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Author Topic: Can scanning a test print into Vuescan guide the final adjustments needed ?  (Read 11735 times)
tonygamble
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« on: January 27, 2013, 10:37:52 AM »

When you have scanned an image in Vuescan the Color Tab enables you to see the RGB figures for any part of the image.

It would take no time at all to scan in the latest test print.

I wondered if this might help in the process of editing a Profile?

Inevitably experience improves the accuracy of eye-balling the test print but for newbies like myself seeing, for example, what was wrong with a grey scale might speed up the correction process.

Is this a wild goose chase or something worth exploring further?

Tony
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Fred A
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« Reply #1 on: January 27, 2013, 11:36:31 AM »

Quote
It would take no time at all to scan in the latest test print.

I wondered if this might help in the process of editing a Profile?

Tony,
Terry is much more knowledgeable than I with scanning, so I know he will have some sharp data for us, but just from my experience, the main problem with scanning targets or anything that will be used as a benchmark is the scanner's light source/color temperature and metamerism.
That's the main reason Mike recommended the Canon LiDE scanner because of the "cold light" source.

So, off the top of my head, sounds like opening a can of worms with no expectation of good results.

On the other hand, I get the feeling that you are not using the editor in correct fashion as it will allow tweaking your profile with super results.
For example: you can tweak flesh tone, without effect on trees, and tweak the green/yellow foliage without any effect on flesh tone.

The procedure is to match the right side of the editor (which has two screens) to the print you made of a standard image (Digital Dog or whatever you like) by adjusting sliders of the various controls until you make the right side screen match the print.
Then you make your corrected profile, and make another print. Let it dry a bit and cure the colors, and now compare it to the reset right side which matches the left side.
It should be very close, another final tweak; maybe a touch less saturation or more brightness?   You still do this by making the right side match the latest print; not by moving sliders the wrong way.
Last hint is to make prints, and subsequent prints. Softproof is not a substitute for a real test print.

Maybe this helps??

Fred
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tonygamble
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« Reply #2 on: January 27, 2013, 12:54:38 PM »

"On the other hand, I get the feeling that you are not using the editor in correct fashion as it will allow tweaking your profile with super results. "

Not so, Fred. You are a splendid tutor.

But remember when, having used No Color Adjustment, I got rid of the yellow tint on the flesh tone I felt that the lady's jumper was 'weak'. I use weak deliberately as it can mean different things to different people.

I was unsure whether it needed:
More red.
More magenta,
More saturation.
Less brightness.
More contrast.

I realise the numbers for the RGB only show the first two possible modifications - but that's a start.

I realise that altering the jumper should leave the grey steps unchanged but what do I do if those look a bit 'Warm'. It would be great to know whether I need more blue, less red, or whatever.

I accept the point that the scanner itself may have its own colour cast - but felt the point was worth asking.

Thanks again for your response.

Tony
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Terry-M
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« Reply #3 on: January 27, 2013, 03:11:27 PM »

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It would take no time at all to scan in the latest test print. I wondered if this might help in the process of editing a Profile?
I'm not sure that it will and could confuse the matter. Would you allow Vuescan to modify the image or use the raw version? I wouldn't know. I find that scans from a print are generally lower in contrast than the original so that will affect RGB values in addition to the scanning process modifying colours.
After all that, I cannot see how that data would help within PP.
Remember that in the PP editor, the image on the RHS has to be made to look like the print so it's a sort of reverse process. Therefore using data from a scan would be difficult to interpret.
The PP editor has a colour circle (I recommend using the wizard dropper) so that shows you where a particular colour is on the circle. The editor is very much a visual editor but if you want to read the RGB values in PP, use a tool like Color Cop to do that; that will give you the numerical balance of RGB values but I'm not sure how useful that really is.
Quote
I was unsure whether it needed:
More red. More magenta, More saturation. Less brightness. More contrast.
That come with practice but a good understanding of the physics of light & colour may help.
The beauty of the PP visual editor is that the latter knowledge is not essential and trial & error can be used - as long as the RHS ends up looking like the print.
Don't forget to illuminate the print with either good daylight or a proper daylight source like an Ott-lite.
Terry
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tonygamble
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« Reply #4 on: January 27, 2013, 03:19:09 PM »

OK, Terry.

I'll let the matter drop, but I needed to ask.

Have you come across any useful URL's or YouTubes that demonstrate the physics of light & colour. My wife is a watercolour artist and spent hours being taught colour wheels.

By coincidence her class last week involved making a black, white and grey painting but using coloured paints.

Anything I could read or watch to speed the learning curve?

Tony
 
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Terry-M
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« Reply #5 on: January 27, 2013, 05:19:45 PM »

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My wife is a watercolour artist and spent hours being taught colour wheels.
Be careful, artists have a different view of colour and what colour is made when they (paints)are mixed. It is not the same as light.
Artists tend to think, for example, that yellow is a primary colour, it's not. Yellow light is made from Red & Green.

I have not used PP for a while for a printer profile so just for fun I resurrected some scanned targets fro PP and re-made a profile. This was for Ilford Smooth Heavy Weight matt. Except for some saturation increase needed on the print, colours were good and greys perfectly neutral. I had the bear in mind that a matt paper does not produce particularly good contrast or saturation.
Terry
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tonygamble
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« Reply #6 on: January 27, 2013, 05:45:50 PM »

Yes, I remember seeing a video about the difference between the way paints and light make colours. I also dug out one of those packs of six filters I have from my neg/film days when one had to colour correct prints for an enlarger. It might be useful - or useless.

You mentioning a matte paper profile is a coincidence. I have not printed matte for ages as I have never updated my profile when I moved from the 2100 to the 2400 Epson. Hope my matte ink is still liquid. It is quite old.

Tony
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Terry-M
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« Reply #7 on: January 27, 2013, 08:54:58 PM »

Further information re:
Quote
I have not used PP for a while for a printer profile so just for fun I resurrected some scanned targets fro PP and re-made a profile
Again, just for fun  Roll Eyes I made 2 prints on an A4 page of 4 images, including "real world" images. One was with my PP profile and the other with a "proper" custom profile made my my local colour management company with their top quality, Multi £'000 equipment.
Even I was surprised, the PP profile was just as good, the prints had more "bite" and excellent colour. I could probably afford to reduce the contrast a little, that's all.
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Fred A
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« Reply #8 on: January 27, 2013, 09:04:56 PM »

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Even I was surprised, the PP profile was just as good, the prints had more "bite" and excellent colour. I could probably afford to reduce the contrast a little, that's all.
I got exactly the same results.  I redid the same profile (not editing just recreating) using a -2 saturation on the front panel.
Fred
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