Open the picture you want to pixelate in Photoshop.
Select "Ctrl-Alt-I" to open the Image size window.
Change the width and height of your picture to a very small number, such as 100 for width and 120 for height, and then click "OK."
Select "Ctrl-Alt-I" to open the Image size window.
Click on the "pixels" title next to the width and height selections and change it to "Percent."
Type in "300" in the width and height selections, and click "OK."
Save the file and have it printed at a print shop that can create wall-size images.
Navigate to the IXXI website and select "start" under "Create your own IXXI." If the site appears first in Dutch, click "ENG" near the top of the page.
Click "select product" under "IXXI Collage."
Click "start" under the size of wall art you would like.
Click "Browse," and then select the images you want to use in your wall art from the files on your computer. Hold down your "Command" key to select more than one image at a time.
Click "Upload" once you've selected all your photos.
Click and drag your photos to move them on the grid to your specifications. When you've created the design you want, click "Confirm Order" to pay and have the item shipped to you.