Good dispcalGUI calibration yet gray 'blacks'

[demianov]

<p>Hello.<br>

A couple of months ago I discovered the dispcalGUI. Thanks to a few very helpful gentlemen on this very forum I was able to obtain an almost excellent calibration of my Dell U2711 panel. If you're reading this, I must say again than I'm truly grateful.<br>

For anyone else who's interested, you can find that post but it's long and it's boring and you don't need to get into it.<br>

I am most happy with the marvelous job that dispcalGUI was able to do except for one thing. The blacks aren't really black and this is interesting because I think that the problem has to do with the colorspace mapping and not the actual calibration of the panel. I will describe the problem in detail.<br>

Let's take Photoshop, for instance. The color of the area that surrounds the image can be changed. A right click gives you the choice of: Gray, Black or Custom. Let's assume that my choice is "Black". I open a file and start working on it, trying to get the shadows look really deep but no matter what I do, the pure black of the image does not approach the "Black" border that surrounds the image. Even when I create a new document and fill it with "black" it still looks brighter than the black point of my panel. I'm attaching a screenshot so you'll get an idea of what I'm talking about. The color sampler said that my RGB values were 0,0,0. When I grabbed the screenshot and pasted it into a new document, the color sampler gave me a reading of RGB 8,8,8 in the same area. I'd think that the black point in photoshop was messed up or something but this happens EVERYWHERE. In Lightroom: same deal! I make the background black but cannot approach those levels in my photos. ACDSee 12? Exactly the same! Even in GOM player! The black point is set to be brighter or something but in which colorspace? My panel's? This seems to happen in every color-managed piece of software, regardless of the actual colorspace. In my 'Photoshop' example the case is exactly the same even if the colorspace is sRGB, for instance.<br>

I just probably messed something up so I'll describe the kind of calibration I did. I must say though that the native software my Spyder3 Elite came with did no give me this kind of issue. However, in every other aspect, the calibration it did was detestable, to say the least.<br>

Using my panel's controls alone I am able to approach my target. With NO calibration at all the panel is at ~6450K, 71 cd/m2 and gamma of 2.1 (I don't have the black point value right now)<br>

The target is: 6500K, 70cd/m2, gamma 2.2, black level: native. There are two check-boxes, one next to "White level" and one next to "Black level". They both read: "Drift compensation during measurements". I don't know what that means but they're both checked. Calibration quality and Profile quality are set to "High". The most important thing here is the Profile type, which is: XYZ LUT + matrix. I tried a "Curves" type profile but that gave me unacceptable results. So for my LUT type of profile calibration I created a custom testchart with 886 patches. I really had to have there 256 gradations of neutral density. I don't think that the test chart has anything to do with my problem though. Next to the 'Profile type' drop-down menu there's the "Advanced" button. I did figure out what Gamut mapping means, however, I couldn't for the life of me understand what I should have in the "Source profile". I didn't change the default which is still: C:\Program Files (x86)\dispcalGUI\ref\sRGB.icm Everything below it is grayed-out because all of the options for gamut mapping are unchecked.<br>

What did I do wrong and what should I do to get me true blacks that match my panel's black point? Should I set the Source profile to: Adobe RGB? Another reason tells me that the sRGB as the source profile isn't right is that both in Photoshop and Lightroom some of the blue tones started looking weird and I know that sRGB doesn't like those tones. But then... Since all of my Gamut mapping options are unchecked is the 'Source profile' selection even relevant here?<br>

I must add that my display is a wide-gamut panel. From previous measurements I know that it is able to produce certain tones that stray quite far outside even the 'Adobe RGB' colorspace. My display adapter has a 10-bit LUT, with dispcalGUI being able to make use of those extra bits thanks to the DisplayPort connection.<br>

The OS is Win7 64-bit Pro, so maybe there's something inside the system itself that makes my life hard. I don't want to detail my color management settings at the moment but I'll say that I did configure them and I'm pretty sure they're correct.<br>

I really don't want to start troubleshooting because apart from the black levels, the calibration is really good and I don't want to mess with it but if anyone sees an obvious problem with my settings, I definitely need to hear about it. I guess, I just need to know that if I'm doing something - I'm doing it right.<br>

Thanks!</p><div></div>

[blumesan]

<p>Suggest you post your question in <a href="http://sourceforge.net/projects/dispcalgui/forums/forum/932493">this forum</a>. The program author is very kind and helpful.</p>

[demianov]

<p>You're right. Thanks.</p>