Contents
Introduction
The theory behind the idea of having a cropped version of an image is that it was allow you to see how the detail of a large print will look by creating a test product that consists of a smaller segment of the full print that is printed at the same DPI as the full, large print.
When creating a smaller test print, you'll need to start with the full image and decide what size the full print would be. For this example it's a 40x30 print. And we're going to create a much smaller 12x8 print that shows a detailed part of the image.
The first step is to decide what the large print size is to be tested. In this case, this going to be 40x30. This shows up as one of the possible sizes that my image has in the art print store where I uploaded it. (Note: You can't do this for a print size larger that your image allows, so this should be one of the sizes listed on the product page in your Site Manager)
The next part is to determine the resolution of the image you uploaded to create this product. (You'll need to have a copy of this image to use when creating your cropped image, so make sure that you have this on hand from here on)
The details of how you'll find the resolution and crop the image will depend on the software you're using, and on the platform. The first instructions will walk you through using Photoshop, which is available for Windows and Mac. Then there will be instructions for the freeware windows application paintdotnet.
Using Photoshop
Once you've opened the image in Photoshop, the first thing to do is check the resolution of the image. You can find this by clicking on Image on the menu bar, and then on Image Size.
What you're looking for here are the Dimensions of the image, which will tell you the height and width of the image in pixels. Make a note of these, as they well be very important in determining what size (in pixels) your cropped image will be, and the DPI that this is being printed at.
First we'll need to determine the DPI value for when this image is printed at the desired size. There's some math involved here, but I'll try keep it simple.
Divide the pixel width of the image (3968) by the desired print width (40), and that's the DPI of the image when printed at that size.
3968÷40 = 99.2.
Now we need to determine how many pixels in size the crop needs to be.
First, let's determine the width of the cropped piece.
Divide the smaller width (12) by the full-sized width (40), and multiply the result by the width of the image in pixels (3968). The result may end in decimal, and in that case just round up to the next larger whole number.
(12÷40)×3968 = 0.3×3968 = 1190.4
Round the number up to 1191.
Now to determine the height of the cropped piece.
Divide the smaller height (8) by the full-sized height (30), and multiply the result by the height of the image in pixels (2976). Again, round this result if necessary.
(8÷30)×2976 = 0.267×2976 = 794.592
Round the number up to 795.
So the size we'll need to crop is 1191x795.
(If you're looking at a portrait crop - a crop which is taller than it is wider - then you can switch the sizes in those formula -
(8÷40)×3968 and (12÷30)×2976)
Now, the next thing to do is to go back to Photoshop, and from here we're going to go into Crop mode by pressing C on the keyboard. You'll see the new options showing above the image.
The first thing to do here is change the first option from Ratio to Width x Height x Resolution, and enter with width, height, and the PPI value we calculated above. For this example the values are 1191, 795, and 99.2. (You'll be replacing these with the width, height, and PPI values which you'll calculate for your image when you're setting up your image)
The next part may take some manual dexterity, as we're going to highlight an area that matches the desired cropped print size, in this case 12x8. You'll see the size displayed on the bottom-right corner of your selection. In this case it doesn't matter if you're slightly over size, as we're already so close to the target size and in this we no longer need to be pixel-accurate. Also, it doesn't matter where the selection is located as the box can be dragged to the location you wish to use.
Now the selection will have changed appearance. You can click and drag the light selection box to wherever you wish to place it, then click on the tick icon on the upper right to confirm your selection. For this you'll want to find a section which will give you a good idea of how the detailed areas of the image will look. I chose this area to get the detail of the goalposts on the background, the transition of the ground from light to dark, and the detail of the tree on the right hand side. What you'll select for your image will depend on the image you're using.
From here you will have the cropped image which you can save to your computer.
Using paint.NET (Windows-only)
Paintdotnet (also called paint.NET) is a free image editor available for Windows 7, 8.1, and 10. You can download this here: https://www.getpaint.net
Once you've opened your image in paintdotnet, the first thing to do is check the resolution of the image. You’ll see this at the bottom-center of the editor window. Make a note of these, as they will be very important in determining what size (in pixels) your cropped image will be.
First we need to determine how many pixels in size the crop needs to be.
Let's start by determining the width of the cropped piece.
Divide the smaller width (12) by the full-sized width (40), and multiply the result by the width of the image in pixels (3968). The result may end in decimal, and in that case just round up to the next larger whole number.
(12÷40)×3968 = 0.3×3968 = 1190.4
Round the number up to 1191.
Now to determine the height of the cropped piece.
Divide the smaller height (8) by the full-sized height (30), and multiply the result by the height of the image in pixels (2976). Again, round this result if necessary.
(8÷30)×2976 = 0.267×2976 = 794.592
Round the number up to 795.
So the size we'll need to crop is 1191x795.
(If you're looking at a portrait crop - a crop which is taller than it is wider - then you can switch the sizes in those formula
(8÷40)×3968 and (12÷30)×2976)
The next part may take some manual dexterity, as we're going to highlight an area that matches the desired cropped print size, in this case 1191x795. First press S to select the Rectangular Select mode or click on the Rectangular Select icon on the toolbar (in the top-left position).
You'll see the size of your selection displayed on the bottom-right corner of the paintdotnet window. In this case it doesn't matter if you're a little over size, as we'll be cropping this next. Don’t worry too much about positioning this exactly, but you’ll want it to be roughly centered on the section of the print you wish to print. You'll want to find a section which will give you a good representation of different areas of detail. I chose this area to get the detail of the goalposts on the background, the transition of the ground from light to dark, and the detail of the tree on the right hand side. What you'll select here will depend on what is on the image you're using.
Now to create the initial crop, click on Image on the menu, and then on Crop to Selection.
From here you will have the cropped image which you can save to your computer.
How to use your new cropped image
Once you have the cropped image saved - being sure not to overwrite the original image - and upload it to your site. This won't need to be added to a gallery, as you will just be ordering this as a wholesale order, as an 8x12 print. You should use an inexpensive media for this; matte photo paper is probably the cheapest option here, although a glossy photo print can be used instead if you’d like to see it with a gloss finish.
For more information about how to place a wholesale order you may find this article to be useful: https://artstorefrontssupport.zendesk.com/hc/en-us/articles/360028831931-Everything-You-Need-To-Know-About-Retail-Self-Made-and-Wholesale-Orders