I took a group portrait photo today and it turned out great - until I was horrified to find that there is a strange visual effect going on with the tweed jacket of the guy right in the center of the picture. Here’s a section of the photo to illustrate what I’m talking about. There’s a psychedelic blue-and-yellow pattern on his sleeve. I have no idea why it looks this way. Everything else in the photo looks fine.
Here are the specs of the shot: It was taken with a Nikon D70s at f/4 and 1/60th shutter speed, 200 ISO, with an SB-400 flash tilted diagonally at the ceiling. Lens is a fixed 50mm Nikkor.
Why the hell did this happen? How can I ensure it doesn’t happen again?
Ok, I’m not a photography guy, but moire is a potential issue whenever you overlay one grid over another. In this case, the grid of the camera and the grid of the jacket.
I’d suggest you do a web search on moire and digital camera and study up. There’s no quick fix.
The effect is caused by the interference between the regular pattern of the weave on the jacket and the regular array of pixels in the digital camera. Often, it looks different depending on the resolution at which you view the image, especially if the original resolution is good enough to resolve the pattern of the weave. On film, the grain does not form a regular pattern, therefore you do not get the moiré effect.
It can be a problem with any digital camera, particularly older ones. Nikon only knows why the D70 and D70s were particularly bad - an interaction between the usual problem Anaglyph described and the in-camera JPEG encoding, I suspect.
I’m surprised you had it that bad with a raw file though. I used a D70 for many years and never saw it that bad except with JPEG. What are you using for your raw conversion? It’s usually not that hard to reduce by experimenting with sharpening and similar filters. There are plugins around for photoshop etc that will do it.
is the image sample you provided a screenshot, or a crop out of the original image, at the original resolution?
Reason for asking: I see this effect a lot when I’m working on my photos in image editors, but in my case, it always turns out to be interference happening in the process of rendering to the screen, rather than in the actual captured image. YMMV.
There is absolutely a way of fixing this in photoshop - saw it a few years ago but I have no idea where. I suspect it might have been a disc bundled with an early edition of Photoshop for Dummies, or similar.
It can be fixed. Hoping a Photoshop black belt wanders past soon…
As others have said, there’s no quick fix–particularly after the fact. However, if you can detect it at the time, you can often reduce the problem by changing the distances or zoom levels. The problem is because the pattern on the jacket is very nearly lining up with the photosites; if you increase the distance by, say, 40% and then crop the resulting image, it shouldn’t show the problem.
Other possibilities are defocusing the lens a bit, or tilting the camera by a small angle. Just about anything that disrupts the alignment of the grid will improve things.
I think it’s because most cameras only sample one of R,G,B at each pixel, then interpolate the missing pixels. Bayer filter - Wikipedia
Don’t have any solution though. Maybe you could try and take the photo slightly out of focus? Foveon has a sensor that measures RGB at each pixel, but their sensors have much lower resolution.
IMO, just take both digital and analog cameras and watch for stuff with patterns in the shot and switch to analog when you see it.
Take the shot you do have with moire and play with it in Photoshop. But the classic method of using gaussian blur to essentially “smudge” the moire also kills the pattern you’re trying to capture.
First off, it’s possible that the program you are using to convert the RAW to RGB is flawed in the same way as is the built-in version in your camera. Unfortunately, without the file, I can’t tell you whether this is the case. But look around and see if you can find other software to use, or see if you can mess with the settings of the program you currently use.
If you must work with it as is, Here’s all the advice I can spare. Since the affected area is monochromatic, the color is easy to fix, but the pattern is much more difficult. For the color, just select bad parts and colorize (an option in Hue/Saturation) them until they match the original, like so. If you’re okay with that, then your work is done.
If not, you can do part of mmm’s tutorial, with a few alterations. First off, make a copy of the original layer and do all you work on it. Then follow the directions up until it tells you to blur layers. Instead, copy the new L layer into both A and B, which will make your image monochrome. Invert the selection, and hit delete, which will show the original color, then invert again. Now select the original and make another copy. Desaturate that layer, so it’s in black and white. Now select the “de-moired” layer, and change it brightness and contrast until it matches with it’s black and white background. Once this is done, hide the monochrome layer, and use the colorize function to match the colored background.
Here’s the result. The moire pattern is still visible, but it’s a lot better. AFAIK, there’s no real way to fix that completely, but at least now it doesn’t stand out, and looks more like slight wrinkles.
One last thing: mmm, The Unsharp Mask is the name of the blog. That technique is not actually used in the instructions.
