Light vs. pigment: What’s the catch?
In our previous article on colour perception, we discussed how we cannot see colours without light. And it is precisely on light that the RGB system is based. This system utilises what is known as additive colour mixing. Imagine it as three coloured spotlights – Red, Green and Blue. When you mix these three beams at full power, you get white light. When you switch them all off, you have darkness – in other words, black (as with a switched-off monitor). RGB is tailor-made for the digital world: for the web, mobiles and projectors##
But how do you print a colour when the bag isn’t glowing?
Whilst your mobile ‘emits’ colours directly into your eyes, a paper bag merely reflects them passively. That’s why, in printing, we use the opposite system: subtractive CMYK colour mixing.
Here, we’re no longer mixing light, but coloured pigments
:- Cyan (cyan)
- Magenta (magenta)
- Yellow (yellow)
- Key (black, or ‘key’)
When we apply the colours C, M and Y to a white bag, the result is a dark shade. However, as mixing these three colours will never produce a true, deep black, we must add the ‘K’ component. This gives the print depth and contrast.
Why did the colour ‘glow’ more on the screen than on the bag?
This is the most common stumbling block. The RGB system has a much wider colour gamut than CMYK. Put simply: there are shades (e.g. neon green or bright blue) that your screen can ‘light up’, but no colour in the world can accurately replicate them on a bag or on paper.
When converting from RGB to CMYK, colours must be ‘rearranged’ into a smaller colour space, which can lead to a change in shade. Therefore, you cannot compare the colour displayed on a monitor with the colour printed on the bag.
How to achieve the exact shade?
If you want to keep colours under control right from the design stage, it is best to work directly in the CMYK colour profile
.- Print data: Save your files in formats that preserve colour profiles (PDF, TIFF).
- Logo manual: If you have defined ‘spot colours’ for your logo (e.g. from the Pantone colour guide), please be sure to let us know. We’ll cover spot colours in a future article, but bear in mind that they are the key to absolute precision.
Curves vs. pixels: Why does the format matter?
Now that we’ve clarified the issue of colours, we need to look at the ‘format’ in which you’re sending us the data. You often ask us why we want a logo in curves (vectors) and why an image downloaded from the web or a photo taken on a mobile phone isn’t good enough.
What is a raster? (The world of pixels)
Raster graphics (e.g. JPG, PNG, TIFF formats) consist of tiny coloured dots – pixels. Think of it as a mosaic. As long as the image is small, it looks great. But as soon as we start enlarging it to fit onto a large shopping bag, the pixels start to ‘stretch’. The result is a blurry, ‘jagged’ or out-of-focus print, which simply doesn’t look professional on the bag.
What are vectors? (The world of maths)
Vector graphics (e.g. PDF, AI, EPS formats) do not work with points, but with geometric shapes and mathematical equations. For you, this means one huge advantage: you can enlarge (or reduce) a vector design infinitely, and its edges will always remain perfectly sharp.
Why do we need vectors for printing on bags? Most of our technologies, such as screen printing or flexo printing, require absolutely precise and sharp edges on the design when producing printing plates (stencils or plates).
- With vectors, the machine knows exactly where the ink begins and ends.
- With raster images, the edges are blurred (a process known as anti-aliasing), which the printing press cannot interpret correctly. The result would be a ‘smudged’ print with unclear contours.
So, if you want your logo on the bag to look razor-sharp, look for files on your computer with the extensions .ai, .eps or .pdf (in print quality). Your brand deserves to be sharp.
Leave it to us.
Are you getting lost in colour spaces and don’t know your way around computer files? Is graphic design a ‘complete mystery’ to you? At Easybag, we have a team of experts who will guide you through the whole process.
We’ll create previews for you, check the data and recommend the ideal solution. Whether you want a luxurious premium bag or are looking for the cheapest option for a machine-made bag with high-quality printing, we’ll make sure the result is worth it.
