505 - 1 - Halftone Experimentation

Before I began experimenting with the layout on Illustrator, I looked into the process of bitmapping and the different effects it can have..

Bitmapping an image ready to screenprint
Bitmapping involves transferring the gradients into your image into halftone dots. Halftones are named by the number of dots used per inch, this is the halftone frequency. While the size of the white and black areas in a Halftone pattern changes, the number of dots per inch remain the same. The halftone dots create a pattern of light and dark . Overlapping halftone patterns can be rotated to reduce interference, or moire. The degree of rotation is called the Screen Angle.


Halftone dots and Grayscale

Frequency
The size of the dot used is determined by the screen printing mesh. For simulated process and process printing it is best to keep the dots as small as possible, so using a fine mesh is best. Mesh counts between 195 and 355 are common, using halftone dot frequencies between 40 and 65 lpi.

To determine the halftone frequency divide the mesh count by 5

Increasing the mesh count can help to reduce moire.
• Underbase – use a 195 mesh with a 45 to 50 lpi halftone.
• Colors – Use 230 to 305 mesh with 50 to 55 lpi.
• Black and Highlight – Use 305 to 355 Mesh with 50 to 65 lpi.


Halftone dots overprinted at various angles

I took what I had learnt and began do abit of my own Halftone dot experimentation with images of Headrow House.

This first experiment made me realise how I could not use an image with as much detail and depth, as the half tone simplifies the content quite a lot. 

I experimented with an image I took within the event room in headrow, as the distinction between light and dark was more simplified. This one came out nicer and the dot frequency was more flexible and responsive when finely tuning it I found.

I took a fresh picture of the sign outside Headrow, considering how the plain blue sky should allow for all the attention and detail to be put on the building/sign.

I found the first experiment quite difficult as it was still quite detailed, however when I lessered the frequency and zoomed the bitmapped image in the dots became larger making it more appropriate for the mesh when I screenprinted it.