How can I add spot color in photoshop?

[2mira]

I need to know
how can I apply - (Add) five color (spot color ) to layer in photoshop file

 

[Stephen Marsh]

I need to know
how can I apply - (Add) five color (spot color ) to layer in photoshop file

They are spot channels, independent of layers (unless CC has changed things from CS).

How you get the data into the spot channel will often dictate the quality of the spot. Where possible/practical I would probably use apply image to stamp existing channel data into the alpha/spot channel and then clean up, rather than using selections (unless the selection was perfect).

Make the alpha channel white for no ink, solid for ink, tint value for tints - then change it from an alpha channel to a spot channel.

Unlike other software, Photoshop spot channels overprint by default, so if you wish to knockout/trap - then you will need to create the knockout through the other colour channels (based off the spot channel).

More here:

https://helpx.adobe.com/photoshop/using/printing-spot-colors.html

Spot-Color Separations in Photoshop CS5 � Layers Magazine


Stephen Marsh

 

[DCurry]

Just to add to Stephen's excellent advice, when you create your knockouts you'll also have to account for any trapping that may be needed so you have a slight overlap of PMS and process colors wherever they touch.

 

[pdan]

Wouldn't trapping be applied as in any other scenerio, at the RIP?
If you built a trap into a PS file which was later scaled the trap would be incorrect.

 

[DCurry]

Wouldn't trapping be applied as in any other scenerio, at the RIP?
If you built a trap into a PS file which was later scaled the trap would be incorrect.

In this case, probably no - trapping engines (at least all the ones I've used) don't "look" within an image to trap inside of the image. They look at where an image touches other objects to determine if traps are required.

You do bring up a good point about the trap being scaled - it would be important to make sure this image is at correct size to begin with. I usually make a 1-pixel trap, but you may require larger depending on your needs. Can't do smaller than 1 pixel.

 

[Simon Ivarsson]

Another approach can be to create a grayscale image and colour it later in Illustrator.
But this depends on how the image looks like and how the process colours interact with the spot.

 

[pmkprog]

In this case, probably no - trapping engines (at least all the ones I've used) don't "look" within an image to trap inside of the image. They look at where an image touches other objects to determine if traps are required.

You do bring up a good point about the trap being scaled - it would be important to make sure this image is at correct size to begin with. I usually make a 1-pixel trap, but you may require larger depending on your needs. Can't do smaller than 1 pixel.

I usually shoot for a 2 pixel trap. In most cases, since you are printing digitally, trap is not as much of an issue as it would be on a conventional press. If the file is needed for both types of systems, then it is best to follow the the comment above about setting it up at the exact size and doing a proper trap for your printing requirements.

 

[dpolglaze]

Having essentially left offset years ago for digital, and having been very deep in that end on design through support, I have not seen anything on a digital press that needed trapping. I did a lot of training on Creo and EFI Fiery RIPs with customers and generally just glossed over the trapping they do, but I always stated that trapping could come into play if you had, for example, a 100% Magenta image overlapping a 100% Cyan image. If the color registration was off slightly on the press you might see the dreaded white line.

Happy (digital) Printing!
Dwight

 

[Stephen Marsh]

NOTE: Forgot to add, even though the spot channels are independent of layers, you can create your “knockout/trap” hole losslessly in a layer by filling the spot channel selection/trap with white, you don’t need to permanently knockout the CMYK content with a lossy edit.


Stephen Marsh

 

[DCurry]

In most cases, since you are printing digitally, trap is not as much of an issue as it would be on a conventional press.

I don't see where the OP mentions anything about printing digitally? Did I miss something?