Color Separation Part 2

How to color separate an image with complex gradients and intricate coloring.

            When you create a gradient with screen printing you are creating an illusion. Take a look at this transition from aqua to white. By using halftones the eye is fooled into thinking the color is changing.

The dots of ink are packed tighter together where the color is darkest. As the transition to white occurs the spacing between the dots widens. So you are physically laying down more ink where you want the color to have a deeper tone. The further the spacing of dots, the lighter the color will appear to the eye. The color of the ink in your screen is still the same; it is simply passing through the screen differently.

            If you are working with a gradient layer, color separation is pretty straight forward. Here is a tutorial that explains it step by step.

http://theartofapparel.com/index.php/color-separating-complex-gradients-by-heavy-prints/

This post concerns people who are not working with a gradient layer.

Just like in “Color Separation Part I” we will be working with channels and the color range tool.

When working with channels, make sure you have the correct dimensions set before you start editing. You will not be able to effectively change the image’s dimensions later!

Step 1: Start by hiding the layers you do not want to separate.

Step 2: Using the color range tool separate each color.

            Because you are working with gradients, the color range tool will not be as precise as separating spot colors. You will have to play with the fuzziness to choose just how much of the color you want the tool to select. With your first selection choose an area where the color is the most solid. With your second selection choose an area in the gradient when the color has less of its original tone. We will then merge the two layers together. Below you can see just how much of the yellow I take from the yellow to aqua gradient. 

Once you have the color selected, invert the colors Ctrl + I and then click save as channel in the bottom right.

Now, repeat this step with the next part of the gradient. In this case it will be a lighter yellow.

Step 3: You should now have two channels that represent the darker and lighter yellow in the image. Now we will merge the newly created alpha channels.

Image > calculations

Layer merged

Source 1: Merged Alpha

Source 2: Layer 1 Image Alpha 2

Multiply

100% opacity

Ok

We have now created a 3^rd channel Alpha 3

Rename this channel yellow or whatever color you’re working with.

Now repeat steps 2 and 3 for all of the colors/gradients in your image.

Here we see all the newly merged alpha channels selected. This shows 5 colors.

Step 4: However, as you can see, even with all the channels selected we still have patches of white throughout the image. We want the image to be completely pink when we select all of the channels. Use the pencil tool and eraser tool on the individual channels to fine tune this. You must have two channels selected to use the pencil tool on one. Be sure to turn down the opacity so as not to erase too much or create darkened overlap.

(It helps to view the original RGB image with your channels to see where the color is missing)

 

 

 

Also, creating the new aqua channel has left us with unwanted color on the right. No problem, select the channel, and magic wand the unwanted areas with contiguous checked and delete.

Use the dropper tool to make sure you have no instances of white. You shouldn’t be concerned with very light shades as they will become halftones once put through the rip software.

While it may look there is no color with all the channels selected, there may be a light shade. This is eventually what becomes the halftone and what will give you the variance in color.

Shop Page Photoshoot

After a year's work the line is done. Here is a picture from the photoshoot of the tees on their own. Next up is the collection shoot with models...

Vector Art vs. Raster Art

                For the most part, my artwork is done in either of two ways. One, I will draw something by hand and then scan it into a computer to create a finished work. Or two, I will work from existing images such as photographs and art and add and alter them using Photoshop to achieve my vision. When discussing this process with a friend of mine who is a designer, he kept stressing to me the importance of using a vector program like Corel Draw or Illustrator. At the time I was so familiar with working in Photoshop that it was hard for me to even consider transitioning away from it. To save any aspiring artists or screen printers some time. Create your artwork in a vector program! Here’s why:

                 A Raster image (or bitmap image) is based on pixels, lots of small squares put together to form an image. For any classic gaming fans, think NES Mario. 

The problem with raster art is that you cannot accurately re-size your work. Raster programs will simply create more pixels thereby degrading the original quality of you artwork. Think about a small picture that has been blown up that looks blurry and grainy. When re-sized, the quality of the picture has been lost. This is where we get the term pixilation. Vector art, on other hand, does not have this problem. Vector art uses precise lines and endpoints. When you re-size with vector programs your lines and points are sized according to a formula keeping everything proportional. The additional advantage of vector is that your artwork will look much cleaner and precise. http://upload.wikimedia.org/wikipedia/en/a/aa/VectorBitmapExample.svg

                When it comes to screen printing, vector vs. raster can have an enormous impact on your work. Imagine you want to print giant letters (in this example I’ve used Tahoma font 250 size). When you zoom in, you can see the graininess of the font, if you have a good exposure unit this pixilation is going to come out in your prints.

Here’s the same look in illustrator:

In the immortal words of Top Gun, “Ice cold, no mistakes.”

Now before you go running out and thinking vector art is the end all be all, think again. For things such as text and fine lines, www.risewest.com/stickthislogic illustrator is definitely the way to go. However, sometimes you can use a bitmap image and it will make very little difference. Consider this image 

There is so much going on in this image that you don’t really notice it is raster. Even when you zoom in it is hard to notice.

