Color correction agony

[John C Murphy]

I am still having problems obtaining accurate colors in my scans of my slides (120 and 4x5). While I can get close, the scans rarely look as good as the originals. I have tried three different scanners (Epson, Minolta, and Canon)-they don't seem to be the problem. I have tried various profile makers (Monacco, lcms, Silverfast)-they also seem to be equivalent. The automatic color correction on Photoshop also works well, but again, it is never perfect. So what next? Switch to MAC? I understand color management is somehow easier on a Macintosh. What do you folks recommend?

[Ken Lee]

Your monitor must be calibrated to a known standard. Every unique combination of paper and ink must be profiled with a sensitometer. Every different brand of has its own color imbalance profile. Addtionally, the color temperature of the lighting has a big influence., so each image is different.

If you are posting here, you are probably interested in a high level of image quality. Every now and then, someone comes along who says that they get great results just using the equipment right out of the box. I am skeptical. Keep in mind that Graphc Arts people do this soft of stuff all day, and it's a science.

One short cut is to use a standard color target, and make 2 of everything: one with the target, one without. Since you are dealing with old photos for which you can't do this, then try to find a region that is grey, and use the grey balance tool in your image editor.

Changing to a Mac is not the answer, in that the tools are there in the Windows versions as well: but you need to learn how to use them.

Anbother important thing to know is that it's not enough to make visual corrections in a standard color space. Photoshop gives you the ability to preview according to the output color space of any device you like. For example, if I make my image look great in my printer's color space, the print will look fine. If I view the same image in a web browser, it looks quite different. That's because the browser has its own color space. Again, Photoshop's ability to let you see images in different color spaces, is vital.

[julian_4860]

I agree with Ken, everything a Mac can do so can a PC these days. PCs used to have a problem with how they read icc profiles but no longer. Before giving up here's what I 'd do:
profile you monitor, standardise your colourspace - adobe rgb would work fine, get custom profiles made for each different film stock - forget the approach of using a scanner as a measuring tool, it won't work, so either buy a profile making package or get someone to do it for you (if you only use a couple of films its much cheaper to paysomeone) don't use anything in the software on 'auto' - set everything up.
The key to all this is custom profiles, having profiles made of YOUR film stock on YOUR scanner, not an average

[John C Murphy]

Good so far, but I guess I'll need more specific advice concerning which profile software to use. The Monacco EZColor really did not work as well as I would like (too inflexible?) so I got rid of it. The free shareware from www.coloraid.de also is problematic. Do I need to spend a couple thousand dollars for the full package from either Macbeth or Monacco?

[Ken Lee]

Oops - Sorry for the error: I meant to write "Every different brand of film has its own color imbalance profile."



One place with which I have been lucky, is <a href="http://www.chromix.com" target="_blank">ChromIx<a>. They made me a very good profile for my Epson 2200 and Enhanced Matte paper( note: each ink/paper combination has its own 'personality'), and they gave me good advice on tools for monitor calibration, etc.



I stick with one paper/ink combination, which makes things easier. Since my images are intended for viewing behind glass, I use a Matte paper: since matte papers are claimed to have greater longevity, and once behind glass, I find the extra shine, when visible, to be a visual distraction that does not contribute to the dynamic range of the image.

[Ken Lee]

Do I need to spend a couple thousand dollars for the full package from either Macbeth or Monacco ?



It depends on whether you want to get into the printer/ink profiling business. If you only intend to print on 1 paper/ink combination, then for $99 you can get a custom profile made by someone with top level equipment and experience. The Gretag Macbeth monitor calibration tool is a good investement, for a few hundred dollars. You can use it forever, or at least until these things become obsolete. So hopefully, you can divide your estimate by a factor of 10.

[John C Murphy]

I'd really like to know what everybody who scans slide is using for their color workflow.

[chris jordan]

I almost always find that if I get a perfect scan of my original, I don't like it because the original has a color cast (which is almost always blue). So for me, getting an absolutely color-accurate scan is not that important because the last increment of color correction is easy to do after bringing the scan into Photoshop.

Far more important to get right at the scanning stage is the placement of the black and white points for each channel, so that no pixels are blown.

[Ken Lee]

Modern color films contain dyes sensitive to 3 colors, and for each color, the response is non-linear. Film X may be a little too green in the low values, and too red in the highs. Brand Y may be too blue in the midtones, and not yellow enough anywhere else... etc. This will vary from batch to batch. Since dyes are unstable, many people store their films cool, to prevent further shenanigans of chemistry.

The lab which processes your film makes choices about chemicals, freshness, etc. - all of which have some affect on the final color balance. Of course, dyes start to fade the moment the film is developed. Printed images do the same. It's a challenge, that's for sure !

If anyone ever figures out a way to make permanent color images at affordable prices, that person will become very wealthy.

[Henry Ambrose]

John, you seem to be going at this as if you were using an "auto everything" camera and were dissappointed it didn't do what you want every time. You already know that auto focus and auto exposure don't work all the time. Its the same with your scanning work.

I suggest that you (1)pick a scanner, (2)use the software that comes with it, (3)implement color management properly for your system, (4)use something like a Spyder or similar color calibration tool to get your monitor spot-on and then, (5)learn Photoshop throughly. Its all pretty easy until that last one but you will have to put in some time to learn to color correct in Photoshop. As you work (practice) you will learn how to use your scanner's software to get as close as you can to your color choice. When this happens your time spent correcting will go way down.

Some of what has been posted earlier is good, some seems odd or wrong. Excellent scans do not come solely from machines, they come from properly adjusted machines run by skilled operators. So get your computer's color management working properly, picking a color space to work in that is adequate for your needs. Calibrate your monitor! You will then have a reasonable representation in your scanner software preview so you can get close to the right colors. Then learn how to correct color using Photoshop, viewing your progress on your now accurate monitor. Once that is done you can tackle the printing end of this thing. Final, precise corrections can only be made from the print or from very extensive experience applied by a skilled operator (and even then the print is, as always, the last word).

If the details of this seem too complicated to pick up in pieces via the net then buy a Photoshop book and follow the directions. But mostly get one set of proper tools and use them until you learn them throughly (or you are sure from your extensive experience that they are not good enough). Stop jumping around, practice, study.

Good luck!

[QT Luong]

I entirely agree with Chris, and for this reason, I haven't bothered to calibrate my scanners. I use a Photoshop action that
gets me in the ballpark before I do further color correction.

[John C Murphy]

That's been my experience as well: the monitor profile doesn't make much difference. I can turn it on and off to compare the difference and it only seems to make the images a little brighter and more vivid, but it doesn't affect the color noticably.