Raster vs Vector Art
Raster
A raster file is an image composed of a finite set of dots called pixels. The word “pixel” comes from combining the “pix” in picture, and the “el” in element. So, essentially a pixel is a picture element.
Every pixel is square in shape and assigned a specific color. If you imagine a multi-colored chess board as being a close-up of a raster image, it can help paint a mental picture of what I’m describing.
Unlike a vector file, a raster file is dependent on the resolution of the file. The number of pixels that fit into a square inch determines the resolution. A 72 ppi (pixels per inch) file means that the image is only composed of 72 pixels in that square inch. A 300 ppi file means there are 300.
Smaller pixels means the image looks better on a computer monitor, phone or even your television.
What you need is to strike a balance based on your intention with the file.
More pixels = better quality.
Fewer pixels = faster download speed.
For files, the pixels per inch is the resolution of the actual file. Dots per inch, or dpi, refers to the capabilities of the printer used. Dpi is the density of the inkjet dot placement. It aligns with the pixels per square inch rule too, so the higher the number the better print quality.
For resolution, especially for production, you always want a bigger number.
Low Resolution = Bad
A low-resolution image is usually what someone “borrows” off of some website somewhere to use as the basis for their artwork.
An easy way to tell if the image will have reproduction challenges is to just look at the edges. If they are “stair-stepped” or look jagged, it’s going to be tough to get that to reproduce cleanly without a lot of work to that file. Just look at the image we chose for this article. See the choppy look at the background image has? That’s the indication of poor resolution.
When you ask for a higher resolution file and your customer just changes the resolution from 72 to 300 and sends it back to you, that isn’t solving the problem. When that file was transformed, the software program had to basically guess how it should look and filled in areas with pixels to make the change.
What’s added might not be a good solution.
While you can always make resolution lower, bumping things up to a higher resolution usually has unwanted consequences. Added in are artifacts, pixelation, and weird chunks of color fun.
Resampling doesn’t always work.
High Resolution = Good
For raster images, always try to get at least a 300 dpi file at the actual size it will be reproduced.
For these file types, the larger the physical dimensions of the file get, the more megabytes the file may be in size. A 300 dpi file at 12″ x 12″ in size could be a 37MB+ file, and even larger if there are unflattened layers. That’s usually not something that can be emailed. I recommend either setting up an FTP portal on your website or getting a Dropbox account.
Raster image file size can be a good indicator for image quality.
So when a customer shoots you a raster image that is 112K is file size, you may be in trouble.
Raster images are best for photographs, complex illustrations, banner ads, web graphics, and content for social media. Adobe Photoshop is the recognized best industry platform for manipulating these photographic images, but other software programs can be used as well. In addition, many designers have switched to Affinity Photo as an alternative as it is lower in price than the Adobe Creative Cloud.
Your best defense in getting great files is educating your customers on what you need in order do a good job. Have some predesigned educational material on your website, and saved as a one-pager that you can email a customer.
Educating your customer is always a good idea.
Answer to the Statement – “This is all I have”
If you are in business for any length of time, you are going to run into this statement concerning a poor resolution art file.
“Sorry, but this is all I have.”
How are you dealing with this challenge?
You need a policy that is standard for dealing with this challenge. Do you charge to fix this situation? Are you spending valuable art department time cleaning up that logo, or do you simply rely on a service that can do it for $10?
More often than not, this conversation is about a low-resolution logo file that is needed for the customer’s order.
Which brings us to…
Vector
Vector images are based on math, not pixels. If you remember your high school geometry class, if you plot two points on a graph, you can connect them with a line. Plot four, connect all of them with a line, and you have a box shape. With that shape defined you can make the line or the box a color.
What’s great about this type of image is that it can be enlarged or reduced in size and never lose fidelity.
For this reason, vector images are always the best choice for logos and type.
Your art director isn’t crazy for constantly harping that logos coming in for orders have to be vector files. It’s a quality control thing. He’s just annoyed that for something so basic, he has to constantly repeat the raster vs vector art instructions on what’s needed.
I know you’ve heard this:
- Logos need to be vector files. This is so there aren’t any resolution challenges.
- All Pantone colors labeled. Specifying these in the logo art file means nobody has to guess or ask questions later.
- Fonts should be converted to outlines. This means that killer font you downloaded for free needs to be converted from that text file to vector paths so it reads correctly in the logo art file.
Vector files are always best when doing something with logos or text. The majority of designers use
Adobe Illustrator, but there is a big contingent of
CorelDraw users too. Also, like with Photoshop, the vector version of
Affinity Designer is seeing some growth. It’s really a personal preference at this point, but with Adobe shifting everything to their cloud format many designers don’t want to be saddled with that expense forever.
