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Printing Basics
This page is to provide helpful tips and to aid you in developing a proper print file. For detailed instructions, please choose the appropriate topic from the links below.

Sections: Color,
Resolution, Format, Scanning, Digital Cameras, Calculating Resolution, Web Images and Proofing/Color Viewing
 

Color Basics
To understand how colors relate to printing, you should understand the difference between projected and reflective color.

Projected Color
Scanners and digital cameras create images using combinations of three colors: Red, Green and Blue (called “RGB”). These are the colors that computers and TVs use to display images on your screen. This is color produced by light shining out or projected color. The problem is there is no way to do “real ink on paper” printing from a file that has colors created in RGB. They must be converted to CMYK. You can convert your RGB images using an image-editing application such as Photoshop, Corel PhotoPaint or another pixel-based editing application.

Reflective Color
When an image is printed on paper a color is produced by light hitting the paper and reflecting that color (spectrum).

Reflective Color

In the printing industry four colors are used to produce all the colors in the rainbow: Cyan (blue), Magenta (red), Yellow and Black (K) (called “CMYK”). You must start with a CMYK image or convert your RGB image to CMYK in order to produce a printed product. You can convert your RGB images to CMYK using an image-editing application such as Photoshop, Corel PhotoPaint or another pixel-based editing application.

RGB Color Model

Additive color model for computer displays uses light to display color. Colors result from transmitted light: Red+Green+Blue=White

RGB Color Model

CMYK Color Model

Subtractive color model for printed materialuses ink to display color. Colors result from reflected light:
Cyan+Magenta+Yellow=Black

RGB Color Model

RGB to CMYK Color Conversion
Files that have been created in RGB will need to be converted to CMYK because it is not possible to produce ink on paper printing from an RGB image. Files that were created in RGB and converted to CMYK will have a color shift. On some designs it is not very noticeable. On others the shift will stand out. During a color conversion all colors change from being built from 3 colors to being built from 4 colors. The colors are also changed from projected light to reflective light. Notice on the RGB color chart above that when all 3 colors come together the color white is produced. When all colors come together on the CMYK color chart the color black is produced. We prefer that our customers convert their RGB images to CMYK, therefore they have control over the final outcome.

Black Builds
Use caution when you have a solid area that is Black. Four-color process (CMYK) should be used to create a deep, dark, black, however if the total percentage of all four colors is greater than 340% your document will not print properly. Ink will saturate the stock and you will not be pleased with the final product. The only exception to this rule is text, you should use 100% black ink. We have developed settings that we know work well on our presses. Please use these settings when designing your document.

The optimum settings for Black are:

  • 100% Black
  • 75% Cyan
  • 70% Magenta
  • 40% Yellow

Black Text / Fonts:

When creating black type please give it the following CMYK break down:

  • 100% Black
  • 0% Cyan
  • 0% Magenta
  • 0% Yellow

Resolution
All images used for printing should be a minimum of 300 DPI at the size used for layout.

PPI vs DPI

The first important point to understand about resolution is the difference between PPI (pixels per inch) and DPI (dots per inch). Many software programs and scanner interfaces use these two terms interchangeably but that's not exactly accurate. As a general rule, the term PPI should be used when referring to image resolution, and the term DPI should be used when referring to printing resolution. How can you remember this? Monitors display pixels, and printers produce dots. Printed images are composed of dots. Image resolution is simply the number of dots in a 1-inch grid.

There are two aspects to every image - its dimension (width and height in inches) and its resolution (the number of dots per inch). These two factors alone determine the total number of dots in an image. For example, a 2-inch by 3-inch image with a resolution of 300 dots per inch contains (2 x 300) x (3 x 300) or 540,000 dots.

The DPI of an image is determined when the image is captured. Let’s say you scan an image at 200 DPI into PhotoShop. Once in PhotoShop you increase it to 300 DPI. The image will print as if it were a 200 DPI image. All you have done is used 300 dots per inch to produce a 200 dots per inch image. You will need to recapture your image at 300 DPI or scale it accordingly.

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Format
Scanned images should be saved in a TIFF (.tif) or EPS (.eps) format to ensure the best color and sharpness possible. File formats such as GIF or JPG compress the picture and can cause it to look blurry and off-color when printed.


Scanning
When scanning images to be printed you should follow a few simple rules. Scan your image at the final size you will need for your page layout. Scan your image at a minimum of 300 DPI, 400 DPI if your image has text.


Digital Cameras
Images from digital cameras are acceptable, as long as the pixel resolution is adequate. For example, if your camera has a typical image of 1280 x 960 pixels at 72 DPI, you get about 17” x 13” of photograph at 72 DPI. This is comparable to a 4” x 3” –300 DPI image. 4” x 3” would be the maximum size that the image could appear in your printing layout.


Calculating Resolution
Calculate the resolution of your digital image and the maximum size you can go to retain a 300 DPI resolution as follows:

  • Determine the pixel dimensions from your digital camera
  • Divide those numbers by 300 (divide by 400 if the image contains text).

For example, an image without any text has a pixel dimension of 900 x 1200. When divided by 300, the maximum size of the image in your layout comes out to 3” x 4.” If you make the image any larger, it will not look sharp.


Web Images
You may be tempted to use a photo that you have lifted off of a favorite web site in your printing layout. Website images have a low resolution (72 DPI) and look terrible when printed on an offset press. Also, web images are in GIF or JPG format, so these images are sure to look disappointing in your final product. Check to make sure all images are at least 300 DPI and are legally available for use.


Proofing/Color Viewing
What you see is NOT what you get! Computer monitors display in RGB (Red, Green, Blue), while printed materials use process colors - CMYK (Cyan, Magenta, Yellow, Black). This means that your final printed product will look sharp and crisp, but the colors will look slightly DIFFERENT from those you see on your monitor. If matching colors is absolutely critical, be sure to request an Epson hard copy proof. It is important to convert all your images to CMYK prior to submission.

 

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