There are some quick tips you can utilize to verify your artwork is ready to send to print. The opposite can also be said. You might be verifying that the quality is too low to send to print without some work. Let's talk about some things to quickly improve your artwork or verify it's ready to go. Here are five tips to help you prepare artwork in Photoshop.
Verify your size and resolution
This should be one of the first things you verify when receiving artwork. You want to check two important details within the art, size, and resolution. To do this, in your menu up top, go to Image > Image Size...
Ideally, you want a resolution of 300 pixels per inch, and then the width and height would be true to print. This means you should aim for 300 PPI @ 12 inches for a full front. Or whatever your shop considers a full front size. Or if we were printing a left chest print, we would want this to be 300PPI @ 4 inches. Note that you can use the dropdown and select your unit of measurement. You can change it to inches if it's on pixels, as above.
I am going to uncheck resample. This will keep the true number of pixels inside the number of inches you choose. If I change this to 10 inches, then you will see my resolution becomes 300. So, many more pixels are within each inch, thus providing more detail per inch and keeping our edges sharp for print.
In this case, the math works out. But you must note because Photoshop is a raster-based program, you can not just scale images up. This will severely affect the quality of your art. At 300 PPI like this, I could bump up from 10 inches wide to 12 inches. There is a little bit of wiggle room. But if my image were only 150 PPI, just going up two more inches would start to show and degrade the image. You can, however, shrink downwards without degrading. For example, if you had a large back print with a matching left chest print.
The most important part of this to take away, which applies in the real world, is that you can not take random images from the web, open them in Photoshop, and then bump them up to 12 inches big and 300 DPI and expect a good print. This you could only do with vector artwork. As we recommended 300 PPI above, 200 may be passable. Anything less, and you are flirting with a possible bad print.
Trim/Crop Your Artwork
When you check the measurements of your artwork, you will need to measure it from the edge of the artwork to the other edge of the artwork. You would not measure the background edges, as this is probably not a part of your print.
You can manually use the crop tool and crop all four sides of your artwork to gauge the true size. The crop box will automatically snap to each edge if snapping is enabled. Some rip software will allow you to crop from within, but it's better to have your artwork as prepared as possible beforehand and let the rip just handing printing.
Or, for a more advanced way, use the Trim option located under the image menu. After selecting Trim... a box pops up. You can "trim" based on either transparent pixels (no background, appears with grey/white checkered pattern behind art) or a color. Often black or white, which happens a lot, or to represent the garment color. Once you do this, Photoshop trims away the blank areas, leaving your artwork at the very edge of all four sides.
Do you have a background?
If you have a background that needs to be removed because it's not part of the print, there are many ways to remove it in Photoshop. Our favorite is the magic eraser tool. This is located with the regular erase tool. You might have to click and hold to see this tool pop up. This allows you to click on the background color, and it will remove any pixels of those colors. You can use the tolerance setting at the top to choose how particular it is, but the default setting of 32 works well enough in most cases. A lower number would be more picky about the shades, while a higher number would be more lenient. With this tool, the contagious checkbox up top is an important setting to pay attention to. It will select pixels of that near color anywhere within the art if it's not checked. If checked, it would only select that color and its selection that directly touches it.
In the image below, you see that I have two layers. One is my artwork that will print, and the other is a bright green background. This color you use for your background serves two purposes. It can mimic the tee color to gauge the final print and provide an obvious background that bright, so we can tell exactly what's printed and make sure we didn't miss any random piece of art when we deleted the original background.
Set a Black Point via Curves
Unless purposely going for a muted look, you should make sure your black artwork is actually black. Sometimes, you may open art that isn't quite that blackest black. To do this, go into your layers panel and select a new adjustment layer for curves. Once you have that open above the layers, you will see three eye droppers on the left side. Select the top one. This gives you an eye-dropper. Now sample anywhere in the artwork that is supposed to be pure black. And the adjustment is automatically made. It will be made on the layer above. You can click the eye icon off and on to see the difference with and without the black point.
Try an Adjustment Layer
You must have also noticed the other layer adjustment options when you selected the curves adjustment layer. Some of the others can also be handy, such as the brightness/contrast or vibrance. The nice thing about these adjustment layers is that you can try them, and they do not directly affect the artwork. They are on a separate layer, so you can play with these and experiment without actually modifying the original artwork on the original layer.