How to Create a Colonized Halftone Image in Adobe Photoshop CC 2017

Original photo of a cow and the halftone version

 Tom Green

Back when computers were new and graphics were first showing up on computer screens, those graphics looked nothing like the crisp images on today’s computers and devices. They tended to look rather “chunky” because they were bitmap images. Each pixel in the image was mapped to one of 256 distinct greys or fewer. In fact, in the early days — think 1984 to about 1988 — monitors could show only black and white. Thus, any image being viewed on a computer screen was, essentially, black and white and contained a cross-hatch pattern.

A couple of months ago we showed you how to create the Hedcut look used by the Wall Street Journal. In this “How To” we are going to show you another way of creating that look by creating a halftone image in Photoshop.

If you are unfamiliar with the term “halftone” it is a printing technique that uses dots of ink of varying sizes, angles and spacing to simulate a black and white photo. If you want to see this in action, break out a magnifying glass and look at a photo in your local newspaper.

The key to creating a halftone in Photoshop CC is by converting an image to a bitmap and then applying a screen to the bitmap.

As an added bonus, we are going to show you how to colorize the image in Illustrator CC which is a technique we learned from Illustrator Guru Carlos Garro.

Let’s get started.

Add a Black and White Adjustment Layer

Cow photo with a Black And White Adjustment Layer applied to it
Tom Green

We are going to work with an image of a cow on a farm in Bern, Switzerland. The first step in the process is to add a Black and White Adjustment layer. When the Adjustment Layer dialog box opens you may be wondering why there are color sliders? The color sliders control the conversion of the color channels and their contrast to greyscale. For example, the cow in the original image has brown fur. To bring up the detail in the fur the Red slider was moved to the left to darken it a bit more. The sky is blue and to provide a bit more contrast between it and the cow’s white face, the blue slider was moved to the right towards the white.

If you want to add a bit more contrast to the image, add a Levels Adjustment Layer and, keeping an eye on the detail, move the Black slider to the right and the White slider to the left.

Convert to Bitmap

Mode menu with Bitmap Grayed out and Grayscale selected
Tom Green 

Our ultimate goal is to convert the image to the Bitmap format. This format reduces the image to two colors: black and white. If you select Image > Mode you will see that the Bitmap mode is unavailable. The reason is, if you look at the menu, the image is still regarded by Photoshop as being in the RGB color space.

To do the conversion, select Image > Mode > Grayscale. This will convert the image from its current color format and replace the RGB color information with greyscale values. This will result in an alert telling you that changing the mode will remove the Adjustment layers and ask you if you want to do this or to flatten the image. Select Flatten.

You will then see another Alert asking you if you want to get rid of the Black and White Adjustment Layer and the image’s color information. Click Discard. If you return to Image > Mode you will see Bitmap is now available. Select it.

Adjust Resolution

The halftone Screen Method is highlighted
 Tom Green

When you select Bitmap as the image mode, the Bitmap Dialog box opens and asks you to make a couple of decisions.

The first is to decide what image resolution to use. Though the Golden Rule is to never increase an image’s resolution, this is one of those rare cases where increasing the resolution value won’t have a negative effect upon the final result. In the case of this image, the resolution was increased to 200 Pixels/Inch.

The next question is what Method to use for the conversion. The pop-down has several choices but our intention is to create a Halftone effect. What this does is to turn the image into a collection of dots. Select Halftone Screen and click OK.

Round

The image is converted to a hafltone with dots
 Tom Green

When you click OK in the Bitmap dialogue box, a second dialog box opens. This is the important dialog box.

The frequency value, in the case of this “How To” will determine the size of the dots. We went with 15 lines per inch.

The Angle value is what you may have assumed. This is the angle the dots will be set at. For example, a value of 0 will line all of the dots up in straight lines horizontally or vertically. The default value is 45.

The shape pop down determines what types of dots to use. For this exercise, we chose Round.

Click OK and you are now looking at a “retro” bitmap image.

For more information about the Bitmap mode, check out the Photoshop Help documents.

At this point, you can save the image as a jpg or .psd image. Due to the fact this image is destined for Illustrator CC, we saved the image as a .tiff file.

How to Colorize a .TIFF File in Adobe Illustrator CC 2017

Tiff image has a purple fill from a selection in the Color panel
Tom Green

One of our Photoshop tutorials shows you how to turn a photo into comic book art in the style of Roy Lichtenstein. This technique is a variation on that one which uses a bitmap instead of a color image.

To add the color, the Cow.tif image was opened in Illustrator CC. The reason for this decision is the fact that the .tif format is a pixel-based bitmap format and the dots can be colored using Illustrator's Color panel. Here’s how:

  1. When the image opens in Illustrator, select it.
  2. Open the Color Panel and select a color in the picker. Each time you click on a color, the image changes to that color.​