Question about monitor calibration and photoshop

[trakakis]

<p>Hi!<br>

I would like your help if this is possible.<br>

Until now, I had my monitor uncalibrated. I used to work on sRGB with my camera, and on sRGB on Photoshop CS4 and I still work with this color space.<br>

Before some days, I calibrated my monitor using Pantone Huey Pro. The problem is that after calibration, when I open a photo in Photoshop I see different colors. This happens only in Photoshop and Photoshop Elements. For example in Corel Paintshop I see the correct colors. I also have to notice that when I edit a photo on Photoshop and then save it and open it with a different program the colors are ok. Only during editing I see strange colors. I also printed photos at a proffesional photo store and colors were ok.<br>

Has anyone an idea why I see strange colors during editing? For example, blue color look like violet. I guess in Photoshop color settings I have to use sRGB color space, not monitor's new profile from calibration, right?<br>

I would appreciate your help!<br>

Thank you.<br>

George</p>

[see_r]

<p>In general I have noticed that in Photoshop blue appears a bit violet. This observation has nothing to do with the quality of monitor calibration, and appears to be a shortcoming of Photoshop. It is consistantly reported on the web and observed across monitors. Most importantly, I became acutely aware of it after starting to oil paint when the RGB value 0,0,255 (which should be blue) looks very much like French Ultramarine, which tends toward violet.<br>

One thing you coud try would be to make sure you have your Color Settings to North America Prepress 2 and when you open the file convert to Adobe RGB to see if you get improvement there, but I don't. Either way you should set to Prepress, not the default General setting so that you always are alerted as to any color profile mismatching or lack of embedded profile. You can read more about all of this in the series here on PN on Color Management, which is really quite good.</p>

[trakakis]

<p>Firstly, I really appreciate your help! Very kind you answered to me!<br>

I open photoshop and create a blue page (0,0,255, sRGB color space). Well, it behaves like violet. Then I save it, I open with a different program (for example Corel Paintshop or Microsoft Picture Manager) and I have a nice, true, blue color! So I think you are right.<br>

But my Color settings at Photoshop are ok, aren't they? I mean I should use sRGB, or AdobeRGB, not monitor's profile, right?<br>

Of course I am going to study PN's series on Color Management!</p>

 

[see_r]

<p>It's hard to know about your color settings without looking at your computer, especially when were talking about color management via Photoshop, which is not very intuitive and which has several places to deal with color management. Another thing is that color management is not all science, it's part art. So a "correct" set of color settings can not exist on any system unless they are correct for you under a given set of circumstances. For example, the nice series here on PN on Color Management will discuss previewing your images using your printer profile and will suggest some ideas (and limitations) towards interpretation. But ultimately, there are faults and the best thing I can suggest is to do a lot of experimentation so that you develop an excellent understanding of the relationship between what you see on your computer screen and what prints out--all under a given set of ambient light circumstances. I spend many hours dealing with all of this last winter. Ultimately, the print and the screen can never look exactly the same all of the time. A lot of this has to do with differences in ambient light, perception, shortcomings in the algorithms, and differences in the materials of the print vs. the screen.<br>

And actually, I don't think that color management series placed enough emphasis on the idea that the way an image appears is entirely dependent on incident light. The other night I took an alarm clock that has a blue LED, walked all over the house and shined it on all of my photographic prints and paintings. It was a real trip; everything looked totally different. Anyway, when color managing prints, it's important to keep in mind the light of the final home of the print may change, eg from incandescent or fluorescent light to daylight-totally different. Photographers are often working with settings that assume a clear sunny day under ordinary atmospheric conditions.<br>

Finally, a word on perception. In the article series, all you have to do is just go to that figure that shows the difference between looking at a lowly saturated orange box in a highly saturated orange box vs that same dull orange box in a blue box. Same color, same incident light--looks totally different. The dull orange box looks a lot brighter when surrounded by blue than when surrounded by bright orange. Color management, your print your computer and your screen have nothing to do with this--that happens entirely in the brain. So in comprehensive "color management" you have to deal with perception, and therefore, art.</p>

