Mike Chaney's Tech Corner

Hi, Mike.

I recently noted a problem in printing grayscale image files. The files in question were PSD files, grayscale colour mode, "Dot Gain 20%" profile embedded (I usually keep my Creative Suite sync at North American Prepress 2). The prints were coming out much darker than on screen in Photoshop. After recalibrating my monitor (I use a ColorMunki Photo), same result. I doubled checked both Photoshop and Qimage were using the correct monitor profile (they were).

Then I noticed that the preview in Qimage (Studio Edition 2009 v268) was also much darker than in Photoshop. The prints were matching Qimage, but Qimage wasn't matching Photoshop.

The other thing I noticed...with the grayscale images, I was getting a "Gamma not 1.0" error. I did several forces setting resets to try to clear this, but Qimage would always give me this error with the grayscale images.

To resolve the problem, I converted the images to RGB colour mode with Adobe RGB profile and all was well. Qimage preview matched Photoshop and so did the prints.

AFAIK, this could be the first time I've actually tried to print a grayscale image file with Qimage. What am I doing wrong?

Thanks.

Brad Grigor
Turning Point Arts

Brad
In order to use colour management which QImage relies on to get the correct colour (including B/W) the image MUST be in RGB mode - greyscale files will not work. To me, this is the best way to print black and white without using specialist inksets.

Brian

As far as I know Qimage will convert a greyscale image to RGB on the fly and will respect an embedded "profile" like Gamma 2.2 but possibly not the Dotgain etc descriptions which in my opinion no B&W photographer should use in an inkjet workflow. Not that I use either. Normally I convert the greyscale image in Photoshop (P2P) from Gamma 2.2 to a custom QTR B&W profile and feed the greyscale image to Qimage with its CM off.

addition: PSD files and on top of that layers included isn't the best choice for feeding Qimage. Stay with Tiff's and JPEG.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

My conversion is Image>Adjustment> either Channel Mixer or Black-and-White using a green, yellow, orange, etc. filter as I would have done on B&W film.  Depends on the scene.  Once I get basic Curves, Levels, etc. done I save as xxxxBW--TIF, PSD or JPG--depending on ultimate size.

I haven't had trouble with QISE dealing with layered files; just takes longer to queue to the printer.  Once I know it is going to work without further adjustment I may go back in and flatten the layers.

When I dump to the printer I turn off profiles in QI since I use the ABW on Epson.   For some reason (but not always) there is a difference between No CM and Let printer driver handle color in QI.  It's almost like double profiling.  I have trained myself to just turn it Off all the time. 

Hi Seth,
This is in fact the case. If you go to the CM dialogue and press F1, the full details are there. Briefly: No CM means what it says and Let printer driver manage color uses a generic profile (pRGB). But, you set the driver differently to ICM and "Applied by Printer Software" if available.
In the Help where CM "OFF" is mentioned (printer profile un-checked), it says use when "if you want to send raw data to the driver."
Terry

With "let printer handle color" the attached profile passes to the CM of the printer driver. If there wasn't an attached profile to the file the  result will be like "No CM".  With "No CM" only the image data goes to printer driver.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

Hello everyone and thanks so much for the quick replies. Just to clarify, the original image had already been converted to B&W but it was in an RGB colour mode. The only reason I changed the colour mode to Grayscale was to reduce the file size. I had never done that in the past and I have printed a lot of B&W through QImage in RGB colour mode with exceptional results. NOTE: I use the Prepress color settings because I do a lot of press work, and Dot Gain 20% is a reasonable default when preparing grayscale images for halftone printing on uncoated papers. It didn't make any visible change on screen in Photoshop, whereas the other profiles, e.g. Gamma 2.2, will. So I was a bit taken aback when the print density was so far off. However, this is no big deal for me--I will just stick to my original tried-and-true workflow.

Cheers!

Brad