Colour shifts on Pbase.

[igas]

Hi all,

The below screenshot shows a side-by-side comparison of a photograph which I recently posted on pbase.

I cannot understand why there appears to be a colour shift. (Look particularly at the red shirt.) Did any of you ever notice this on their uploads to pbase? Obviously there is nothing I could have done to change anything in the file from the moment I hit the upload button. Independetly of whether which colours are "correct" or not; pbase is not displaying what I see in PS.

I checked a few of my older postings and none of them are exactly as seen in photoshop. The problem seems to lie mainly with the reds.

Picture taken using 10D, 17-40/4.0 with 420EX on-camera, with omnibounce. Colour space in PS - sRGB. RAW capture processed in C1.


http://pbase.com/image/26196371.jpg

Thanks for your comments and suggestions.

regards,
Ian

[drisley]

Sometimes there is a colour shift when saving to web format.
You would think converting to sRGB first would prevent this, but I've seen otherwise.
One Photoshop trick I use to make sure I can see what the output image looks like, is to select View>Proof Setup> and select Monitor RGB (which enables proof colours).
Of course, your monitor has to be be colour calibrated, as well as Photoshop.
This seems to give a good idea what the image will look like when output to web.

I know that when I do gif graphics for websites, there is often a HUGE difference in colour.

[igas]

Thanks Drisley for your explanation.

I am a bit wiser now :roll: You were perfectly right about the proofing, the colours match pbase exactly when I select Monitor RGB as the proof setup.....but.....still don't understand why I have to tell Photoshop about this when it should already know. There is no change when I switch between RGB and WindowsRGB, which should be there to approximately match the vast majority of (uncalibrated?) pc monitors out there.

My monitor is calibrated and profiled (ColorVision) and so is my printer (Kathy Stratton). Like...if the PS sRGB colour space does not match the web or the print profile, what is it there for? I must say I am slightly confused.

Regards,
Ian

[/b]

[Avarond]

The target profile is there in case you are going to a different medium. In prepress you use one of the CMYK sheetfed, webfed profiles, etc. Or if you are strictly going to an inkjet printer pick the profile that matches the output on your printer. Gets kind of confusing but once you plug in the right profiles in the right place it works like a charm.

[igas]

Hi Larry,

Yes, you are right, there are certain cases when photoshop cannot be expected to show you by default what your final output will look like, so you switch to that proof setup before you start playing with your colours.

I just thought that there would be at least one instance when plain sRGB or adobeRGB would give the correct results; without having to remember to go to view>proof setup>etc before. Or maybe I still haven't grasped the concept. :(

regards,
Ian

[drisley]

Igas,

I am with you on the confusion!

I only recently discovered this problem when I was designing a new website. The main colours of the website were monotone "purplish".
I had the document colours set to sRGB and my monitor calibrated.
BUT! When I saved the images, in gif and jpeg format, for web output, suddently the colours shifted dramatically to more of a "pinkish" hue.

After MUCH frustration trying different colour management settings, I came across this "monitor proofing" setting. It is still VERY frustrating, and I haven't come across any more info on the subject (very surprising actually). So, now when I work on images destined for the web, I always enable the "monitor proofing".

Really, I thought the sRGB format took care of all this, but perhaps it's geared mainly for printed output, not web output.


I also found this link which states:

"Before explaining how to configure Proof Setup I hope you also notice the three RGB options towards the middle of the drop-down menu. You can actually use these to preview how your image will look on other platforms, e.g. Mac or PC and on your own computer outside of Photoshop using the Monitor RGB option. . The Monitor RGB option is effectively the same as switching OFF the "Display Using Monitor Compensation" checkbox in Photoshop 5. Assuming that you are NOT using a VERY wide working space e.g. EktaSpace or Adobes Wide Gamut RGB the Monitor RGB option also provides an effective method of checking the quality of your monitor profile. If on selecting Monitor RGB, the image turns very ugly you can take it as read that the monitor profile is messed up. By ugly I mean significantly different, large colour shifts. Not just a bit brighter, darker or flatter (e.g. whites turn yellow)."

