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Author Topic: How can I get rid of "burple" shadows?  (Read 6815 times)
Mack
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« on: June 30, 2013, 09:41:35 PM »

I seem to have some issue where my gray step-tablet gets more blue-purple (hence "burple") as it goes to the black side of the scale when printed.

Is there a way to correct the linearity of the blue/magenta somehow to counteract that easily in the Editor?

Does changing one color in the Editor move everything linear with regards to both ends of the step-tablet?  I need to get rid of it once it begins building to the shadow side and leave the whites alone.

(E.g.  "Can I maybe change the Editor's color selection "N" and Magenta and Blue settings to 0.96 to get more green and yellow into the shadows without affecting the white to any degree?"  Then Save and apply it as a "Print Filter (or "P. Filter") since that seems to be the way my "ColorMunki Photo" profiles turn out in general.  Maybe a bit more Contrast and Brightness too for the saved "P. Filter" too.

..if this makes any sense.

Tia.


Mack
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vsteffel
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« Reply #1 on: July 01, 2013, 02:00:45 AM »

Sounds like purple fringe.  Can you attach a photo that shows the problem you're trying to correct?
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Mack
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« Reply #2 on: July 01, 2013, 02:53:32 AM »

Nope.  It's not fringing.

It's an overall purple color cast once the step-tablet's steps approach black.  See the image with the step tablet applied to the side and the RGB values in it.  Of course, it is a JPG and now probably in sRGB vs. original Adobe RGB 1998 TIFF file so the values may be off when seen or read now.  They were painted onto the print with PS "Bucket Fill" for the given values.

More odd, out of the Canon 9000 II printer it is really "burple" near the upper end of the scale.  Later on, I tried same print off the Epson 3880 (pigment) and it is almost neutral gray overall.  Seems odd, but even the 128 value in QU for the border is very different in color between the two printers.  I don't think it's possible to change the QU border default 128 gray over what the Editor part if it does to the image within that border 128 alone?

The calibration and ICM profile was made the same way for both the Canon 9000 II (dye) and Epson (pigment) off the ColorMunki Photo onto the same Canon Glossy II paper.  Something is different that the unit makes for a profile between the two printers.

More odd is the white off the Canon is not white, some shade under 255 values, maybe RGB of 240, 248, 250 or so.  Off the back of the paper it is more even at 245 when read on the CM Photo.  I suspect there is something going on with the UV brightners in the paper's surface when the CM Photo reads the inks.  Possible that the CM Photo is reading through the dye ink on the Canon and influencing the blacks to be "burple" on it?  The Epson pigment 'paints' the surface so the UV brighteners may not be as prevalent in the CM Photo's ICM making process?

So Adobe 1998 RGB 255 "White" depends on the paper base (Here about RGB 245), and maybe the paper's brightners influence the CM Photo too.  Black, with Canon dye, might be reflecting back some UV brighteners and messing up the profiles?  Epson pigment painting over the paper's UVBs makes for a more true profile?  I dunno.

Fwiw, the Canon produces more depth on a glossy print being dye.  Has more gloss overall too over the Epson 3880 when held side-by-side.  The dye has a bit more contrast too.  Epson has a better (even) flesh tone - so far - and better gray scale reproduction as well.  I had to drop the Epson "Brightness" in QU about -3 points, and jack the "Contrast" up about +4 points over the Canon's settings to make them appear similar.


Mack
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Mack
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« Reply #3 on: July 03, 2013, 02:23:43 PM »

Switched paper brand to Red River and did a profile with the ColorMunki Photo.  Much better gray numbers on the Canon 9000 II dye printer than I was getting with the darker "burple" coloration on the Canon Glossy II paper.  I do not see the burple shadow issue with the Red River paper now.  Epson pigment is the same so no change with it.

I suspect it is the optical brighter in the Canon paper causing my issue with the ColorMunki Photo and the transparency of the dye ink verses pigment on that paper.  I am getting a x-rite i1 Photo Pro 2 unit next week to replace the ColorMunki Photo which I suspect has issues with the Canon paper's UV optical brightening agent.  Supposedly, it can handle the UV brighteners in paper better - supposedly.

Quite maddening watching the RGB 128 border in QU be so different in profiled papers and printers.  Putting that silver/gray border on a print within QU is very telling.  Should appear the same, or so I would think.

I noted in the test image above that the 3D shadow going off into the white border of the floating image will show a coloration in the gray shadow if something is off too.  Should be a smooth gray transition once printed.  Mine had a magenta/blue shadow off the Canon 9000 II with Canon's Glossy II paper and the ColorMunki Photo doing the profiling.  Epson looked much better in that shadow area no matter the paper, perhaps painting over that UV brightener.


Mack
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Mack
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« Reply #4 on: July 09, 2013, 08:18:49 AM »

Success!  Smiley

The new "x-rite i1 Photo Pro 2" got rid of my "burple" shadows with the Canon 9000 II and Epson 3880 printer both.  It scans 800 targets off two 8.5x11 inch printed pages, and does one scan in a reverse pass for the UV optical brightener in the paper.  All well now and the RGB 128 border in QU is within a couple of points and same for agreeing between the two prints as well.  Skin tone looks better off both as well.  It also allows one to use whatever light selected for viewing prints to be factored into the profile making process as well and shows the spectrum of the viewing light as well.  Only issue was there is some small yellow tag under the scanner that reads off the ridges on the ruler's guide that I forgot to take off so I had issues reading the target until I discovered it and removed it.  The monitor scan and setup takes about 7-8 minutes over the one minute of the ColorMunki Photo so it must set it up a bit better too in the monitor profile.  Scan process is slower though, and no 9 minute dry-down timer as with the ColorMunki Photo.  Very nice padded carry case too for all the stuff.

The ColorMunki Photo just had issues with some paper's optical brighteners I guess (esp. Canon Photo Paper Plus Glossy II).  Close, but not close enough for me.   Sad
 

Mack
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