<p> </p>

[see_r]

<p>Oh, yes, you should probably just set to Adobe RGB</p>

[trakakis]

<p>Dear Chip<br>

Thanks for your response and for your detailed answer. You are very kind!<br>

I think I'm going to study in detail PN series for color management this weekend!<br>

I would like to ask you something more, if you can spend a little more time; is it possible that the problem is generated from a bad profile from Huey? Is it possible that Huey doesn't work properly? How can I examine if it works ok? Maybe trying on a different PC?<br>

Thanks for your help!!<br>

Best regards,<br>

George</p>

[see_r]

<p>I don't know much about Huey. I use the Colormunki, and like it. It also comes highly recommended for it's price point. But based on your descriptions what you are observing is Photoshop vs. other image editing software. Basically, Photoshop is higher maintenance. Enjoy!</p>

[joe_c5]

<p>There are two possibilities.</p>

<ol>

<li>The monitor calibration and profile are correct and the “strange colors” in Photoshop are as close as your monitor can get to the real colors. The colors in any software that does not support color management will be wrong. This is the more likely of the two. </li>

<li>The monitor calibration and/or profile are not correct, and none of the colors are the real colors, whether in Photoshop or Paintshop. This is less likely, but not impossible.</li>

</ol>

<p>Unfortunately I do not have any good suggestions for figuring out if your monitor profile is correct or not.<br>

You should use a standard color space as Photoshop's working space. sRGB is a good choice unless you need something else specific. I do not recommend using the monitor's profile as a color space.</p>

[tomadakis]

<p>George, if I were you I would also post this question in the "Digital Darkroom" forum.</p>

[Tim_Lookingbill]

<blockquote>

<p>Has anyone an idea why I see strange colors during editing? For example, blue color look like violet.</p>

</blockquote>

<p>I don't know how violet your 255 sRGB blue purity previews in Photoshop, but in a color managed environment the blue you see in a non color managed environment like in a web browser is not a defined color where as in Photoshop and other CM apps it <strong>IS</strong> according to the color gamut shape described in the custom display profile and translated by way of Lab color space.</p>

<p>If by strange you mean way off oversaturated almost dayglow color, then you may have a corrupt profile and you need to recalibrate. We don't know what you mean by strange but below is a demo of how 255 blue appears on my well calibrated iMac color managed and not color managed.</p><div></div>

[Tim_Lookingbill]

<p>Everything about color management is about mapping color to different gamuts where precision may not be at optimum especially when mapping purities like 255 blue which are close to exceeding the gamut of the display. The description of how 255 blue purity should look is subject to the luminance and color temperature levels for each display which can be different between displays where as synthetic color spaces like sRGB, AdobeRGB and ProPhotoRGB have fixed and defined luminance, gamma and color temp describers making up their gamut shape.</p>

<p>Below shows how the previews can change on the max display gamut two 255 blue purities posted above according to the space SHAPE they're converted to. The top shows two distinct blues retained by converting to ProPhotoRGB and clip by looking the same when converted to AdobeRGB, a much smaller space with a much different color gamut shape.</p><div></div>

[trakakis]

<p>Dear friends,<br>

thank you all for your interesting responses! You are all very kind!!<br>

Here is what I mean with strange blue color (0,0,255);<br>

<img src="http://img38.imageshack.us/img38/5461/image3qj.jpg" alt="" /></p>

<p>I think you can see now the difference!<br>

I'll give you other one clue [ :-) ] ! I calibrated the monitor I have on my work (it's a CRT) and Photoshop displays blue color ok, exactly like Paintshop. I have no problem there!<br>

So, this means that calibrator is ok, and my monitor can't support blue color after calibrating (true blue color is out of display gamut), am I right?<br>

