Mike Chaney's Tech Corner

hi All,

I have tried to remove a magenta cast with the printer filter, setting Red -2 or -10 in white balance.

However, I cannot see any difference.

What could I have done wrong?!

ciao,
-Gian

Hi Gian,
Reducing Red in White balance will make the image "cooler" towards blue but not really affect magenta.
You'd be better using the saturation feature, un-tick the lock, select magenta and apply a negative value: 0 to -100 is available.
Alternatively, you could use the Select Color feature (SEL COL tab) but that requires a bit of practice to use!
How about getting back to first principles and Colour Management. Is your monitor calibrated, are you using a printer profile for the printer, paper and ink combination you are using?
If you do not have a printer profile, use Qimage set to "Let Driver manage Color". Read the help under Color management for advice on driver settings.
Terry

Follow up
The amounts you mention for adjusting in White Balance are very small.
See attached image below that was way out on WB, notice that it required +52 red and -29 Blue to correct it in the editor - quite large numbers!
Terry

Terry,

thanks for your kind reply.

I do not know much about color management, so I have a lot to learn.

In fact, I was experimenting, and was surprised to see no effect.

I will try your advice, and do some homework.

Anyway, I had my monitor hardware calibrated, and I am using the correct profile for my Epson printer and paper.

-Gian

So to understand your problem correctly, do your images look right on your monitor and only the prints have a magenta cast - or do the images look bad on screen too?

If it's only the prints that have the magenta cast and you are using a monitor and printer profile, I suggest you look for the source of the problem and not try to correct it with a print filter.
There are some possibilities:
1. The printer driver is not set correctly - it should be ICM and "no color adjustment". Tell us what printer you have and the settings being used. Attach some screen shots.
2. Qimage is not set correctly: is the printer profile set and enabled, again, attach a screen shot?
3. This may sound silly but is a common problem - do a nozzle check and make sure the test pattern is complete - a blocked nozzle will affect the colours.
4. Are you using genuine Epson inks: an Epson profile probably will not work with so called "compatible" inks?

Terry

Terry,

I am testing right now.

I prepared three filters, with Magenta -20, -40 and -60.

I printed a stormy sky that shows no magenta on screen.
There is no difference between unfiltered and M-60.

The settings for my R800 are Icm, NoColorAdj, monitor profile, Epson PremGlsyBstPhoto.
Only original inks, recently cleaned nozzles, no striping or other visible defects.

Considering that the monitor is profiled, my goal is to print accordingly.

One question, though.
The image I'm printing is Adobe RGB 1998.
Could that matter?

thanks for your help,
-Gian

Have you saved the filter with a unique name? On your screen shot, the Print Filter box is not ticked. When that is done you will be prompted to select a filter file.

That's good, I have an R800 too and get superb prints that match my monitor extremely well and there's no reason why you should not get the same.
BUT .. have you printed a nozzle check pattern just before you print - look at it carefully, clean until the pattern is perfect, no breaks.
Sorry to go on about it, but I cannot see any other reason for getting a magenta cast on your prints.

No, it should not. Qimage is fully colour management aware. There is a possibility that the image is not tagged in its exif data or the Adobe profile is not embedded.
You can check by hovering you mouse over the thumbnail and read what it says in the exif bar at the bottom of the screen; it's the last item in the data.
If it does not show Adobe RGB and says sRGB, it's as I said not exif tagged or embedded. Yo can override the image icc profile in the filter screen to correct it - near the bottom of the adjust tab.
This is unlikely to give a magenta cast, just make the image look dull overall.
Terry

Yes, the filters have unique names and were saved.
You don't see the tick because I wanted to double check the M-60 print, so I removed the filter and re-printed.

I am sure it *should* work fine.
I like the quality of the prints, but because I did not get the same colours printing a large format in a lab, I had the monitor calibrated.

I know I could pop in fresh inks to restore the original quality, but I am just puzzled that I cannot tweak the colours with the filters.

Do you see a difference in the image on screen when you make the filter?
Terry

no, I don't.

