[Dabhand16]

Dave - Here are two versions of a picture, the first with Adobe RGB colour space, the second with sRGB. The only tweak from the originals posted in the other thread is a slight gamma change in levels to darken it slightly. When I assigned the sRGB colour space, the image displayed in PS noticeably changed, but here the difference appears minimal.

Adobe RGB



sRGB



Edit: After some more viewing on here and in PS, I think the sRGB one is more muted than the Adobe RGB

[JMitchell]

Really? On my monitor, the sRGB one looks much less flat...

[Dabhand16]

When I switch from Adobe to sRGB the image does loose tonal range. Must be my eyes Jack. I am a bit colour blind so that does not make it any easier.

[Dave]

If I open your original shot from the other thread, in Photoshop it shows as "Adobe RGB (1998)" . If I now go "Edit" -> "convert to profile" & select destination profile as "sRGB - IEC61966-2.1" there is no change in appearance on the screen.

Are you changing profile in the same manner Graham ?

[Dave]

Example shot from anpother thread on subject, the difference saving a JPG withou converting form RG to SRGB 1st here :- sRGB or Adobe 1998

[silkstone]

I'm not very regular here these days and I don't want to start a war , but I reckon this sRGB versus Adobe RGB (aRGB) causes more confusion than anything.

(Almost) nothing can display or reproduce the aRGB gamut except some photo printers. Everything you see on the web or on your monitor is limited to sRGB. Some high-end graphics monitors can exceed sRGB, but not normal ones.

The aRGB gamut includes some colours - especially intense cyans and magentas - which cannot be displayed under sRGB, but you won't see these except on prints from aRGB-capable printers. Commercial prints (Photobox etc) don't usually print outside the sRGB gamut.

Anything displayed on the web, or in an application that isn't colorspace aware, should be converted to sRGB or the colours will not be correct. Windows does not natively recognise anything other than sRGB, and neither do Office applications. You have to use a colorspace-aware app such as Photoshop to display aRGB correctly.

Apart from the potential confusion of having images in different colorspaces for different purposes, is there any drawback to aRGB? After all, you are retaining colours which, although they cannot be displayed, may still be printable.

Well, there may be. Each colour channel (Red, Green, Blue) is divided into 256 steps in an 8-bit-per-channel image. Every hue is defined by a code of three numbers, but the same numbers do not define the same colours in different colorspaces. If you increase the gamut, you are spreading the steps in each channel over a wider range, so the difference between adjacent steps will be greater. This may lead to a greater risk of posterisation or blocking, especially if you stretch the tones in post-processing. That's one reason why 16-bit processing is more important in aRGB than in sRGB.

There is therefore an argument for using a colorspace that doesn't exceed the limits of whatever you are using to display or print the image - so none of the data steps are wasted.

If you want to go the whole hog you can use ProPhoto RGB which has a huge gamut - much greater than either sRGB or aRGB - but the trouble is that nothing can reproduce those extra colours. However, some applications (including Lightroom and PS) use ProPhoto as their native colorspace, although this works in background so you're not usually aware of it.

Apologies if this is a bit of a ramble, and honestly I'm not trying to be controversial. I do believe that sometimes the effect of using different colorspaces is misunderstood or exaggerated, so I hope this helps to clarify.

[Charlotte]

Exactly my view, silkstone

I did recently try Prophoto in Lightroom, just to see, but it was a disaster! Here's what happened ...

I edited an image in Lightroom + exported it as a jpg using the Prophoto colour space. It looked wonderful in the Windows Explorer preview .......

I then opened the image in PhotoPlus to edit finishing touches ... but it looked completely different and, I have to say, awful! So I had to edit it all over again in PhotoPlus to get it how I wanted it. Again.

Guess who immediately switched back to exporting into sRGB

[silkstone]

Cheers Charlotte.

A couple of other things I forgot to ramble about....

One is that RAW files do not have a colorspace attached. You choose the colorspace when you convert/save/export them, so you can always go back and re-convert to a different colorspace using the same edits.

The second is pretty obvious and is that the additional gamut of Adobe RGB is only any use if the subject/image actually contains the extra colours. Unless you're into vivid magentas and cyans, it may not.

Oh and there's another one.... The colorspace diagrams that show what you get/lose in sRGB/aRGB etc can be a bit misleading. They show all these colours and then have a boundary to indicate what the different colorspaces can display. The fact that you are seeing these diagrams in sRGB on the web (or on your monitor) means that sRGB can display absolutely all the colours you can see!

[Dabhand16]

Originally Posted by Dave

If I open your original shot from the other thread, in Photoshop it shows as "Adobe RGB (1998)" . If I now go "Edit" -> "convert to profile" & select destination profile as "sRGB - IEC61966-2.1" there is no change in appearance on the screen.

Are you changing profile in the same manner Graham ?

Yup. And when I do that - there is a noticable change - to my eye for the worse - but when I see them together, the difference seems less noticable.

[Dabhand16]

Here are another two. Again, when I switched to sRGB, the image became noticably cooler, and when I looked at the thumbnails in the folder it was really noticable too.

Interestingly, I find the difference here is again, minimal, but this time I think the sRGB one has the edge.

Adobe RGB:



sRGB:

[Charlotte]

Originally Posted by silkstone

... RAW files do not have a colorspace attached. You choose the colorspace when you convert/save/export them, so you can always go back and re-convert to a different colorspace using the same edits.

Yes, I could've done that!

Originally Posted by silkstone

Oh and there's another one.... The colorspace diagrams that show what you get/lose in sRGB/aRGB etc can be a bit misleading. They show all these colours and then have a boundary to indicate what the different colorspaces can display. The fact that you are seeing these diagrams in sRGB on the web (or on your monitor) means that sRGB can display absolutely all the colours you can see!

I don't think the assumption in your last sentence is exactly correct silkstone ... if certain colours of any image, including colour space diagrams, are not within the realm of the gamut that your display is using (sRGB) then it will render those colours incorrectly. You may think you're seeing the diagram (or other image) in its correct form, but I believe the colours which are outside of sRGB's capabilities will be displayed to the nearest colour.

[silkstone]

What I was trying to say is that all the colours you are actually seeing on your screen are visible in sRGB because that's the colorspace you're using to view them.