When computers were new and images first appeared on computer screens, those images didn’t look like clear images on modern computers and devices. They looked quite “coarse” because they were bitmaps. Each pixel in the image is mapped to one of 256 different shades of gray or less. In the early years – from 1984 to 1988 – monitors could even display only black and white images. So every image viewed on a computer screen was essentially black and white and contained a hatch pattern.
A few months ago, we showed you how to create the Hedcut look used by the Wall Street Journal. In this How To, we’ll show you another way to create this look by creating a halftone image in Photoshop.
If you’re unfamiliar with the term halftone, this is a printing method that uses ink dots of different sizes, angles, and distances to simulate a black-and-white photo. If you want to see it in action, break a magnifying glass and check out the photo in the local paper.
The key to creating halftones in Photoshop CC is to convert the image to a bitmap and then apply a screen to the bitmap.
As an added bonus, we’ll show you how to colorize an image in Illustrator CC, a technique we learned from Illustrator guru Carlos Garro.
- Add black and white adjustment layer
- Convert to bitmap
- Adjust resolution
- Colorize a .TIFF file in Adobe Illustrator CC 2017
Add black and white adjustment layer
We are going to work with a cow on a farm in Bern, Switzerland. The first step in this 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 color channels and their contrast to grayscale. For example, the cow in the original image has brown fur. To add detail to the fur, the red slider has been moved to the left to make it slightly darker. The sky is blue and to give a little more contrast between the sky and the white face of the cow, the blue slider to the right has been moved to white.
If you want to add a little more contrast to the image, add a Levels adjustment layer and, paying attention to the details, move the Black slider to the right and the White slider to the left.
Convert to bitmap
Our ultimate goal is to convert the image to bitmap format. This format reduces the image to two colors: black and white. if you choose Image † Mode , you will see that Grid mode is not available. The reason is that if you look at the menu, Photoshop still considers the image to be in the RGB color space.
To convert, select Image † Mode † shades of grey † This converts the image from the current color format and replaces the RGB color information with grayscale. This will lead to a warning that changing the mode will remove the adjustment layers and ask you if you want to do that or smooth the image. Select Flatten †
You will then see another warning asking if you want to remove the black and white adjustment layer and color information from the image. Click Cancel † If you return to Image † Mode , you will see that the bitmap is now available. Choose it.
When you choose Bitmap if image mode opens a dialog bitmap asking you to make some decisions.
The first is to decide which image resolution to use. While the golden rule is to never increase the resolution of an image, this is one of the rare cases where increasing the resolution value has no negative effect on the final result. In the case of this image, the resolution has been increased to 200 ppi.
The next question is which method to use for the conversion. The drop-down menu has several options, but we’re going to create a halftone effect. What does it do to turn the image into a series of dots. Select halftone screen and press OKAY.
When you press Okay in Bitmap dialog box , a second dialog box opens. This is an important dialog box.
The frequency value, in the case of this “How To”, will determine the size of the dots. we used 15 lines per inch †
Meaning Injection is what you may have guessed. This is the angle at which the points are placed. For example, a value of 0 will align all points in straight lines horizontally or vertically 45 †
The shape of the drop-down list determines which point types to use. For this exercise we chose: Round †
Click Okay and now you’re looking at a “retro” bitmap.
For more information about bitmap mode, see Photoshop’s help documents.
At this point you can save the image as jpg or .psd. Since this image is for Illustrator CC, we saved the image as a .tiff file.
Colorize a .TIFF file in Adobe Illustrator CC 2017
One of our Photoshop tutorials will show you how to turn a photo into a Roy Lichtenstein comic. This technique is a variation of a technique that uses a bitmap instead of a color image.
To add color, the Cow.tif image was opened in Illustrator CC. The reason for this decision is that the .tif format is a pixel-based bitmap format and points can be colored using the Color panel in Illustrator. Here’s how:
When the image opens in Illustrator, select it.
Open Color panel and choose a color from the palette. Each time you click on a color, the image changes to that color.