In Camera, In Computer


This article was submitted to the Photographic Society of America in the Spring of 1998. It was never published, possibly due to the fact that they found out I was not a member.

I love color. Loud, bold, screaming color. When I can't get enough of it from over the counter film and filters, I turn to posterization.

To a novice, my definition of posterization is to separate an image into light, medium, and dark tones, then replace each tone with a color. This is (or at least was) accomplished in the darkroom using lith film and a good registration system. The process isn't overly difficult, but it is tedious. I would spend many hours over several days before I could see the final result. But even though I loved this creative control, I just did not have the time to do very many.

Then in 1996, I started hearing about digital photography. Curiosity peaked, I wanted to find out if it could simulate my darkroom posterizations. So I had a few of my slides scanned onto a CD ROM, took it to work, and played Adobe Photoshop on my lunch hour. By the end of lunch, I had nearly recreated a posterization that took me weeks to perfect in the darkroom. Plus, there was nothing to clean up or chemicals to dispose of! I was hooked. Within months, I had my own digital darkroom and I haven't looked back.

Today, if you're trying posterization for the first time, chances are you will be doing it on the computer. But my "how-to" still begins in the darkroom. It helps define the technique of replacing tones with colors. So let's turn the following B&W image into a color posterization, first in the darkroom, then on the computer.


In Camera Posterization

EQUIPMENT: B&W darkroom (lith film & chemistry), a camera with double exposure capability (I use a Nikon FM2), a close focus lens (I use extension tubes), a rigid copy stand, a registration system (I use a 2 hole punch and registration pins), a copy / light box (I made my own), and a color light source or color filters (I use my dichroic enlarger head).

The general idea is to separate the image into tones by enlarging it onto high contrast lith film, replace the tones with colors, then reassemble the colors onto a single frame of color film.

With the darkroom set up, the first thing I do is pre-punch a supply of 4x5 lith film. I have found out (...the hard way) that it is easier to make every exposure (enlargement and contact) on the registration pins than it is to register the film later.


Using the enlarger setup below (...registration pins securely taped to the easel, which is securely taped to the enlarger baseboard)...


Enlarge a series of positives, light to dark, onto the lith film (on the pins, and move nothing between exposures to keep registration!). After processing, select 3 or 4 positives which show a good tonal separation.


Next, contact each positive onto a sheet of lith film (...on the pins), creating a series of dark to light negatives.


Next, assemble the positives and negatives as shown below. This is the tone separation. Notice that any given area in the image is open (clear) in only one of the separates.


Pick a color for each tone...


Finally, expose each color (...on the pins) onto a single frame of color film. This is accomplished with the camera (loaded with color film) mounted on a copy stand, with the copy box / pins / color light source securely mounted directly underneath it, as shown:


Place the first lith tone separate [NEG1] on the pins, add the first color, lights on, and trip the shutter. Next, recock the shutter without advancing the film, place the second separation [POS1 + NEG2] on the pins and expose. Repeat these steps until all colors are exposed onto the frame of film. Then finish the roll and process. Viola, posterization!


You may have noticed the considerable time investment to this point, yet we have no idea what the posterization looks like until the film is processed. I've taken dozens of images through this process only to give up all hope on it when the roll of film comes back. What I wouldn't have given for a way to know what the posterization would look like in a few minutes instead of days.

Good news posterization fans...

In Computer Posterization

EQUIPMENT: A computer (I've done this on several computers from a Pentium 60 with 16 Mb RAM to a Pentium 4 2.4GHz with 512 Mb RAM), Adobe Photoshop (...I've used versions 3 through 7), a way to get your photographs into the computer (scanner or scanning service), and a way to get your images out (a color printer for prints, or a CD-R or zip drive so you can send them to a digital printing service for slides). (Note 5-25-08: Photoshop Elements will work too).

Although Photoshop has filters that can create instant posterizations with the click of a mouse (...and they are worth trying!), I still most often use the technique of replacing tones with colors. The biggest difference between the darkroom and computer is that I do not have to create a tone separation. I can directly replace, or "paint" the tones.

After opening a photograph in Photoshop, first change it to Grayscale mode [IMAGE > MODE > GRAYSCALE]. Your image is now 256 shades of gray. Essentially it is not continuous tone at this point, but a 256 tone posterization.

Next change the mode to Indexed color [IMAGE > MODE > INDEXED COLOR].

Then call up the color table dialog box [IMAGE > MODE > COLOR TABLE]. The color table will pop up, showing you the 256 tones.


All you have to do now is start painting.

To recreate my darkroom posterization, I want to replace the darkest tone with green. Using the mouse, click and hold on the darkest square on the color table, then drag to highlight the darkest few rows. When the button is released, the color picker pallet appears. I pick green, then OK to begin the range, then OK again to end the range on the same green (note - you don't have to begin and end on the same color!). Then click and drag the next range of squares and fill it with blue. After painting the final two tones in the same manner, hit OK and the color table is applied to the image.


If you don't like it, try another pallet. Or another. (Tip - you can save Photoshop color tables, so as you start building your library, you can quickly apply them to new images).

Poster 2

Poster 3

In the same time it used to mix the developer for the In Camera method, I can now rifle through several posterizations. With 256 tones to paint, the control is phenomenal!

And sometimes that's just the beginning. After creating a posterization, turn it back to RGB mode and start applying Photoshop creative filters, or montage it with real images. Experiment. Get loud. Go completely wild. But most of all, ENJOY!


I hope it inspired you to try it. And I hope you WON'T stop there. I have taken my own advice from the final paragraph, and have wrote another article on taking the images One Step Further. I hope you'll visit that page.

Finally, people ask me "What kind of images work for posterizations". Frankly, I haven't found the magic equation. I live by trial and error. I mostly look for strong graphic images, but I've had textures that worked, out of focus areas, faces, double exposed faces (...hey, if you're going to work with weird colors, why not try weird images too?), and even an occasional landscape (...please see my Delicate Arch posterization in One Step Further). The only advice I can offer, and I know it sounds strange in light of the loud colors, but you really have to think in B&W. Remember, you're dealing with tones first, THEN replacing them with colors. One more hint - if you get the sun in the picture, you'll have a great range of tones to separate (...remember the lead photograph of Sun Tree?)