Designing Plates

Hi there — I am wondering what is the best method for designing images for plates. I see lots of graphics with lines that are used to define color (i.e. more lines closer together to get greater ink deposit). Is there a filter in PhotoShop or something that I can use to create this effect, or is this only possible with artistic, hand drawn art?

Or — do you have any tips for someone who is a bit rusty with PhotoShop?

image: birds.jpg

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there’s some filters in photoshop that may accomplish that.
Sketch/ graphic pen or halftone pattern. Also Pixelate/ mezzotint. You’ll have to check with who’s making your plates to make sure you don’t create dots or lines to thin or small for them to etch. You’ll also want to be sure to convert the image to a bitmap so you nothing but black or white in the image and no grays.

On that point, Lammy (or anyone else who knows) is there a standard resolution / dpi required on files supplied for making plates, or does it vary between plate makers and between the kinds of plates being made?

typically photo resolutions are based on the line screen the halftones will be made at. IE a 150 line screen job will need images at 300 dpi. Since your most likely not making screens you may want to use more resolution for your images. Typically you get good results using a multiple of the final output resolution. IE if the imagesetter is making film at 2400 dpi you can make your images at 300dpi, 600dpi or 1200dpi. The higher the resolution the better fine detail you will keep on the films up to a point. IE if your final resolution is 3600, then files at 1800dpi may not appear any different than files at 1200dpi. Essentially there comes a point at which the human eye cannot see the difference in the size of the images spots.
Also since there films are then being used to etch either a piece of magnesium or polyester, those materials may not show any difference between say 600dpi and 1200dpi.

I’ve only ever sent out for magnesium plates made from vector files imaged at 2400 dpi. Mostly just text and line art.

I use mostly Illustrator. Think lines, thin lines, lines close together and far apart will give you depth and an illusion of colour range. Illustrator is best for it is vector art and the above illustration could very easily be created or drawn in illustrator without the worry about resolution.

I just found something very useful that will work well with this.

In Photoshop when turning an image into Bitmap Color mode one of the options in the “Method” pop up is “Halftone”. From there you can set your line screen and they type of “dots” it uses. One of the options there is line which can give some interesting results.

The only downside to this method is the need to work at resolution of the output device, which will make for some hefty files.