Toning Digital Prints

by Paul Butzi

Introduction

When I started making digital inkjet prints of my photographs on my Epson 9600, my very first task was to achieve a perfectly neutral print - that is, one which was a neutral grey all the way from the highlights down into the deepest shadows.  With the aid of the excellent profiles made by Bill Atkinson (and given away for free by him, thanks Bill!) this was surprisingly easy.

Using those profiles, the first digital prints I made were perfectly neutral.  Sure, under warm light they looked a little warm.  Under cool light, they looked a little cool.  But I was pleased that I'd escaped one of the big problems of digital printing of black and white prints - namely, unwanted color shifts along the tonal scale.  Way back when I first tried digital printing with an Epson Stylus 800, I got pink highlights, green midtones, and cyan shadows - it was terrible.  It turns out that your eye is absolutely stellar at detecting subtle color shifts in a black and white print.

I hadn't made very many digital prints on my 9600 and compared them to silver prints of the same images before I noticed a problem - that perfectly neutral prints looked peculiarly lifeless.  They were 'flat', not in the low contrast sense but in the sense that they didn't have much sense of depth.  The prints made on Ilford Multigrade IV, which I'd thought of as being 'neutral', are anything but.  Sure, the paper base is cool, but the midtones are warmer.

After carefully comparing digital and silver prints which were as closely matched as I could make them, I concluded that the problem was that the prints were TOO neutral.  This was a problem I'd noticed when preparing my photos for web display, too - on a good monitor, they were perfectly neutral grey but they looked a little lifeless. 

This image is neutral
 
This image has warm midtones, neutral highlights

It turns out that although we think of black and white prints as black, white, and shades of grey, it's the subtle color shifts that add life to the print.  Yes, I thought that color shifts were a problem when I started, but the problem isn't color shifts.  The problem is really a matter of uncontrolled, inappropriate color shifts.  What I needed was a way to control color of monochrome prints.

So I started to search for a solution.  Fortunately, Photoshop makes it easy.

Solution #0 - Duotones/Tritones, etc.

My first attempt to add tonal shifts to my B&W prints was by using Photoshop's Duotone feature.  Photoshop comes with a boatload of duotone settings.  Alas, there's no good description of them - the names of the settings just list the Pantone colors used in the duotone, which isn't much help to me.   I did find a nice duotone setting on Ken Lee's web site.

Even worse, I discovered that when I applied duotoning to an image, bad things happened.  In addition to adding color shifts to the image, the images tonality got rearranged - that is, shadows got a little darker, or highlights got brighter.  Since I was applying these color changes AFTER I had gotten the image just the way I wanted it, this was a problem.

Even worse, if I wanted to adjust the duotone to suit each individual image, it was pretty hard to make the changes I wanted.

So I was stilling looking for a better way.

Solution #1 - Color Controls

The next thing I tried was a technique suggested to me by Denny Wagner - using the color balance controls in Photoshop CS to add a color cast to a black and white print.  Denny's technique was:

1.  Convert the grayscale image to RGB mode (image/mode/rgb).

2. Add the color cast to the image by using the color balance controls - image/adjustments/color balance.  To get a warmtone print,  click on "midtone"  enter in the above boxes   +3  -3  -12, click on "highlite" enter in the above boxes   +3  -3  -12  hit ok.  Leave "shadow" alone.

This gives you a sort of 'platinum' look - warm midtones and highlights.

Now, I had several problems with this technique.  First, the adjustments are surprisingly coarse - that is, changing the +3 in the formula to +2 makes a HUGE difference in the print.  Second, it's a tedious thing to have to make the adjustments every time I print an image.  I wanted something more controllable and faster to apply.

Solution #2 - Curves

If there's one thing about Photoshop that I love, it's the 'curves' dialog.  For years, I've thought about printing in terms of the H&D curve, so being able to make adjustments to the curves has been a natural for me as I moved into the world of digital printing.

To my delight, once you have an image in RGB mode, you can control the curves for red, green, blue, and the over curve independently.   By using the arrow keys to nudge the curves around, you can make exquisitely small adjustments to the curves.