So I need a new monitor (anyway I am thinking for a long time to buy a new one!), don't I?? Or something else is happening?<br>

Thank you very much, and sorry for my bad English!! :-)<br>

Best regards to all of you,<br>

George</p>

[Tim_Lookingbill]

<p>George, you're 255 blue purity is as it should look in a color managed environment. You converted your screenshot to sRGB which now exaggerates the differences when I view it in color managed Safari. I assigned my iMac profile and got the same blues I get in my screenshot.</p>

<p>All I can say is this is the price everyone pays including myself as demonstrated above for implementing a color managed workflow. It's kind of like the "Lord of the Rings" movie where the line goes "<em>One ring rules them all" </em>in this case Lab space, ICC standards and a wide range of software and hardware vendors are all onboard calling the shots deciding what color should look like on a computer according to Lab space. There may be errors, imprecision and fudging along the way. THOSE DIGITAL COLOR DUDES AREN'T GOD!</p>

<blockquote>

<p>I calibrated the monitor I have on my work (it's a CRT) and Photoshop displays blue color ok, exactly like Paintshop. I have no problem there!<br />So, this means that calibrator is ok, and my monitor can't support blue color after calibrating (true blue color is out of display gamut), am I right?</p>

</blockquote>

<p>Again this seems to point to a gamut mapping issue along with the limitations of using a simplistic and cheap RGB filter driven colorimeter. My i1Display produces the same 255 blues. I'm not complaining and I've been using this technology since 1998.</p>

<p>There could be a number of causes as to why these blues look as they do. Your CRT probably has an sRGB color gamut that mates well with the filters used in the colormeter while your LCD has a much wider gamut that may challenge the RGB filters of the Huey which may induce color transform errors within the custom profile in how Photoshop and Paintshop reproduces these blues mathematically referencing the display profile. Again this may be a limitation (imprecision) of the technology we have to live with.</p>

<p>Try this...</p>

<p>Assign in Photoshop one after another a number of color spaces to your screenshot and see how they change. It's either a gamut mapping error or how each color managed app deals with the display profile as written. One things for sure no one's fixing this so it doesn't seem to be an issue for most folks.</p>

<p>You may not like the colors you get in a color managed environment but it's still by far the most efficient way to edit and reproduce faithfully those color edits across a multitude of devices as <strong>technology and physics will allow</strong>.</p>

<p>You are shooting and processing photographs, not flat blue swatches of color that can't be reproduced faithfully on any printer anyway.</p>

<p>If you want to reproduce the non color managed 255 blue purity on your display I'ld suggest you work in a wide gamut color space like ProPhotoRGB. I've tried to reproduce that blue in AdobeRGB using Photoshop's Color Picker and couldn't get it but I could in ProPhotoRGB or my display profile space which BTW should NOT be used to edit in.</p>

[Tim_Lookingbill]

<p>Read up on Lab space and Euclidean Distance mathematics within gamut mapping which expects one color to map in a straight line to another. Physics doesn't always work that way and it has been proven that Lab isn't as uniform as we'ld like to believe according to color scientists and mathematicians.</p>

<p>http://en.wikipedia.org/wiki/Lab_color_space</p>

<p>And this one:</p>

<p>http://en.wikipedia.org/wiki/Color_difference</p>

<p>scroll to the Tolerance section showing the Locus shape graph and examine the <a title="Ellipsoid" href="http://en.wikipedia.org/wiki/Ellipsoid">ellipsoidal</a> shape squeezing that happens in the blue regions.</p>

[Tim_Lookingbill]

<p>Here's another one about "Blue Turns Purple" from a color scientist:</p>

<p>http://www.brucelindbloom.com/index.html?MunsellCalcHelp.html#BluePurple</p>

<p>Bruce states:</p>

<p><em>"Unfortunately, the Lab color system is not perfect in its ability to match its hue angle with perceptual hue."</em></p>