[igas]

Drisley,

Yes, I think that is what I will do - enable monitor proofing when preparing images for the web. Although I am with you here that it does not seem to make sense.

But now that I think about it, and as I said in my other post; the fact that our monitor is calibrated, and that when switching between sRGB and Windows RGB colours stay the same (at least with my set-up)....hopefully people with calibrated monitors who see our images, should see what we see with our monitor proofing enabled. Right!? (Too bad for those whose monitor is uncalibrated; although I hate to say so).

As for printing, the whole proofing thing makes sense, as photoshop would have to find a way to show its master (that's you and me) what his print would approximately look like. It's success in this matter is open to discussion. But as I print through qimage, this becomes a moot point.

Off to bed now. Check back tomorrow.

g'night
Ian

ps: just read the last paragraph of your post; very interesting. Just a few more posts and we should have this cat skinned :wink:

[maderito]

Thanks Drisley for your explanation.
My monitor is calibrated and profiled (ColorVision) and so is my printer (Kathy Stratton). Like...if the PS sRGB colour space does not match the web or the print profile, what is it there for? I must say I am slightly confused.
[/b]
When in Photoshop, you are viewing your image in the sRGB or Adobe RGB color space. The color numbers of the image are adjusted "on the fly" to recreate the sRGB color using your monitor (which may not be sRGB).

Thus working with RGB numbers and using ICC profiles
10,0,0 image color (say in sRGB color space) =
5,1,1, color in an independent reference color space =
6,2,2 color in your monitor's color table

These conversion are accomplished by connecting the input ICC profile (sRGB) to the output profile (your monitor ICC profile).

What you see in PS is 6,2,2 - your monitor's equivalent of the 10,0,0 sRGB color.

Outside of Photoshop, 10,0,0 would be sent directly to your monitor and would reflect your monitor's 10,0,0 value which would be different than sRGB 10,0,0.

When you select Monitor RGB in the proof view, you're sending your image data directly to the monitor lookup table without the mediating influence of Photoshop's color management. In other words, you are disabling PS color management.

When you view your image with Monitor RGB proofing, you are seeing exactly what would be viewed outside of PS and what you would see if your image were displayed ON YOUR MONITOR by any web browser that did not change color numbers. Go next door, and it may look different on your neighbors monitor. :)

A well calibrated monitor on average has a color space that approximates sRGB which is why working with sRGB in Adobe will approximate (but not equal) the view seen by most monitors.

Perhaps helpful?

[igas]

When in Photoshop, you are viewing your image in the sRGB or Adobe RGB color space. The color numbers of the image are adjusted "on the fly" to recreate the sRGB color using your monitor (which may not be sRGB).


A well calibrated monitor on average has a color space that approximates sRGB which is why working with sRGB in Adobe will approximate (but not equal) the view seen by most monitors.

Perhaps helpful?

Yes Woody, very helpful...and thanks for joining in.

One question (before i fall asleep on the k'board):
In your opinion, should the real-life colours match sRGB working space in Photoshop or the monitor proof? (assuming we could get them to match either one or the other!)
The print is something else.

Ian

[maderito]

[quote=maderito]
In your opinion, should the real-life colours match sRGB working space in Photoshop or the monitor proof? (assuming we could get them to match either one or the other!)
Ian

Hmm...Interesting question. I think many monitors in common use that are not worn out have gamuts that exceed sRGB. If your monitor is in this category, your images might look better when proofed against your monitor color space. The problem is that you wouldn't be able to reliably share your satisfaction and joy with others. Your monitor profile doesn't travel with your images when uploaded to other computers.

I routinely use Adobe RGB for all images, whether viewed in Photoshop or on my computer via a web browser. I only convert them to sRGB when sending them for viewing elsewhere on the web. My monitor (Sony Triniton) seems to be reasonably good in displaying the Adobe RGB color space. But I haven't evaluated this rigorously.