A printing press does not uses thousands of shades of ink. It actually uses a single color of ink that is printed in tiny dots, these halftone dots vary in diameter to simulate different shades. These dots are so small that the individual dot are not apparent unless you have very good eyesight.
Terms and their importance:
DPI- This stands for dots per inch. This is used to describe the resolution of an imaging device such as a printer, imagesetter, or a platesetter. The higher the resolution (DPI) the better quality the picture is. It is very important to know DPI because you need to know what type of resolution your printer can output. You can't create something with a DPI of 2400 when your printer can only reach between 600-1200 DPI.
LPI(Lines per inch)- This measures the rows of dots and is used to describe the frequency of halftone dots. Screen ruling is usually measured in LPI. This is important because you need to know what screen rulings you can use on different substrates. Newspapers use a lower DPI because the coarse substrate used for newspapers won't support fine line screens.
PPI(pixels per inch) This describes the image resolution. In this class all of our files need to be saved as 300ppi.
CMYK vs RGB
CMYK stands for Cyan-Magenta-Yellow-Black, these are process colors that are transparent and when they are combined on paper they produce different colors.
RGB(Red-green-blue) is displayed on our computer monitors. This is the color gamut that the monitor can reach.
Both of these color gamuts can reach ranges of colors the other can't. That's why its important to have a swatchbook of color on hand so you can type in the code of the color you want and that will be what you get in your prints. What you see on your monitor might not be what you get after you print.
Spot colors:
Spot colors are necessary when you need printed inks that are not in the range of CMYK. Using CMYK inks would make your job a four color job meaning it uses the four ink plates to create your whole image. If you have a spot color, it is made for your job. If you can eliminate your CMYK color to just a one plate spot color. This would decrease your four color job to a one color. However if you add spot color to your already four color CMYK job then it can printing costs.
Registration is the alignment of printed inks. Natural variation in colors can camouflage small amounts of misregistration. On large presses the paper has registration marks that are scanned to keep them aligned when they are moving at a fast pace. Printing in shades of a single color can diminish misregistration.
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| bad registration in two color logo |
I like how the textbook describes the use of Rich Black. Solid black areas usually need to be beefed up or they will appear anemic. Print service providers vary on the definition of rich black but according to the author of Real World Print Production the color consists of C-60 M-40 Y-40 K-100. this is also said to add a neutral color balance to avoid a color cast to rich black areas.
Controlling your Environment when it comes to color management:
Minimize lighting interference. Avoid glares on your computer screen and try to have consistent lighting in your room. Surround yourself in neutral colors.
Subdue that psychedelic monitor background. Use a gray desktop or grayscale image as a background.
Calibrate and profile your monitor.
Treat your desktop printer kindly. Buying recommended name brand ink is a lot better for your printing job and you will get what you pay for.
Invoke Printer profiles.
All images are from Real World Print Production by Claudia McCue.
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