Color, brightness, and contrast correction when printing

[johns35729044]

I recently sent an image to get printed and when it came out, the colors, brightness, and contrast were all off. I want to correct for color inaccuracies before printing the second time around.

What's the best way to do this if I don't know what printer they have/are using? Nor do I know what method they are using to print the image.

All I have to go by is what the picture looks like on my calibrated monitor, and the picture I received that was looks wrong compared to the original.

Can I just adjust the original image to look the same as the printed copy, and then turn around and apply those edits in reverse?

Example:

Original picture file requires -10 brightness and -5 green color balance to look like the incorrect printed copy.

Then take the original image file and apply the reverse, +10 brightness and +5 green, save the edited copy, and send that off for printing.

Lastly, I also sent the picture as a PNG in RGB mode which I now found out was a mistake. Could that have been the problem?

[davescm]

Hi

This is what colour management is for.

A few steps:

1. You mention a calibrated monitor. Is that calibrated and profiled with a hardware device? That is the first step in getting your on screen colours accurate. Some recommend matching the white to the paper colour before profiling. Personally I use D65 but I also assess prints under daylight lamps (see step 4) so that works for me.

2. The document profile - when you send a image document for printing embed the colour profile. The safest is usually - Convert to sRGB and ensure the Save/Export embeds the profile.

3. Are you using a print firm that uses the colour profiles embedded in the image or ignores them. Ask for a profile of the printer so you can soft proof in Photoshop Also ask what profile they require the image converted to before sending to them.  If they look at you blankly - it's time to change printers.
Note though that some RGB colours will not print through a CMYK process. They are beyond the gamut of the inks. You can get an idea of this by soft-proofing with the appropriate profile.

4. Viewing. A print will look different in different lights. I use daylight lamps  to assess prints I make at home.

Dave

[johns35729044]

1. It's not calibrated with a colorimeter but the monitor is a Dell U2717D which is calibrated from the factory and has an sRGB setting built in. Not as good as a colorimeter i know but it's decent.

2. Ok, I'll looks that up on how to do that and what's involved with that. I know very little about photoshop so I'm not really sure how to make a color profile.

3. I doubt they can provide me with any of that stuff. Honestly, it's a very low budget print and the print doesn't need to be 100% color accurate.

I'm mainly just wanting close enough.

4. I'm veiwing under 5k LED bulbs with somewhat ok CRI. Not professional grade by any means but ok.

I want to stress, I'm just looking to get close enough not perfect. I have very little info about what they're doing on their end so i'm just asking what I can do to compensate for the garbage printing service.

[D Fosse]

johns35729044  wrote

It's not calibrated with a colorimeter but the monitor is a Dell U2717D which is calibrated from the factory and has an sRGB setting built in

That's Dell for you. Their advertising is full of this nonsense.

As I said, you always calibrate to something. If your prints are too dark, your monitor is too bright.

It needs to be stressed here, just to avoid confusion, that calibration and monitor profile are two different and unrelated things - but rolled together in one operation by a calibrator. So the two are often collectively just called "calibration", but they should really be referred to as calibration and profiling respectively.

The Dell factory "calibration" is really a monitor profile, not calibration. As such it's better than nothing. But the monitor itself comes fully uncalibrated out of the box and that's something the user has to do. Setting a basic temperature and luminance, using the monitor's OSD controls, is a simple and basic calibration. That's what you need to do until you get a real calibrator with a colorimeter.

[D Fosse]

Two things to consider here. One, does the printer have a properly color managed process? In the consumer segment, few of them do. They just run it through some generic process without any regard for color profiles, and the result is at best ballpark. That's perfectly fine for 99% of their customers anyway. But you can't expect accuracy.

But let's say they do have a fully color managed process. And let's assume you have too. So all color profiles - document, monitor and printer - are good. Then you need to look at your monitor calibration. Calibration isn't, and never was, a self-contained and absolute process. You always calibrate to something - a white point and a black point. That's the framework for the profiles and color management to work within.

A printed photograph, however, is a hard reference. You can't change the color of paper white, it is what it is. That's your white. And you can't change maximum ink density in the blacks, you can't make it any deeper even if you wanted to. That's your black. So you have those two reference points. That's enough, with those two fixed the rest will fall into place assuming the profiles are all good.

So here's the trick: You want monitor white to be a close visual match to paper color. You want to "see" paper white on screen. Numbers don't work here, your perception is influenced and shaped by your whole working environment, ambient light, print viewing light, right down to the application interface. It's a purely visual process. Just get them to look similar. Nevermind the numbers - if it looks right, it is right. Don't listen to anyone who tells you that you "must" calibrate to 120 cd/m2 and D65. You may end up with very different numbers.

Next, the black point. Black level has a profound impact on the perceived "punch" of an image. The problem is that most monitors have a black point much deeper than anything you can ever get in print. In terms of contrast range, a good inkjet print on high grade glossy paper has a contrast range of maximum 300:1, usually less. But monitors have a native range of up to 2000:1 or even higher.

That means you're in for a massive disappointment when you see the final printed result. It looks muddy and undefined. Much better to set that black level in calibration, so that you can be prepared and compensate.

With proper white and black points set in calibration, you have the holy grail: what you see is what you get. You often hear that "print and screen can never match". That's not true, but it does take a little tweaking to get there.

All this is to get a basic match. Next up is proofing and gamut clipping, but that's a separate issue when the basics are in order.