Colorful QR Codes that will Scan
If you want to make colorful QR codes that will still scan. There are many things that you need to take into account like colors, contrast, and length of the URL or number of characters that are in the source data. The source data or URL is important even if you aren't making colorful QR codes.
Thus, the first step in making colorful QR codes is shortening the URL. I would use Google URL shortener. The more characters there are in the URL the more complicated the QR code will be and the more trouble people will have scanning it.
Next, try to find a website that generates codes that scan and directs user straight to the destination page with no redirects. I usually use GOQR. After generating the code you can edit the QR in your preferred photo editing software.
This is where you have to decide what colors you want to use. The key is to choose two high contrasting colors. Colors on the opposite ends of the color wheel tend to contrast well. The primary colors will also contrast decently with each other. Choose the color that seems "darker" and replace all of the blacks in the QR with that color. Choose the color that seems "lighter" and replace all of the whites with that color. After you are finishing changing the colors, test it with your smartphone.
It is very difficult to get consumers to take out their smartphones, start up an app, and scan a QR code. This makes it even more important to create rich and vibrant QR codes that can attract a lot of attention. Remember, a well placed QR code on a billboard, bus stop, or magazine ad can transport a customer straight to your digital doorstep.