb others the Adobe. Likewise if you have any thoughts about extending your hobby to include membership of a club and participation in their competitions, you will probably find that they will specify one or the other.

[pnodrog]

thanks manfred and ted!
I'm starting to get it, i think. i suppose at least for now I'll stick to srgb, since for the time being my shots don't make it to the analogue world anyway...

Provided that you archive and keep your photo files sometime in the future one of them may end up being very important to you and you could regret not having used the widest colour space available. The same goes for size and quality (jpeg).

As your editing skills progress you may well be able to successfully use an early photo that you initially ignored. Adobe RGB will give you a little more leeway when editing.

For future proofing size and quality is more important than colour space but it pays to save in the best and widest options you have. Storage is amazingly cheap nowadays.

[shutternutter]

That's actually a very good point, Paul, also in view of what Bill said. Who knows what the future holds and what I might want to do with my photos then

[Manfred M]

That's actually a very good point, Paul, also in view of what Bill said. Who knows what the future holds and what I might want to do with my photos then

If you really plan to do this, then you might decide to set up your camera the same way I shoot; JPEG + raw.

That way you have both an image you can use today, with the knowledge that you currently have but still save all the data that your camera collected (likely in 14-bit) for the time that you might want to use an even wider colour space to reproduce your image. The main penalty is that this takes up a fair bit of hard disk storage on your computer. If you have lots and back up your files externally (always a good practices, as all computer disks will eventually fail), you can revisit and edit using a wide gamut colour space like ProPhoto, rather than sRGB or AdobeRGB. ProPhoto can reproduce over 80% of the colours people can see.

[DanK]

If you really plan to do this, then you might decide to set up your camera the same way I shoot; JPEG + raw.

That way you have both an image you can use today, with the knowledge that you currently have but still save all the data that your camera collected (likely in 14-bit) for the time that you might want to use an even wider colour space to reproduce your image. The main penalty is that this takes up a fair bit of hard disk storage on your computer. If you have lots and back up your files externally (always a good practices, as all computer disks will eventually fail), you can revisit and edit using a wide gamut colour space like ProPhoto, rather than sRGB or AdobeRGB. ProPhoto can reproduce over 80% of the colours people can see.

Max,

You never said whether you are shooting JPEG (letting the camera convert the raw image into a viewable JPEG image) or raw. If you are shooting JPEG, there are more reasons than the one Manfred gave to shoot raw+JPEG. Raw gives you more flexibility in editing, even leaving aside the wider color space. For example, a raw file has no white balance baked in, so you can easily correct white balance even if your camera setting was far off. If you are now shooing JPEG and switch to raw+JPEG, you can always go back and edit the raw files yourself at a later date.

[xpatUSA]

I can not help but feel that side-car files could play a role in this discussion, but they haven't been mentioned yet.

For example, my editor saves a side-car file with the originally-opened-for-editing file (raw or not). Optionally it also saves a side-car file with the edited and exported image file - wherever it goes to. That means any further edits applied to the original are saved with the original, but not with the previously exported file. So that provides a sort of tracking mechanism for individual exports.

Could that be useful, I wonder?

[shutternutter]

hi guys!
sorry i've been quiet for so long, had a string of visitors over. luckily, that also gave me the opportunity to shoot a lot and now i know that even my awful old laptop can display adobe just fine.
as to your questions, when i switched to adobe i also switched to raw+jpg, or really the other way round. the only reason i hadn't used raw before was that somehow neither photoshop nor my image viewer can handle the cr2 files my camera produces. i now got a converter from canon that will hopefully do the job.
i also switched becasue on some more extreme edits jpeg artefacts became too obvious, which ruined a few nice shots...
haven't had a chance to actually edit anything yet, because said old laptop has an awful screen with a yellow tint. really need to get my desktop pc over, can't wait to edit

[shutternutter]

I can not help but feel that side-car files could play a role in this discussion, but they haven't been mentioned yet.

For example, my editor saves a side-car file with the originally-opened-for-editing file (raw or not). Optionally it also saves a side-car file with the edited and exported image file - wherever it goes to. That means any further edits applied to the original are saved with the original, but not with the previously exported file. So that provides a sort of tracking mechanism for individual exports.

Could that be useful, I wonder?

i actually always keep psd files with the adjustments as layers, so i can adjust later on. it happens often enough that the next morning i notice my edit was off...
i guess that's more or less what you're talking about?

[xpatUSA]

Originally Posted by xpatUSA I can not help but feel that side-car files could play a role in this discussion, but they haven't been mentioned yet.
<blah>
Could that be useful, I wonder?

i actually always keep psd files with the adjustments as layers, so i can adjust later on. it happens often enough that the next morning i notice my edit was off...

i guess that's more or less what you're talking about?

I don't use Adobe products, Max, so I have no experience with the PSD file format but that does sound similar to what I was talking about.

[Manfred M]

I don't use Adobe products, Max, so I have no experience with the PSD file format but that does sound similar to what I was talking about.

Ted - a PSD file is fairly similar to a TIFF file in terms of both format and content. As it is an image file, it requires that both the colour temperature and colour space data and that is "baked" into the image file. In fact quite a few photographers do store their final Photoshop edits as TIFF files. This gives them the opportunity to edit these files in the future, should they end their Adobe subscription and move to a different pixel based editor. The only disadvantage to the TIFF format is that the files tend to be a bit larger than PSD and, so far as I understand it, not all of the edit information in a PSD can be stored in a TIFF. I have not experimented here, but suspect Adobe SmartObjects, especially as it applies to filters might be one area of incompatibility.

The sidecar file is a lot more flexible that way as these two parameters are stored in either a side-car file or in a database (catalogue for the Lightroom and Capture One users). As these values are not "baked-in", they can be changed at any time.

[xpatUSA]

Ted - a PSD file is fairly similar to a TIFF file in terms of both format and content. As it is an image file, it requires that both the colour temperature and colour space data and that is "baked" into the image file. In fact quite a few photographers do store their final Photoshop edits as TIFF files. This gives them the opportunity to edit these files in the future, should they end their Adobe subscription and move to a different pixel based editor. The only disadvantage to the TIFF format is that the files tend to be a bit larger than PSD and, so far as I understand it, not all of the edit information in a PSD can be stored in a TIFF. I have not experimented here, but suspect Adobe SmartObjects, especially as it applies to filters might be one area of incompatibility.

The sidecar file is a lot more flexible that way as these two parameters are stored in either a side-car file or in a database (catalogue for the Lightroom and Capture One users). As these values are not "baked-in", they can be changed at any time.

Thanks for the info, Manfred.

I remember using Elements 6 which came with ACR (4.5?) and the opportunity was there to "save" raw files along with their .xmp side-car files. By renaming them, I could save several side-car files for the same raw file .

Adobe 'XMP' format being a sub-set of XML, those files are also editable in most HTML editors, for what that's worth.