Moire in Architectural Photography

I suspect most of you don't have a clue what "moire" is.

Well, it is a result of the digital age and digital cameras.  As most of you know, photosensors in most digital cameras are made up of pixels, light gathering spots on a sensor.  Pixels are usually arranged in a rectangular pattern.  (FYI, Fuji has a history of creating pixel arrangements that are not rectangular, with some diagonal, and a recent camera that has a "random" arrangement.)

When the subject has a repeating fine pattern, such as some fabrics, this pattern can interfere with the pixels in the camera sensor, creating images with strange patterns.  These image patterns are called moire.

Recently I had my first real experience with moire.  I was photographing an iPad screen, which was used by an environmental control system.  As most of you know, computer displays are also made up of small pixels, in a rectangular pattern.  As I photographed the iPad screen, I couldn't see the moire well on my small camera display, but when I got back to my office and examined the captures on my computer display, OMG, was it bad!  You can see it here, especially in the detail view.  I have circled the section of worst moire.

Original with obvious moire

Detail of the moire

I attempted to fix it, in Photoshop, using a few standard techniques.  However, because the image contained only moire in the right side of the image, none of them worked well.  I had to reshoot the screen.

The reshoot had to focus on eliminating the interaction of the pixels on the iPad with the camera pixels.  I also had to eliminate any reflections, which had other complications.  The easiest way to eliminate the moire was to tilt the camera, and orient the 2 sets of pixels at a large angle.  Sure enough, this worked great.

Here is the 2nd image:

Final image, captured at an angle

Now, you can see that I have an extra step in post-production; I have to straighten out the iPad.  Since we have a moire-free capture, tilting it back straight keeps it moire-free.

Straightened moire-free final image

So this solution was easy.  And now I'll be much more conscious of that nasty beast called moire.

Thanks for reading.

Greg Sprenger
Constructed Images LLC
www.constructedimages.net
greg@constructedimages.net