If the sky is basically neutral then a magenta saturation of -60 probably will not make much difference.
Could you see the difference when using the White Balance changes?
I tried your values here on an image with a grey sky and the difference was considerable. I'm confident enough in my process to know that a print would reflect this.
I see from your screen shot that it is some time since your monitor was calibrated - probably worth doing again. How was this done before?
Terry.

Terry, Gian

Perhaps Gian can email the image to you...... problem solved in 5 minutes!!
Also, turn off the Monitor profile, select a pixel in the Qimage editor and read the RGB values. Write them down.
Look at the lower right in the Editor for Pixel position. Select (example) 2000 x 200. (Easy to remember.) That should put you in the sky.
Write down the RGB values.... Now turn on the Monitor profile.
Do the same test on the same pixel, 2000 x 200.
Write those numbers down.
What did you get?

Fred

I've e-mailed Gian with my address.
Terry

Fred,

I can't seem to find an editor with a colour picker tool, are we talking about QI-Pro?
I have setting to define an external editor, that's it.

Terry,

I don't know why the monitor profile was named like that, but I am sure that the calibration is not older than 10 days.

Will try Fred advice as soon as I work out where is the Qimage editor...

The oldest I have is an old Studio, but fairly certain you have the same interface in PRO
See screen snap.
Open the Editor screen to the tools as shown.
At the bottom of the tool box, you see Pixel Position and Current Color

Fred

I'm really puzzled now! You've said you had made a filter already - that is the editor.
Right click on the thumb or add to the queue, right click on the image on the page preview and choose batch filter.
The terminology for Qimage Ultimate is now image editor, it used to be create filter, it's the same thing. The editor makes a non-destructive filter to edit the image.

Any more thoughts about letting me play with your image, I sent you an e-mail. We could then solve this very quickly I'm sure.
Terry

ah, yes! ok, I was looking for Qimage Editor in the menus and couldn't find one...
Please bear with me!

I sent Terry a link to download the image, with the resulting values for pixel 1700x1200.

Thank you Gian,
I have been in contact with Terry as we usually do when trying to help.... he sent your image ti me.. I get the same numbers that Terry gets.
If you are using Epson Paper and Epson ink and an Epson profile (the correct one for the paper and printer),
You should not get a magenta cast.
If you do, try a head alignment run using the utility in teh driver, and then another cleaning cycle.
My printer has the flu, and Terry is making the test print, same printer that you have.

Best
Fred

Yes, those numbers are just on the warm side of neutral: RGB 218, 209, 195. Gian's numbers were 224, 212, 197, just a little brighter.
I did 2 test prints, one on Ilford Smooth Gloss with a custom profile and one on Epsom Premium Gloss with the Epson profile. Both prints are pretty well identical, no magenta cast and the area where we checked the RGB values looks just a little on the warm side of neutral as expected.
I agree with Fred, you need to look at your printer.
Terry

I think Gian used a different program to pull out the RGB values, so that might explain the different pixel values

now that I know where to look for, I will double check the pixels with Qimage Editor...

I strongly recommend that you also do this with the monitor profile turned off. That way you get the true values for the image and not altered by the monitor profile.
Terry

I was not able to get on the same pixel (cheap mouse?), but at 1702x1202 I get:

with monitor profile
222-211-198

without monitor profile
222-211-197

it seems that there is no influence.

I do not know if it is relevant, but I run Qimage inside a virtual XP in a Linux Ubuntu box.
The monitor profile is loaded in Ubuntu.

-G

Just curious! How was the monitor profile made?
I think I saw it listed in Job Properties in Qimage, so Qimage should be utilizing it.

Fred

well, frankly I don't know how the monitor was calibrated.

It all started when I wanted to have one of my shots printed at a fine art shop.
The colours came out different from my prints, and they suggested to calibrate the monitor.
Because they serve top professionals, I trusted that they knew what they were doing.

Now, the calibrated monitor is a NEC driven by an HP notebook, and connected to a docking station.
I notice now that I am away from my desk, (and btw in front of the panorama you have printed), that the notebook has EXACTLY the same pixel value of the NEC.

