How to Add Pixels to an Image in Photoshop CS6
In Adobe Photoshop Creative Suite 6, you may need to upsample and add pixels to an image. This is a tricky process as it can sometimes make images blurry. To best avoid this problem, follow these steps:
With your desired image open, first choose Image→Duplicate to make a copy of your original. With the duplicate active, choose Image→Image Size.
The Image Size dialog box appears.
This is where the havoc happens. Be careful!
Make sure that the Resample Image option is selected.
The Width and Height in the Pixel Dimensions area are now text boxes into which you can enter values. They’re no longer fixed values as they are when Resample Image is deselected.
Enter a higher value for the resolution and, if desired, enter a higher value for the width or height.
The example has a resolution of 300 ppi.
The pixel dimensions increased dramatically, and so did the file size (from a mere 299.5K to 5.08MB).
If you get all discombobulated when working in the dialog box, press Alt (Option on the Mac). The Cancel button changes to a Reset button. Click it, and you’re back to where you started. This is a good shortcut to remember because it holds true for many of Photoshop’s dialog boxes.
Leave your Interpolation method set to Bicubic Automatic or Bicubic Smoother which is a good option when upsampling.
Photoshop now goes through its interpolation ritual and churns out a newly resampled image. Do a side-by-side comparison to the original, looking at both at 100% view. Your original should look a whole lot better than the resampled image. And, for a real shocker, try printing out the two images and seeing what kind of degradation takes place.