here 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 the 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 5 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 to, 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. Which 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, then we would want this to be 300PPI @ 4 inches. Note that you can use the dropdown and select your unit of measurement. If it's on pixels, you can change it to inches, as above.
I am going to uncheck resample. This will keep the true number of pixels inside the amount of inches you choose. If I change this to 10 inches, then you will see my resolution becomes 300. So, many more pixels are are within each inch, thus providing more detail per inch and keep 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 was only 150 PPI, just going up 2 more inches will 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, and that 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 4 sides of you artwork to gauge the true size. If you have snapping enabled, the crop box will automatically snap to each edge. 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. Many times 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 4 sides.
Do you have a background?
If you have a background, that needs to be removed because its not part of the print, there are many ways to get rid of them 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 to 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. The important setting to pay attention to with this tool is the contagious checkbox up top. If it's not checked it will select pixels of that near color anywhere within the art. If it is 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 servers two purposes. It can mimic the tee color to gauge the final print, and it can provide an obvious background that bright, so we can tell exactly what's print 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 3 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
When you selected the curves adjustment layer, you must have also noticed the other layer adjustment options. 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.