Ramblings

Why Photoshop isn't a vector tool.

I've seen a great deal of argument referring to Photoshop vector data as being the same as Illustrator vector data. It really is not. While Photoshop does have some basic vector tools there are very important differences between Photoshop vectors and Illustrator vectors. I recently posted the following on a web site explaining the difference and I thought it may be useful here as well.

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Photoshop is a raster application that has a few vector tools. It does not create true vector content. When using the vector tools in Photoshop, you do have the ability to create vector containers full of raster data. There's a HUGE difference.

A true vector application creates 100% vector files, unless you import something that's raster. With true vector files, they can be enlarged and reduced to any size and never loose 1 iota of quality. This is not true for Photoshop files, in any format.

This becomes terribly apparent in some cases. One being a logo. If you draw a vector shape in Photoshop, then use a bunch of fancy layer styles as people often do - bevel and emboss, satin, inner shadow...for the sake of of this example I'll only refer to layer style items that effect the inside of the shape. Now, save that file as a photoshop PDF, PSD, or EPS (the three Photoshop formats that will support vector data).

Now, create something similar in Illustrator. Granted things like satin and bevel and emboss are not easily pulled off in Illustrator, but it is possible. Save that file as an illustrator EPS (a true vector format).

Now, place both the Photoshop file and illustrator file in an Indesign document. Enlarge both images by 800% and print them. You'll see an absolutely clear difference. The outside edges of the Photoshop image will be crisp and clear, but all those interior items will be heavily pixelated. This is because it's raster content inside a vector container. The print of the Illustrator file will be clear and crisp everywhere because it's an actual vector based file.

Assume the printer has a 300dpi resolution......

When you print a true vector image, like one from Illustrator, the printer is told to start at point x1y1 then move, say 2 inches, left from that point to point x600y1 (300 points [dots] per inch times 2) and then fill all the point in between with a specific color, in this case black. This makes a straight black path between x1y1 and x600y1. The actual number of points is mathematically calculated before printing begins. So no matter how large or small your image is, the math is always correct for the output device. This makes the file resolution independent.

When printing raster content (like the interior of a Photoshop shape layer) the printer is told to print the point at x1y1 as black, then x2y1 as black, then x3y1 as black, then x4y1 as black, etc. One at a time the pixel data is sent to the printer. If that pixel data does not meet the output resolution of your printer you get what is known as "broken pixels" or pixels that are stretched or squashed to fit a specific dimension. This makes your image resolution dependent. Only the exterior bounding shape is sent as vector data.

With vector content in Photoshop, only the vector content is resolution independent, anything inside that vector shape is still bound by traditional raster restrictions. This is why, for a logo, Photoshop is absolutely never the proper tool to use. If you can not create the logo in Illustrator it's bound by raster restrictions and will not work at some sizes. A logo should work at any size between 1 inch wide and 6 feet wide. Sure you can simply keep recreating the logo at specific sizes for specific output, but why would anyone want to do all that extra work when all they really need to do is use the proper tool from the beginning? When I hear the term "logo" the only thing I think of working with is Illustrator. If you've paid for a logo and not received a vector file, then ask for one.

If you were a plumber you'd have several tools - a monkey wrench, screwdrivers, a pair of pliers, maybe a hammer, pipe wrench, etc. Each tool has a specific function and is used for a specific result. As a designer you need more than 1 tool. Photoshop is not the be-all-end-all in terms of creation. Never has been and never will be. you'll only do better by extending your set of tools. Using Photoshop for a logo is like using a pair of pliers as a hammer. Yes. It works. Is it the right tool? No. Will it possibly break whatever it is your pounding on, there's a possibility. Plus, hitting your thumb with pliers just hurts.

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