Best of all, I was able to adjust the color curves to introduce the color shifts I wanted, and then use the overall curves to offset any shifts in tonality.

Even better, once you've made a curves adjustment, you can SAVE that adjustment to a file, and then later call up that curves adjustment and apply it to another (different) image.  This was just what I wanted!

With this method, the hard part (making the curves adjustment the first time) is more difficult.  I'll discuss that below.  The good part is that to apply the curves adjustments, you just use 'image/adjustment/curves' to get the curves dialog.  Then you click on 'load', select the file that has the saved adjustments, click on 'load', and then on 'ok in the curves dialog, and Voila!, the image is adjusted.

My first task was to create curves files that duplicated the results I got with  with Denny's technique - a relatively simple task. 

My second attempt recreated Ken Lee's 'Bronze' duotone effect as as set of curves.  At the same time, I added an overall curve adjustment to offset the change in tonality.

Next, I used the technique I'd developed to duplicate the tonality of a selenium toned print that had been scanned as a color image, and finally I developed a set of warm toned curves that I liked for the work I'm currently doing.

Finally, I found an interesting web page at http://www.digitalsecrets.net/secrets/iLiner.html which had some image color effects I found interesting, so I duplicated them as curves files.

You can download all of the curves files in one '.zip', here: curves files.zip.

Denny Wagner's Platinum Color Balance

 

Ken Lee's Duotone (balanced tonality)

 

Selenium tone

 

Slightly warm midtones, neutral highlights

 

Split tone - cold shadows, slightly warm highlights

 

Rustica 1

 

Rustica 2

 

Rustica 3

 

To download them, click on the link.  When you get a dialog box, choose 'save' and save the file, remembering where you put it. 

To apply the curves to an image, change the image to RGB, then pick 'image/adjustments/curves', click on the 'load' button, browse to the directory where you saved the curves file, pick the curve set you want to apply, and then click 'load' to open the curve file.  You should see the image color change if you have the 'preview' check box checked.  Click 'ok' to apply the changes.

How to make curves of your own

Although you can make curve sets yourself, just by tweaking the color curves and watching the effect on an image, then saving the curves in a file using the 'save' feature of the curves dialog, I've found several techniques to be helpful.

If you have a digital image that has the color shifts you like, you're half-way there.  This makes it easy to duplicate duotones, etc.  Just sample some points on the image using the eyedropper tool, and try to find the RGB values for a spaced set of densities - using the info window, I pick points that have K values of 20%, 40%, 60%, 80%, and I record the RGB values.

Then I make a new image and using the gradient tool to lay a gradient into it, like this:

Then, I place color samplers at the points on that image that have K values of 20%, 40%, 60%, 80%.  In the info window, you'll see RGB values appear for each of those color samplers.

Now, we're ready to go.  Add a new layer - 'Layer/New Adjustment Layer/Curves...'

Now we go through and adjust each of the Red, Green, and Blue color curves so that at the desired K values, we get the desired RBG values.  In the dropdown box, pick 'Red'.  Now, with the color sampler tool, click next to the sample point in the gradient that matches the '20%' color sampler - you'll see a little circle appear on the curve in the curves dialog when you click, then it will disappear.  Go and click on the curve at that spot, and Photoshop will add a 'knot' to the curve at that point.  Now you can push that knot up and down, either by dragging it with the mouse or by clicking on it to select it and then nudging it up, down, left, right with the arrow keys on your keyboard.  Nudge the spot up or down until the R value in the RBG for the 20% color sampler matches what you wrote down before.  Do the same for the Green and Blue curves, and for the samplers for 40% 60%, 80%. 

If the changes to the curves are minor, you're done.  If you made some big changes, you'll need to now go to the RGB curve and make changes until as you drag the color sampler tool over the gradient, all the points have matching before and after K values (in the info window, it appears as K: <old>/<new>.

Finally, when you're all done, remember to click on 'save' and give the curves file a name that will help you remember what this set of curves does.