Fortunately many QR code readers are very tolerant of colour variations and the codes themselves incorporate a certain amount of tolerance to error in print quality. This means that it is possible to tweak a codes visually as long as you are sure that it is not going to be used on something that is mission critical. So if your code is going to be used on a manned mission to Mars stick to the black and white version.
Using any image as a base the following method should give you a reasonable result:
- Load your image into the GIMP image editing program.
- Grab a copy of the QR-Code image by using right-click over the image on the view page of your q-action account.
- Back to Gimp and paste as a new layer.
- Scale the layer making sure interpolation is set to none. The code will get unhelpfully distorted if you use any other setting.
- Add a layer mask using image greyscale option.
- Adjust brightness and contrast until the result looks OK.
- Crop and save the image.
I reset this q-action code to point to the you-tube video of how it was made using these instructions.
And this is the video: