Understanding Artwork File types

.jpg, .psd, .png,. bmp., .tiff...raster image, bitmap image, vector image....what the heck does all of this mean?!?

When it comes to artwork or image files, there is a lot of confusion as to what each file type extension means, the differences between them, and why/when you would use each of them.

Perhaps the most important thing to understand, first, is the difference between a raster or bitmap image and a vector image. The simplest and most basic distinction, is that a raster or bitmap image is made up of pixels, whereas a vector image is uses anchor points and paths to create an image. Where a pixel is basically a square filled with colours and information, vector paths and curves are more like numerical wire frames and coordinates of an image. This distinction is very important to understand when it comes to reproducing images digitally.

Why, you may ask? The best example may be, when a client comes to us with a Jpeg file that they pulled off the internet that is only 72dpi (dots or pixels per inch) and 250x250 pixels in size, which they want to have blown up to 10" x 10" and printed onto a t-shirt, and then wonder why the image is blurry and "pixelated." An image that may look great on a web page that is 250x250 pixels in size at 72dpi, in reality, is only 3.47" x 3.47" in size. This means that we would need to blow up that image by 3 times in order to make it 10" x10". Typically, the most that a raster image can be blown up before it starts to look blurry or defective, is about 2 times if it is a good quality image, unless it is a very high resolution image, greater than 300 dpi. Most images on the web are only 72 dpi, so the best way to determine if an image can be blown up, is to view it in your photo viewer and zoom in 200-300%. This will how you exactly how the image will look blown up on a shirt or other medium.

Where raster or bitmap images are most suitably produced at the size which they are intended to be printed or displayed at, vector images can be scaled to larger sizes without losing quality and sharpness of the image. Think of vector images being more like the blueprint of the image as opposed to the actual tiles of details. Most of the printed media that you see in displays, especially large format billboards and the like, are created using vector images. This is how they retain their sharpness at such a large scale.

So then what of resolution and image size?

Chances are, that unless you are working with a graphic designer to create your artwork and images from scratch in vector format, the images and photographs you are working with will be raster images. That's okay though! Especially considering that when printing on garments, we're typically not talking about a huge printing landscape. With that in mind, here are some basics to consider when selecting or creating images or photographs for garment printing-

1. Resolution is King! The higher, the better. 300dpi is an ideal resolution to supply us with, 100 dpi would be the minimum. Typically, we would not require images with higher than 300dpi resolution, unless it is a smaller sized image that you want blown up considerably.

2. At 300dpi, 1000 pixels equals 3.333". An image that is 1000x1000 pixels, in actuality is only 3.3"x3.3". To put that into context, our DTG printer can print an image up to 16"x20", or 4800x6000 pixels. An image that is 10" wide would be 3000 pixels wide. This is a great reference for calculating how large your images should be, relative to how large you desire to have them printed. So as mentioned before, if you come to us with an image that is 250x250 pixels in size at only a 72dpi resolution, we simply will not be able to reproduce that image with any degree of quality for anything larger than perhaps a small crest over a shirt pocket, or something of the like.

3. Jpeg files can only have a solid colour background, PNG files can have a transparent background. So, Jpeg's for photographs, PNG's for logos or artwork images that are not square or rectangular in shape. Whenever possible, supply us with Photoshop .psd files for images, regardless of whether they are photographs or artwork images.

Have a specific question regarding the images you want to use? Call or email us today!


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