How can this be possible.
I wonder if the combination of external monitor and Virtualbox has messed everything up.

In the end, my printer may have clogged/dirty nozzles, but I can't understand how one can tweak Q-Pro to adjust colour bias, if my settings do not change neither on screen nor on paper.

I just Googled Ubuntu Color Managment, looks tricky.  :o
A question that needs to be answered (i can't): is colour management and the use of a monitor profile active in Ubuntu and/or is it active in XP in your virtual PC? Is the monitor profile activated on PC start-up and working with video card to make the adjustments from the profile look-up table?
It could be Colour Management is not working at all in the virtual PC.
Terry

It seems to me, Gian, that somewhere you got bad information.
I am going to break apart the above quote.

"It all started when I wanted to have one of my shots printed at a fine art shop"
They made prints for you!

"The colours came out different from my prints, and they suggested to calibrate the monitor."

Your prints came out with different coloration, and they advised you profile your monitor.
Did I get it right?


The monitor profile has nothing to do with the prints at all. Nothing!  You can borrow a friend's monitor, or buy a new one, or shut it off when ready to print, the prints will be the same each time.

The only time the monitor profile comes into play is when you rely on it to adjust the image (darker, lighter, sharpen, etc.). Then you are adjusting the image based on a correctly adjusted monitor.
If you didn't adjust any colors on the image, then the monitor will not affect anything in your print.

So back to basics. The printer is defective. The printer profile is not correct for the paper. Your driver selections of paper and No Color Adjustment set in driver may be missed. etc.

Sorry, but that's what I come up with...

Fred

Fred,

of course the monitor has nothing to do with the printer, but the calibration - as I understood - is the way to go to TALK the same colours with the print service.

I might be happy of my prints even if they are wrong, but if I want THEM to print the same colours as me, we must start with what we see on the screen.

I agree that something must be wrong with the printer, and probably I should invest in new inks even if they are not empty, but still, when I'll have a printer reset to factory defaults, I must find a way to tweak Q-Pro to obtain the colours I want, and have them printed by the lab.

I do not quite understand, in QI Ediitor, what is the filtered<->unfiltered slider for.
The label says it is for red eye correction, or blemishes.
If the slider is half way, I can see the filter effect of, say, a blue saturation of -77,
Because it is very subtle, at first I had a hard time to see any difference.
Is this how colour filtering works?

That is the Filter preview window. The slider splits the window so the filtered (= adjusted) image is shown to the right of the slider and un-filtered to the left.
Having the split helps you to see the difference the filter makes - not always easy! It is helpful to increase the magnification sometimes and choose a suitable area of the image to see the differences. Right click on the image in the editor to select an area and open the preview.
The Blemish/Redeye feature is activated in the preview window it is not related to the slider which should be over to the left when being used.

From what I can see there is nothing wrong with your image, it prints fine here and from what you say the prints you make are ok. too.
I think we may have misunderstood; it's the Print Service prints that are wrong, not yours - have I got that right?
If that is the case, it's the Print Service problem and their colour management. Maybe they can't handle images that are Adobe RGB and assume all is sRGB? Are they a "high street" service or a professional lab?

One other point, if you are modifying and image with a filter for the print service to use, you'll have to save-as ...  from the editor to incorporate the filter adjustments. You can convert to sRGB there too.

Terry

Terry,

thanks for your patience...


well, in a way, none of the prints are "right"... they just don't match.

The problem is that I had the insane idea of printing a few of my "masterpieces" (!) on fine art paper, 5 feet large.
Because I live close to the photo fashion district of Milan, the labs are used to serve top professionals, so there is no question about their ability.
The first test I did, came out quite different from my prints, so before investing $$$ in this venture, I said stop! let's find out a way to talk the same language as the lab.

I must confess that my prints never really matched perfectly what I saw on the screen.
I thought that the difference was due to the fact that the monitor is backlit and you look at the prints reflecting artificial/available light, but as long as I was happy with the result, I did not care too much.