Converting a photograph

Scan at high-rez, if you have a plate made (Polymer), Film is needed. The Processing Company automatically will screen the Image as it will contain halftone elements.

If you intend to print from a cut (Magnesium, Copper 0 whatever is the current Rage), you could use the Filters included in Photoshop to create an Image suitable for Letterpress.

Here’s what works for me. If you want to create a halftone in photoshop, stay away from the filters menu. You won’t have the same degree of control over the result. Convert your image to grayscale and then to a bitmap in the Image > Mode menu.

The program will ask you how you want to separate the information. You can choose halftone and enter your LPI and Frequency there, along with your dot shape, or go with 50% Threshold or Dither for additional options.

Your processing company can tell you an appropriate LPI and Frequency.

If you get into high end considerations, you may wish to fiddle with the brightness and contrast of your image in order to account for ink gain during printing.

James Beard
Vrooooom Press
www.vrooooom.org

If you are outputting to a device that supports Post Script processing you can specify how grayscale images are interpreted into halftone patterns in the print dialog. This gives you much more control than the bitmap function, but it will work in a pinch.

This is great folks, thanks for the input! I’ll post a photo when I pull a print!

Hi evseidl,

Another way to treat photos is to “posterize” the image and make multiple plates. I’m completely untrained and inexperienced in computer graphics, but managed to figure it out. As I recall, I first fiddled with the contrast and brightness, as James said. I was happy with the results.

Check the archives for tips on printing halftones. And if you’re printing a halftone of a house, here’s something for inspiration (look especially at the “original” size).

Barbara

When in photoshop, adjust to keep about 3-5% in the highlights and no more than 80-85% in the shadows. If it is a dark photo with very little light areas you can blow out the highlights to open up the midtones somes. Anything in the shadow area over 85% will probalbly close up on the press and you will loose contrast and detail. I have and old version of Photoshop so it may be different, but I like to make my adjustments by going to Image > Adjust > Curves. You can point to an area and see the % value in the dialog box and make adjustments accordingly. Save a copy as a test and play around. The eye dropper doesn’t lie. You can move the highlights, shadows and everything in between.