Hi!
Have you tried using a Channel to create your spot UV?
First, make sure you are using an RGB image, and then open up the Channels Panel. If you look at all three channels, you will notice that the Red Channel has the most contrast. Duplicate the Red Channel, and then open up Curves and adjust the image so that what is gray turns black. Click Ok and you now have an image that will allow you to put down a UV coat just on the light areas.
Click on the composite image at the top of the Channels panel. Go back to the Layers Panel and add a new Layer. From the Select Menu, choose Load Selection, and choose the "Red Copy" alpha Channel you just created, click the checkbox that says Invert, and hit Ok. You now have a selection of everything you want to turn black--so fill with Black. I hit return+delete and select Black from the Dropdown menu.
Now you have an image that you can paint out whatevery you don't want to be UV coated, and then save it as the file to give to the printer to use for the UV. Rember whatever is white will have the UV coat and whatever is black will stay uncoated.
Let us know if you have any questions!
Michelle
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