https://www.youtube.com/watch?v=gDz-hmidTJU&feature=youtu.be

This tutorial shows how to use a low-resolution image in a way that becomes high resolution and suitable for printing at 300 dpi. I cover converting an image from Greyscale to Bitmap using the Halftone option.  I used ‘Ellipse’ but be sure to try the ‘Line’ mode as well!

Note that changing the resolution improves the quality of the ‘screened’ image, making dots that are rounder and cleaner. This is how real offset printing works as well.

For example, a newspaper typically prints their halftone screens at about 50 lines per inch (lpi), that means there will be 50 dots in the screen per inch.

To print properly, I need to supply my artwork at  the size to be printed at 100 dpi – double the screen resolution.  Most magazines print with a 133 line screen but higher quality publications can print up to 150 lpi. Standard practice is to create/provide art at 300 dpi, which is what I did in the video above.

You can check your art size by bringing up Image>Adjustments>Image Size menu in Photoshop. While in the Image Size menu uncheck ‘Resample Image’ and type in 100 dpi as the resolution.  That will tell you the largest size it can print without re-sizing (Resampling) your image.

When the printing plates are made, the device that prints out the plate will print the plate at 2400 dpi. This means the dots of the halftone that are at 50 dpi will be rendered at 2400 dpi resolution so that the are clean and round, without stair-stepping or jagged edges.

I am using the same concept to ‘up-sample’ the original low-quality image to a high quality half-tone version of the image with nicely formed dots.