[trakakis]

<p>Dear Tim,<br>

all your posts are so useful!! I'm going to study them in detail, but I think I have already understand many things.<br>

I examined that if I use ProPhotoRGB in Photoshop and create a blue layer (0,0,255) it looks perfect!<br>

Here is one thought; when I open an sRGB photo, I work with it in Photoshop in ProPhotoRGB. In this color space I found out that if I decrease the Hue of Blues, I take a better blue, not purple or violet. Then I convert to sRGB and save the photo. Is this correct?<br>

(I have spent a lot of your time, so if you don't answer that's ok!! I appreciate your help!!!)</p>

[trakakis]

<p>Well, I found that the (0,0,255) in Photoshop is actually looks exactly like (87,1,255).<br>

A possible explanation can be found <a href="http://www.imaging-resource.com/ACCS/HUEY/HUEY.HTM">here</a>;<br>

"<em>If you do this for a living and print on art stock or use custom inks, investigate the ColorVision solution. In our experience, the Spyder2 Pro has produced the most consistent and accurate screen adjustments of any solution we've tried. Our Spyder created a profile with a slightly larger gamut (more blues) than our huey profile.</em>"<br>

So I think that Huey creates a profile that has limited gamut at blues. I tried in other two monitors (almost new ones) and I saw same results. (0,0,255) is like (87,1,255).<br>

So now I'm wondering if the Spyder would create a profile with larger gamut that would display blue color in Photoshop more accurate and if it worths giving money to buy one...</p>

[Tim_Lookingbill]

<p>Check out this 2007 blue turns purple on a MacBook laptop thread I participating in.</p>

<p>http://www.photo.net/digital-darkroom-forum/00KIfk</p>

<p>Scroll down to my first post where I provided a screenshot showing what a transform error within the matrix of an eyeball calibration profile does to blues and reds even on a ten year old Mac OS 9 system. I sampled the blue on the right in that screenshot off a CRT I had back then on my more current OS X iMac and get 61,0,251 RGB on the Digital Color Meter but it reads 0,0,255 in Photoshop.</p>

<p>I assign my iMac profile and it now looks like the 255 blue purity I get creating it in ProPhotoRGB or in my display profile space. The thing is without this comparison assigning my iMac profile I would've never known the difference.</p>

<p>You can try and see if the Spyder system will fix this blue to purple RGB purity issue, but something tells me there's way too much going on under the hood mathematically to know for sure.</p>

<p>It's only about $80 extra to find out.</p>

[Tim_Lookingbill]

<p>Just stumbled upon an odd color shift anomaly with this 255 monitor blue purity experimenting with conversions you might give a try. It may explain a bit about what's going on here.</p>

<p>Create a New document in Photoshop and convert to your custom display profile. Go into Color Picker and enter 0,0,255 blue to create a box shaped fill in the new doc using the marque tool.</p>

<p>Afterwards convert to ProPhotoRGB and create the same marque box selection making sure a portion overlaps the previous fill and go back into color picker to make sure you have 0,0,255 RGB blue, enter the numbers if necessary. Create a new fill with the overlapping marque box.</p>

<p>Now convert to Lab Color and see if the ProPhotoRGB blue purity fill changes color. On my iMac system it changes to a dark sort of navy blue but the first color fill created in the display profile space stays the same.</p>

<p>Fun with math! This has got to be a mapping error. Otherwise I'm stumped.</p>

[trakakis]

<p>Tim, you are the scientist of color!!!<br>

To be honest, I don't know exactly what means "Assign Profile"; It just changes color space? Isn't it the same with the "Convert to profile"??<br>

Sorry for bothering you, I just try to understand some things and <em>how I can work in Photoshop</em> (what procedure to follow) to have as "true" colors as I can.<br>

