Digital Print Workshop 1

Digital colour modes:

• RGB-display of colour on screen
• CMYK-preparing for print

Where the colours overlap= new colours are created.

Process:

Cyan-yellow-magenta-black (key colour, gives us true shadows and depth of tone in areas where needed)

When we screen print we dont necessarily use the CMYK method; we just get the colour and use it.

Two different ways to apply colour in commercial print process:

• CMYK- processed colour
• SPOT inks/colour- a pot of ink that is the colour that you're going to print. 

Why are spot colours used?

• They can be cheaper e.g. only two inks as opposed to four
• Branding e.g. logos
• Allow the accurate reproduction of colour:pantone colour reference- unique number
• They allow for metallic/flourescent colours to be printed

Preparing for screen printing on Photoshop

Getting the Positives for screen printing

• Selecting areas using magic wand/select similar
• Colour range: select - colour range - 
• What is previewed WHITE is what will be selected
• Selection preview: white matt
• Put it onto a new layer
• Layer-new-layer via copy (cmdJ)

How do we get the proper positive? It has to be black; so the orange has  to change to black.






Quick way to do this with a transparent background:

• lock transparent pixels
• Edit-fill-black 
• Do this with black as well, just to make sure it is 100% black

Printing smaller than A3

•  Always check the image is 300 pixels per inch
•  Image - mode - CMYK
•  File - save as PS or TIFF file, NOT JPGS
•  Channels: store information about colour in the image

E.g. Cyan- darker where there is more cyan ink, lighter where there is less

 

Channels are used to create the positives to print. 

Using Illustrator to separate inks and select our positives: 

Print- output- mode - composite- separations

 

 How can we print different amounts of an ink?

• When we create our positives we have to create half tone screens.
• Half tones are the way we can print different tints of one colour in one ink. 
• Frequency and angles are to do with half tone screens; the lazer printer will create these dots during the printing process
• Frequency = number of dots 
• Angle = how much the grids of dots are rotated so they don't clash when printing 
• Commercial printing: 100-250 lines per inch
• Screen printing: much coarser half tone scren due to the threads on the screen; 50/65 lines per inch
• Dots can also be used for aesthetic effect
• Just two inks? Just use the top two selections.

The angles for screen printing are: 15,75,105,155

The dots are at 40 in this instance so they are visible.

How do we know which is which?

Marks and bleed option- page information 

Printing Larger than A3

Everything has to be done in Photoshop

• Create 1 image per colour channel
• Split channels: photoshop then creates one image per channel
• We need to think about how we are going to do half tones; the printers cannot do this so we have to apply half tone screens to each image.
• Image - mode - bitmap (only if image is greyscale) 
• Bitmap: pixels can only be black or white

 

 

As long as each screen has a different angle it is ok. The bitmap has to be increased to increase quality. 

Do this to each of the positives, then go and print them.

Lazer printer: use illustrator
Inkjet printer: use photoshop