If you look very carefully at some parts of the stem you can see the bitmap, but you are still going to get a nice looking print regardless, www.risewest.com/tree

                The important thing to note here is that you can create powerful artwork in both vector and raster programs. Choosing between the two will often depend on what you want to achieve. Personally, the more I learn about design and printing, the more I tend to gravitate toward illustrator.

                Now, as I said originally, my artwork is created in either of two ways, hand drawn or from existing images. Both methods are very simple to import into Photoshop and work with. Illustrator is another story. Everything that you import into the program must become vector. Consider this, when you scan an image (given you’re using an everyday scanner) you’re creating a raster image. Any photograph you have will also be raster. The majority of what you pull from the web, any jpeg, tiff, jiff, are all raster. This means, unless you are starting from scratch, you will have to learn how to trace with the pen tool. This is a skill that will take countless hours to master but will be worth it once you do.

Mailers

 

Mailers printed. Used a nice aqua that didn't end up getting up used for the fish shirt.

Color Separation Part 1

In this post you will learn how to color separate a basic image using Photoshop.

One thing you need to realize as a screen printer is that pulling a squeegee is only a small portion of the overall process of printing. In fact, the majority of your work should be done in the preparation stage, not the printing stage. The preparation stage begins with artwork. Some common questions you should be asking yourself when planning your artwork are: How many colors am I working with? Is this going to have halftones? Is this a process print? Spot color? Blend? These are all things you must familiarize yourself with.

            A critical step in the printing process is learning how to color separate. Whether you have created an image from scratch or you already have an image from somewhere else, you will have to color separate to print a multi-color job. Let’s take a look at the process:

            Like with anything in screen printing there are several ways of color separating. You can create your artwork on separate layers or channels; you can use a color separating program (usually around $700-$1000), or you can use Photoshop. In this tutorial, I will go over the method I most often use, which is the color range tool in Photoshop. Let’s begin with an image that we want to color separate. We will use Andy Warhol’s famous Campbell's soup print.

1.      Copy the image, create a new file and paste the image onto the art board.

2.      Take note of how many colors your working with here. (I see 5: white, black, red, yellow, grey, though one of these colors will be the background of whatever you are printing on). So, this is a four color job.

3.      Click select > color range

a.       There are two ways to use this tool. You may select sample colors or use the colors Photoshop has already selected.

                                                              i.       If you are working with a complicated image with lots of colors you may want to use sample colors and select the colors yourself. This tool works like the magic wand in that you click on a color in your image and Photoshop will find everywhere that color appears in the image. You can also play with the fuzziness to select more or less of the color (more on this in part 2).

                                                                                       1. Note that in theory, using the select colors will be the most accurate way of reproducing an image. However, there are nine selected colors, do you have a nine color press? 
                              ii.   The other option is to use the color Photoshop already has in place

4.      Using the colors Photoshop has in place begin with reds and click okay. Photoshop has now selected all the red that appear in the image. Click control, shift, I or select inverse. Go to your channels and click save selection as new channel.

5.      Repeat this process for the Shadows (blacks)

6.      The grey presents a bit of a problem. Click halftones and you’ll find that Photoshop is picking up too much grey (note how it picks up grey in the red lettering of “tomato”. So, for the grey you can just use sample colors.

a.       Click sample colors, move the dropper over any grey in the image and click. You can now adjust the fuzziness to get the grey in the image that you actually want to print.

7.      Similarly, if you try to use the yellows it will not find a good enough sample. That’s okay just use the sample colors again like you did with grey.

8.      You now have 4 channels, if you click the eyeball for them all you should get a solid pink image like this:

  

9.      That’s it, you’re done. However, if you look very carefully, you may notice that the color range tool wasn’t perfect in selecting the colors. That is because the image used was not perfect. You will get best results if you use a high resolution image. If you are ever taking on a job for someone with an existing logo or image make sure to get a high resolution image before you begin to color separate.

In part 2 of this tutorial I will go over color separating an image with complex gradients.

Start

Hello,

     I am the founder of Rise West, a clothing company based in Los Angeles. I started the company in August of 2010. Since then, I have been working away learning about business, graphic design, website design, and screen printing, among many other things.

     Prior to the formation of Rise West, I attended the University of California Davis. In my first year, I took a screen printing class. I had the idea of my own t-shirt line in my head for years and figured screen printing could take my ideas from concept to reality. I have continued to print for about four years now. Unfortunately, a lot of the things I learned in the class were geared more toward hobbyists, and less toward a professional business. Additionally, at the time, I new very little about graphic design and next to nothing about website design.

     So, after returning home from college, I went about learning the right way to screen print. I began putting together a collection of designs and began studying website development, all while trying to keep my budget as low as possible. Along the way, I have made countless mistakes while gathering a few bits knowledge.

     With this blog, I hope to be able to put together a collection of thoughts on fashion, design, screen printing, and starting a business with hopes that I may someday help or inspire someone in a similar position.

    After spending far too much time pondering a title for this blog I have settled on, Ink Thoughts, for now...