I blew it in the previous post when I said Qimage doesn’t do color management. I’m not sure what I was thinking; I had forgotten that I had used the color management features in the previous generation of Qimage, and I couldn’t find them in the v2011.136 version that I am currently using. The reason I couldn’t find them was a program configuration issue. In the “job properties” screen at the lower right- corner of the Qimage main window, there are two pull-down menus for ICC profiles. The top one allows you to select the monitor profile, and defaults to the current operating-system-selected monitor profile. The second one allows you to pick the printer profile. However, in the default configuration of Qimage, a message is displayed to the effect that you should do color management in the printer driver, and it doesn’t show you any of your computer-stored ICC printer profiles. To change this, and allow Qimage to do color management, you need execute the following menu sequence: the Edit>Preferences>Color management (ICC). Once you do that, you check the box allowing Qimage to do the color management, and pick the printer profile you want from the drop-down list. There’s one little wrinkle: it looks like the access button for the drop-down list is grayed out; if you click on it anyway, the list appears.
I evaluate color management using a suite of TIFF images that I got from Charles Cramer. When I loaded the first one into Qimage, the colors were completely wrong on the monitor. All of the Cramer calibration images use CIE 1976 (L*, a*, b*) D50 as their color space. It looks to me like Qimage won’t handle Lab color, although it doesn’t complain when presented with a Lab image. Just to make sure, I printed the image using a profile I had created in Eye-One Publisher; it printed with the same wonky colors that I saw on the monitor. Converting the TIFF file to PSD in the Photoshop CS5.1 and reading the file back into Qimage produced colors that were in the same ballpark as the right colors, but they were pretty far off.
I don’t use Lab color in my current work, but in the past I have used it extensively. It wasn’t a great choice when Photoshop only supported eight bits per color plane. Because the Photoshop implementation did not provide for image-dependent scaling, they needed to pick minima and maxima for the chromaticity axes that made color space huge. That had the unpleasant side effect of causing posterization when quantized into 256 levels and then manipulated. Going to 16 bits per color plane eliminated that problem. I used Lab quite a bit for a while, and I still occasionally need to print those images. To do that using Qimage, one workflow would be: first sharpen the L* channel, then convert to printer color space, then let Qimage do the resampling. Another would be: convert to printer color space, and that to image resample and then sharpen. Neither is optimal for Lab image; sharpening should be performed after resampling, and it should usually be performed only on the L* channel.
I converted the calibration images to ProPhoto RGB using absolute colorimetric as the rendering intent. I printed them from both Photoshop (using ACE) and Qimage with perceptual rendering intent, and compared the results. They are visually identical, but not quite the same as the Lab image printed directly from Photoshop, showing that the fewer color conversions, the better.
So, I stand corrected. If you don’t use Lab color, Qimage does indeed do color management, and does it as well as the Adobe Color Engine. The last bullet in the preceeding Post should read:
- Export the image from Lightroom. Open Qimage, configure the printer driver, pick the resampling algorithm, and let Qimage send the file to the printer. Don’t forget to go back and delete the exported file.