Trying to figure out the resolution of an image but you don’t have Photoshop? You can easily configure Windows to show you the resolution!
First, open File Explorer, or “Computer,” so you see a screen like this:
Second, click on the area shown by the red arrow on the above image, and choose “Details” – Then the window should look like this:
Third, right-click on the area indicated by the red arrow. A box will pop up with the word “More” at the bottom. Click on that. You should see a pop-up dialog box that looks like this:
Scroll down until you come to an item that is called “Horizontal Resolution” and click the checkbox next to it. Then click OK.
That’s it! The resolution of your images should now appear in the details list for your images!
If you are just putting images on the web, they can have a resolution as low as 72 dpi and still look fine on a regular computer monitor. If you’re putting images in an eBook or printed book, however, a resolution of at least 300 dpi is best (much more than that and the gain is minimal compared to the increase in file size).
As a side note, it is sometimes possible to improve the way an image prints in a book by “messing around” with the resolution, but usually you have to start with a high-resolution to begin with.