Photopolymer Plate Image Prep (LETTERPRESS)

The photopolymer plate needs to be printed with the blackest blacks possible.

Our transparencies will ultimately be Right-Reading Emulsion Side Up Negatives

Here is how you do it:

Note: Double click any image to enlarge it!

1/ Choosing and sizing your image

The images that work best are ones that:

• have more contrast. An image with lots of greys and middle values won't turn up great. You can also add contrast in Photoshop.
• You can work with a color image, but you will eventually have to turn it into a B & W image like with all other transparency printing.
• Like with anything, the better resolution the image is, the better it will turn out. However, you can get creative with dot patterns etc. if you want to use a lower-res image.

I have chosen this photo, Untitled, by Carrie Mae Weems to work with.

Make your image the right size and resolution by goig to Top Menu > Image > Image size. Make it as big as I want it to be when printed out (see Paper Store Prices or ask your professor what the max size of your transparency can be; I am using 8.5 x 11 here) and the output I want it to be for the final resolution (see the Bitmapping section below for info about resolution)

2/Color correction

1. Open your image in Photoshop.
2. Go to Top Menu > File > Save As (as we are doing destructive image editing) and save as a new image.
3. Add any adjustment layers you want at this time (eg. contrast, etc.) by going to Top Menu > Layer > New Adjustment Layer
4. Make sure you add at least a B+W Adjustment Layer to make your image black and white:
   1. Top Menu> Layer > New Adjustment Layer > Black & White
      
      1. Set the "Mode" to normal and opacity 100%.
         
      1. A box with some color sliders will come up. You can play around with these until your image looks good to you. Essentially, you are choosing how light and how dark Photoshop sees certain colors.

   2. When you are happy with your colors, go Top Menu > Layer > Flatten.

2.1 /Curves + Levels (optional but highly recommended)

A/ Threshold

We want to make sure the lightest spot is pure white, and the darkest spot is pure black.

To do this, we are going to add a Curves Layer, and a Threshold layer by going to our Layers Window (Top Menu > Windows > Layers), and then clicking the Adjustment Layer icon  from the bottom of the Layers menu.

Pick Curves, and then click on the  again and pick Threshold. The order of your layers should be: Bottom-Photo / Middle-Curves / Top-Threshold

Darkest point

Now we are going to use the Threshold menu to find the darkest point of the image.

This is the threshold menu. If you don't see it, select the Threshold Layer in your Layer Menu and then to go Top Menu > Window > Properties.

Slide the slider all the way to the left (towards black) until you have a tiny bit of visual information left, (let's say about 1% of your photo/image. You are basically filtering out everything except the dark colors.

Your image will look something like this:

Now, select the curves layer in the Layer window. In the curves properties, you will select the black point eyedropper tool (circled in peach below):

Use the eyedropper to click on a dark spot on your image. I clicked on the woman's hair. Then, slide the left/black curves slider (circled in purple) all the way to the left. You will maybe notice that more parts of the image show up. Here is a quick video:

Lightest Point

Now we are going to do the same thing but for the whites.

Go back to the Threshold properties and now slide it as far right as you can while still seeing some parts of the photo (let's say about 1% of your photo). Now you will have something that looks like this:

Now, select the Curves layer in the Layer window. In the curves properties, you will select the white point eyedropper tool (circled in blue below):

Use the eyedropper to click on a light spot on your image. I clicked on the ceiling light. Then, slide the right/white curves slider (circled in green) all the way to the right.

Sometimes, you won't see much of a change. That's ok! It means you had a lot of contrast to begin with.

You can play around with the midtones on the curve slider, too, now if you would like to.

B/ Check values (optional, but helpful!)

Now go to Top Menu > Windows > Info.

Use the dropper to go to the light and dark parks of your image. Hopefully, the whitest white is 0% for all CMYK colors. Rarely will your black be completely black, but we are looking for around 90% K value.

White:

Dark/black:

C/ Flatten

Now you can delete your Threshold Layer (but keep the curves layer!)

Then go Top Menu > Layer > Flatten Image.

3/Invert

Now we must invert our photo. Always do this last, but BEFORE you bitmap.

Let's go to our Layers menu, and then press the Adjustment icon

Now click Invert, and then once again Flatten your image.

4/ Make your image grayscale

1. This is different than making your image black + white. You are now telling the computer to only see black whites, and greys.

2. From the top file menu, press Image > Mode > Grayscale

   If it asks to "Discard Layers," press "Flatten"

5/ Make your image a bitmap

There are several ways to make your image a bitmap. Note that the way they appear on your screen is different than how they will appear printed out. Zoom in to see details of the dot pattern.

Option A: Halftone

Halftone has the classic newspaper/comic book style dots.

To halftone your image:

1. From the top file menu, press Image > Mode > bitmap

   1. The resolution doesn't matter a lot; the frequency of dots on the next screen does more. Just remember higher resolution = bigger dots. Staying around 200dpi is a good strating point.
   2. For "Method," pick "Halftone Screen"
      
      
      
2. In the next dialog box, set the frequency between 20 and 65 lines per inch. You can play with this to see your output dot size. You can also play with the angle and the shape. If you don't like it, just press CMD + Z (CTRL + Z on PC) to undo.'
   
   
3. Press ok and you're done:
   

Option B: Diffusion Dither

Diffusion dither randomly pixelates your image and can often (but not always) give you a clearer, more "true" photo.

1. From the top file menu, press Image > Mode > bitmap.

2. In the box that pops up, keep your resolution the same (because remember, we set this in step one.) With the plate maker, we can go up to about 250 dpi. Less is fine too for a more grainy look. I am going with 200dpi.
   

3. Press OK and you are done.
   
   
4. Final output looks like this:
   

6/ Save + Upload your image

1. Press File > Save As
2. Name your file and save as Photoshop (PSD) on the Format menu.
3. To print your transparency: Ask your teacher where they want you to save your final file. If unsure, save on your USB drive, or to the Short-Term Storage Box Folder.
   1. Personal Backup: Files will automatically delete from the school computer when you are logged out. If you are on a shared computer, make sure to save a backup for yourself by: emailing to yourself, uploading to a cloud service, putting on a personal USB.

Print!

You can either have your transparency printed by your professor or TA in the print office on the Epson 3880 (there are size limits on what we can do). See Paper Store Prices for current price and size limitations.

Or, you can get it printed at Graphic Arts (cash/cheque only!)

Staff: How to print transparencies on the Epson 3880.

Click here for instructions!