Expert: Glen Demers - 7/27/2009

Question
QUESTION: I have a JPG file with a logo consisting of four spot (flat?) colors (if white counts as a color).  I need to be able to do a color separation for screen printing. I think I need to put each color into its own layer but I have no idea ow to do that. My S/W is Adobe CS4.  Can you tell me how to do that - I have virtually no familiarity with Photoshop (or any of the CS4 programs).  Thank you.

Don ()

ANSWER: Hi Don,

Open the a copy of your image and go to Image>Mode>Multichannel. This will allow you to work with the channels. In the channel palette, double click on the name of the channel to rename it, double click in the swatch and you can redefine the color for that channel. With one channel selected erase the portion of the image of the 3 colors you don't want, leaving only the color you want for that channel. White does not count as a color if it's just the background, you may need a white separation if it's part of the image and screen printing on colored media.
Once the channel contains only image parts of one color go to Image>Adjustments>Levels. Slide the black triangle to the right until the image darkens to 100% and slide the open triangle to the left to eliminate any background artifacts.
After doing this to each channel you can select them all and see how it looks in all colors.

Hope this helps,
Glen Demers
Adobe Certified Expert, Photoshop 7
Prepress Technician, Best Printing Online
www.bestprintingonline.com

For more Photoshop tips please visit our help pages here: http://www.bestprintingonline.com/photoshop.htm

---------- FOLLOW-UP ----------

QUESTION: Thanks for a great answer... regrettably, I don't fully understand it. I did go to channels where I discovered that Photoshop seems to have automatically separated the image into CMYK channels.  However, when I look at each channel, there seems to be an awful lot of overlap - I suppose that is normal to have yellow & red together to produce a less than red effect.  Anyway, I would imagine that the separation provided by default (CYMK) should work for me... how would I use those to produce the desired output format for my T-Shirt lady?  I know she uses Corel draw so I would like to out a file she could use.

Finally... In addition to the logo, I will need to add some text - is that something I should do prior to color separation?  How would I add text in Photoshop? I am very familiar with MS Publisher but not the Adobe products.

Oh, I have attached my image so you can see what I am talking about.

ANSWER: Hi Don,

Photoshop automatically separates the image into it's native color space. in this case CMYK.
It may be easier to give your T-shirt lady the jpg and let her use Corel Draws tracing features to recreate the logo rather than do it in Photoshop.
I'm not even sure if you could import a multi channel photoshop file into Corel,

Glen

---------- FOLLOW-UP ----------

QUESTION: I didn't ask my question correctly.  BTW - she said she can't use the JPG.

Anyway, specifically, how can I get Photoshop to print PDF files for each of the CMYK channels?

No more follow ups... I don't want to abuse your generosity.

Answer
Hi Don,

You'll have to make 4 copies of your jpg file and I would suggest naming them jpg-C, jpg-M etc.
Open each in Photoshop and in the Channel palette select the three channels you don't want and delete them. You may have to delete them one at a time.
When you get to one channel, Photoshop by default displays it in black and white, so it's important that the name matches the channel you're left with. Photoshop will display the channel color in parenthesis at the top of the image window.
Once the image is down to one channel go to Image>Mode and change from multichannel to grayscale. You can then save them as pdf files.

Hope this helps,
Follow up with new questions if necessary, happy to help.
Glen