Pre Press

Wednesday, January 3, 2007

Post Xmas

Well Xmas is over (thank god) and so is new years. So now it's time to do some more work. Just need to remember where I was up to...

Sunday, December 3, 2006

Post Test...

Testing my bog, seeing if it's postable!

Saturday, December 2, 2006

Introduction

Hello there,

there's very little to this blog at this point in time, but before Xmas there should be a lot more info in regards to Pre Press. So stay tuned...

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Throughout this blog you will see the word "image". I refer to a image as something that has been taken with a camera or has been scanned. I do not refer to a piece of artwork that has been drawn in a program such as Illustrator or Freehand as an "image". These are illustrations or artwork, not images and work in a completely different manner.

Although Photoshop now includes text editing capabilities as well as the ability to create "artwork" as referred to above, it's strength is still editing images. For this reason I would not recommend Photoshop for anything except image editing.

I have also used Photoshop for the examples in this section simply beacuse it is the industry standard image editing program for most offset print companies.

And Now For Something Completely Different... I'm going to make a quick detour and discuss something that is a little beyond the scope of this section. That something is colour. Colour is a tricky business. Just ask any panelbeater about colour matching. For your interest, colour is all about physics. And the colours you will hear about in the print industry are Cyan, Magenta and Yellow or CMYK.

Now you might have noticed a word missing. That word is key. Key is also known as black. Part of CMYK or Cyan, Magneta, Yellow & Black. But black is not a colour. Just try switching off the lights at night and then try and tell me that there's colour around. That's if you can find your way around in the dark.

For something to be a colour, it must reflect light. Try switching off that light again and look at how much light is being reflected. Not a lot I'll bet which is why everything is black.

So just what does this has to do with Photoshop? Well I'm going to discuss two colour modes that are present in Photoshop - RGB & CMYK. As well as why your offset printed picture of a blue sky doesn't look like the real thing. And let's not forget the "colour" black while we are at it.

RGB or Red, Green and blue comprises what is known as white light. Or sunlight. Simple as that. The reason that sunlight doesn't look red, green or blue is that when all three colours mixed, at their full intensity give the appearance of white light.

Try holding a prism up to the sunlight and watch the new colours that appear. You only have sunlight going in, but all these new colours coming out. So where are the red, green and blue colours, and just where are all these other colours coming from.

Well combine green and blue and you will get cyan. Combine red and green and you get yellow. Combine red and blue and you get magenta. Which leaves only black, which is not a colour anyway because it doesn’t reflect any sunlight.

Notice I used the word combine repeatedly in the last paragraph. So why not use RGB instead of CMYK. The simple answer(s) is paper and simulation. Going back to why does this offset printed picture of a sky not look like the real thing is the result of this. And here is why in a little more detail.

When sunlight hits the earths atmosphere some of the blue light in sunlight is adsorbed by the molecules present. After a period of time this blue light is released again hence giving the sky it’s blue colour.
But paper is not made from the earths atmosphere. It’s made from trees and a tree is just a wee bit different from molecules floating round in the earth’s atmosphere. Hence it has a different “absorbency of light”.
The reason that trees look green (unless they’re dead or dying) is because they absorb most of the blue and red out of sunlight and reflect green. This is due to the material the tree is made from.

The reason a lemon looks yellow is because it absorbs most of the blue out of sunlight and reflects mostly red and green. This gives us yellow. The reason it reflects mostly red and green is because of the material it is composed of.

Paper is not composed of the same material as a lemon, or the earths atmosphere. In fact about the only material that is similar in composition to paper is, um… paper.
This is why we have to simulate RGB. Magenta and Yellow gives us Red, Magenta and Cyan gives us Green, and Cyan and Magenta gives, well umm… Purple. Not blue. Unless you back the Magenta off a lot. Then you’ll get blue. But not a very bright blue. And the reason for this is… (drum roll please), paper! Paper is why we have to simulate colour when we offset print, and simulation is not as good as the real thing. (At least not in this author’s experience).

New

When creating a new image you will first need to select the new option from the file menu. The dialog box that opens will have two options that are particularly important to Pre Press. One is resolution and the other is Color Mode. Make sure you select CMYK and not RGB for your color mode, and 300 dpi as your choice for resolution.

Opening

When opening an image for the first time, the colour mode will be written in the title bar of the enclosing window. This should read CMYK.