How to size your image for printing
First, open your image in Photoshop.
Next, on the top tool bar, go to 'Image'. Then slide down and click 'Image Size'.
This will open the 'Image Size' dialogue window.
Here we can see the image size properties in pixels or measurement units like inches and centimetres. We can also see the Resolution of the image.
To change the size of the image, choose inches or centimetres, then input the desired width or height. When the 'Constrain Proportions' check box is ticked, entering one value will automatically adjust the other.
At this point you can see if your image conforms to the aspect ration of the print size you want. Often traditional print sizes like 8”x10” or 16”x20” will require cropping. See Adobe’s excellent tutorial on Using the Crop Tool in Photoshop.
In the “Image Size” dialogue window you can also set the resolution. Typical print output should be no less than 240 dpi for photographic images.
During this entire procedure make sure the “Resampling” checkbox is ticked. This will allow Photoshop to ‘grow’ pixels when enlarging.
After resizing, zoom in to 50%. This will give you a better understanding of how your image will look in terms of visual quality once it’s printed.
Remember to include any borders you may want on the print (see our How To article “How to Add Borders to Your Image ”).