How can I avoid seeing exceptional color stains

Question

Using CS5

Hello I edit a file in PSD and save it as PDF (for laser cutting) In this file there are only three colors. Who receives the file, says he sees more colors alone of the three colors I created. I will note that the exceptional color stains are very small sizes and are color transitions. How can I avoid seeing other colors, so that only the three original colors.

By the way the meantime I tried some changes saving the file as: In COMPATIBILY changed in the list of ACROBAT 8. In COMPRESSION: In OPTIONS changed to DO NOT DOWNSAMPLE COMPRESSION to NONE (or ZIP) In addition I have also sent RGB and CMYK. I even made FLATTEN before saving to PDF.

Thank you

Answer 1

CMYK, or process, builds will almost always have some color bleed through simply due to how process colors work.

You could disregard the visual color and use 100% Cyan, 100% Yellow, and 100% Magenta. After all three colors are three colors and on screen it makes little difference as to what those colors look like. When working this way, it's the ink on the press that determines color, not the image you see on screen. This would give you just three colors.

To do this you simply delete data from the channels you do not want that color on. For example, if setting up the Cyan, you would select the Yellow Channel and erase (paint white) anything which is not meant to be yellow. Then do the same for the Magenta Channel and Black Channel - erase anything which is not intended to print Magenta/Black. Repeat for the other colors.

This method works but the actual image on screen will not appear in the colors. You have to learn to trust the construction, not the colors on screen.

If you are dead set on seeing the image in the actual colors they will print in, you'll need to use Spot Color Channels. Spot color channels allow you to select a spot color (Pantone, Toyo, etc) and use a channel to display that color information.

Configuring spot channels can sometimes be a daunting task for someone unfamiliar with print production and color separations in general. The difficulty arises for many in the fact that you can't utilize layers within Photoshop when working this way. Everything has to be done on the Channels.

Here is a basic tutorial, from Layers Magazine, on configuring spot color channels.

Essentially you create a new channel, select what color that channel represents, then paint black on that channel. Black is where the ink will be printed. You then repeat the process for each separate color you want to use. Then save as .psd, .pdf, or .dcs to retain the color information.

Of note: If the entire purpose is to create artwork for laser cutting, Photoshop is really the wrong application to use. You should be using Illustrator or Corel Draw, or a vector application. For laser cutting you want strong, crisp, straight, lines. That's not what Photoshop excels at.

Answer 2

Laser cutting is essentially line art with only one color.

Your art should be supplied as one color (100% black) for each color.

You would specify the color of the material being cut: it is not a color printed onto the item.

To work with this in Photoshop, you might isolate color 1(dark blue) to the Red channel, color 2 (light blue) to the blue channel and color 3 (red) to the green channel. You can then get some idea of the layout together (obviously in false color), and then create three pdfs each with only one of the channels (delete the other two channels and convert to greyscale, then export to PDF, then REVERT). Label each pdf with the desired final color.

An alternative to using the channels, is to make a layer for each desired color, use "color overlay" layer effect to differentiate them and then export them individually as in the above paragraph (replace the word "channel" with "layer" during the export phase)

Answer 3

The only image format in PSD that would make a truly 2 color file is BMP. Every pixel is either white, or it's black.

In pretty much every other file format, for most files, you're going to end up with many colors, as, after all, PhotoShop is a tool for raster images which tend to be continuous tone images.

What you are seeing in the example file is a zoomed in part of the image that has anti-aliasing. Anti-aliasing is when the edges of objects in your file are slightly 'blurred' by having the pixels along the edge color blend. When zoomed out this gives you the appearance of a smooth edge, even though it really consists of all sorts of individual pixels of different colors.

If the vendor can't handle that file, then they shouldn't have asked for a PSD file. In fact, they should have asked for a vector file--or they should have the knowledge to deal with the PSD you sent.