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Pre-Separate Complex Graphics with Index Tables

(February 2010) posted on Mon Jan 25, 2010

Trimingham explains how to use index dots to simplify the process of separating highly detailed garment designs.

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By Thomas Trimingham

I knew from experience that an index dot would probably look too grainy on the second, more colorful, tiger for what the press could handle at a 190-dpi dot. Going with a smaller dot would likely cause the ink layer to be too thin and make the colors less bright. The answer for this file was a traditional-dot separation set. The index-separation method could save time on these separations, and I could then use the file as a basis for creating my traditional positives. I used the following steps to create an index guide for the colorful tiger:

1. I started with the same process I used for the other file, but I didn’t need to isolate the background because it was designed with most of the tiger’s colors and looks.
2. I checked the file’s size and resolution to make sure it was original size and at a resolution of 300 dpi to prevent concerns about the dots being too small.
3. I duplicated the file (never forget to do this!) and then created an index table using the bright colors in the image. I made sure to use a lot of blends between the colors, which I did by clicking on one square in the table, dragging across a couple of squares, and then putting in a first and last color for the blend. This allowed me to replicate the file quickly and still have an accurate reference.
4. Once I had a good index version (this required an undo step or two), I then copied and pasted the file as a layer again. This time, however, I used the colors that I created as defined selections with the Color Range tool. Modifying the fuzziness enabled me to quickly select and save a complicated set of overlapping separations for recreating this multicolor tiger in less than 30 minutes (Figure 7). The gray values in the color range selections were curved out or converted to traditional halftones in the final positives.

This method worked well with the boldly colored tiger because the colors were defined. Had the colors been very similar, with a lot of gray or brown tones, such an approach wouldn’t be appropriate. The image’s great detail and defined colors worked with the process, and I saved a lot of time in separating. As you can see, index-table pre-separating can simplify even the most complex garment designs, regardless of which type of dot you intend to print on press.


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