If I use sRGB in Photoshop and create a (0,0,255) layer, it looks as I mentioned like (87,1,255). When I Assign Profile to ProPhoto RGB I take the true (0,0,255). This means that I should follow everytime this procedure to work with and then at the end converting to sRGB?</p>

[trakakis]

<p>Oops!! I did't see your last message!! I'll try immediately!!</p>

[see_r]

<p>Hi Gerorge,<br>

Regarding your questions about assigning a profile or converting from one to another: without a color profile, the RGB value is a computer file which essentially is nothing but a set of binary values, one for each chanel, with a range of 2 to the 8th power (256: from 0 to 255, inclusive) for 8 bit (bit means 'binary digit' so 8 bit = 2 to the 8th power =256 possible values. or 2 to the 16 for 16 bit, etc. Your devices (printers, monitors) need a means of translating the data from the image file towards output (or in the case of a scanner, translate from the device to the computer file). A profile, therefore, contains the algorith that relates the computer file data (whether RGB, CMYK, etc.) to or from the relevant parameters required to drive the device, and therefore to translate the bit value to the actual actuated output for your devices, or actuated input from a sensor of a digital camera or scanner to a computer file. <br>

So to your question: "assign profile" actually means that you have no profile specifically connected with the file (and so some default profile is used [or else nothing would be able to display), and "convert profile" means that the color space of the profile is not the same as the color space assigned to the working space of the program you are using (in this case Photoshop). In either case, a conversion still occurs (there is obviously some default profile connected with the software drivers, etc) without you assigning a profile or converting from one to another, and frequently does not create a problem so long as the color spaces are within the same bit depth, eg. from 8 bit to 8 bit such as occurs if you go from sRGB to Adobe RGB. But when you go from 8 bit to 16 bit, such as when you go from sRGB to ProPhoto, then you can often run into problems with conversions. I haven't dug in enough to understand what the mathmatical error is...I'm no color scientist. I just know this empirically.</p>

[trakakis]

<p>Tim,<br /> I did what you said (I hope right!!) and it happened exactly what you said!! After converting to Lab ProPhotoRGB blue purity fill changed color, while first fill stayed the same!!!<br /> Here you can see;<br /> Before converting to Lab<br /> <img src="http://img203.imageshack.us/img203/7413/85468232.jpg" alt="" /></p>

<p>After converting to Lab<br /> <img src="http://img31.imageshack.us/img31/3597/36366983.jpg" alt="" /></p>

<p>So this means that we have a mapping error?!? What exactly is this? Can I fix it some how? Does the monitor or the calibrator not work properly so I could buy another to fix the problem? You are fantastic!!!</p>

<p>Chip, very helpful your post!!! I think I understand now!! Thanks!!!</p>

[joe_c5]

<p>I probably should have spoken up sooner, but if the color management is adding red to a pure blue tone, it is because the monitor's gamut is too small to show the real blue color.</p>

<p>The closest it can get is to add a bit of red, hoping that slightly magenta is closer to the real color than the monitor’s greenish blue was.</p>

<p>You do not want to do strange things to the colors to force them back to your monitor's blue color, since this will only ruin the color for anybody else with a wider gamut monitor.</p>

[Tim_Lookingbill]

<p>George, go a step further and go back into the color picker while still in the Lab space and set your 255 blue purity there as before and create a fill. Lab's version of that color will appear with more magenta than the others.</p>

<p>Now what you're trying to determine is whether all of this color shifting is normal or if it's an error. Out of over 16 million possible colors available on your display, I don't think you can determine this or determine if it's a real issue at all with just one color in a color managed environment.</p>

<p>I don't think it's that important to know as long as your photos look as you intend. You can always get the blue you like in ProPhotoRGB.</p>

<p>I came across a more thorough "Blue To Purple" explanation at the same Bruce Lindbloom site that tells a bit more where he comes up with Uniform Perceptual Lab space of his own to try to address this:</p>

<p>http://www.brucelindbloom.com/index.html?UPLab.html</p>