Coasters are handled differently than other media that are set up on your site. In most cases your vendor will create a print based on the size that your customer wishes to order their print, and without major cropping regardless of the aspect ratio of the image.

For coasters your images are all going to be cropped square, and will require a certain distance of unimportant detail (or space which is blank) around the edges of the image.

If you wish to offer these products, you wish to look at setting up special versions of your images to be used exclusively for coasters. The benefits of this are that you’ll be able to make sure that the images are centered and cropped on the most appropriate section of each image, as well as well as making changes to the edges or sides where necessary to avoid detail being lost or elements like signatures being cropped.

There are two basic types of images that will each require different treatment.

The first is where there is sufficient content around the focus of the image to be able to crop the image to be square and it will be usable right away.
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The second is more complicated, as the image may be cropped so close to the detail of the image that it may be necessary to add blank space around the image in order to fit it correctly in the required layout. This can be especially problematic in pieces where the image is far from 1:1 in aspect ratio. Here you need to add content to make the image fit.

For an image with a solid background like this, it’s not as difficult as you can simply extend the colour of the background to fill up the extra area.

Unfortunately this gets trickier if the image has a textured background and is cropped close to the edges. For this you’ll need to utilise specialised methods and creative workarounds. Please keep in mind that not all images are going to be able to be reformatted for use as a coaster, so for some images it’s just not going to be possible to “fix” an image. We can make suggestions, but they may require that you have access to specific software and that your images are laid out in such a way that these methods will work with them, and we cannot guarantee that they’ll work for everyone or all images.

Additionally you should make sure that you don’t have anything in the corners such as signatures or other important design elements. As the corners are rounded when they’re manufactured, anything located there may end up being cropped. Instead try positioning these flourishes along the center of the edges, or inset from the corners.

The important thing here is to have an extra ⅛” or so around the area of your image that is going to be the center of the coaster once printed. The middle will be 1125x1125px in size (3.75x3.75” at 300PPI), and with the extra area required you’ll want around 1200x1200px in total.

This list contains instructions on how to crop your images using different applications:

In this case we’re taking the original image, and resizing to a specific width or height. Then we’ll be expanding the canvas around the image to make the image square, and filling it with the background color of the image.

I’m going to walk you through the process of setting this up using the Pixlr website, as it’s free and very easy to use.

First, load up Pixlr X: https://pixlr.com/x/

When the page has loaded, you can drag and drop the image you wish to edit onto the page to open it.

The first step is going to be to change the canvas size of the image. We do this by clicking on the Properties button on the left hand side of the page.
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In the new panel which opens, click on the Canvas Size button.

What you’re going to enter on this section will depend on the resolution of your image. If your image is over 1200x1200px in size, you may wish to add 200px the whichever dimension is larger (or more for very large images, over 2500px in size), and then put the same value into the other field.

The example image I’m using is below the 1200x1200 recommended size for coasters, so in this case I can just enter 1200x1200 and allow Pixlr to expand the canvas, after which I’ll click on Apply.

You may need to scroll out a little with your mouse wheel, but you’ll see the larger image which has a larger and transparent area added around it.

Now we’re going to add a colour to this transparent section but clicking on the switch just to the right of the word Background.

Now we need to change the colour being applied. You can click on any of the coloured dots (or on the white bar), and this will open the colour selection dialogue. There is a grey button below the rainbow bar and to the right which you should click on next.

This will enable eye dropper mode, where the cursor changes to a large cross (not shown in this screenshot) with a circle to the upper right showing the colour which will be selected.

When I click on the purple background from the original image, it replaces the white with this colour. As this is the last step, you can click on the Save button at the bottom of the window.

Now you can save the image, and we would recommend saving it as a JPG at 100% quality and High settings. Then when you click on the Download button the image will be downloaded to your computer, from where you can upload it to your site to use as a coaster source image.

Paint.net: https://screencast-o-matic.com/watch/cY6QFvKsjj

Pixlr: https://screencast-o-matic.com/watch/cYlUDf8P0U

Here we’re looking at images which don’t have simple single-colour backgrounds. We’re going to examine how it may be possible to use specific tools to build additional background content. Keep in mind that if you don’t have access to appropriate software, this may not be an option for you. In addition, some images may just not be possible to crop and format for use with a coaster as they won’t work as a square image or would require the creation of background texture that is beyond our scope to reproduce.

These are basic instructions for use with Photoshop CC. The details of how you’ll need to set this up will depend on your image - this example expands and fills the canvas of the image using the Content-Aware Fill functionality of this application. For more information about this function, this article is a good place to start: https://helpx.adobe.com/photoshop/using/content-aware-fill.html

First, open your image in Photoshop.

Next, we’re going to want to make the canvas square. Click on the Image menu item, and select Canvas Size.

On the dialogue window that’s opened, change the unit of measurement to Pixels.

Now, as we want to make this image square, we’re going to replace the smaller size (826) with the larger one (1609), so it will be the same width and height.

In this case I’m also going to change the colour of the canvas extension, so it’ll be easier to select in the next step - in this case, I’m going to be selecting Black.

After clicking OK, the expanding image will be shown, with black sections on each side showing where new background content needs to be added.

Now it’s time to select the left-hand side in order to fill it. First select the Rectangular Marquee tool from the toolbar on the top-left.

Click slightly above and to the left of the top-left corner of the image, and select the entire left-hand side of the image, making sure to also include a little bit of the very left-hand edge of the image itself..

Then click on Edit on the menu bar, and select Content Aware Fill.

You’ll be shown a preview of the generated fill, and if you’re happy with the result, you can click on the OK button on the bottom right.

Now you can repeat the process for the right-hand side of the image.

If the fill looks alright you can then click on OK to apply it to the image.

Now the modified image is almost correct, but it needs to have the background and two other layers flattened down before it can be saved. Click on Layer on the menu bar, and then select Flatten Image.

Click on File on the menu bar, then on Save As.

On the next page you can change the filename, and we recommend saving it as a JPG and you should also embed the color profile (which should be either sRGB or Adobe RGB).

Finally, these options will give you the best quality image saved correctly.

The resultant image is ready to upload to your site to use, although you may wish to align and crop it further.

Photoshop CC: https://screencast-o-matic.com/watch/cY6QF9KsYz