Moiré

How to Remove Moiré in Photoshop

Feb

2012

February 17, 2012

In this article, I will show you how you can reduce the effect of moiré in Adobe Photoshop. With the release of the Nikon D800E, which has a different low-pass filter compared to the regular version of the D800 (see Nikon D800 vs D800E), it seems like Nikon opened up a can of worms as it relates to a phenomenon known as “moiré“. For the first time, Nikon is letting photographers pick between two versions of the same camera: one that yields sharper images at a cost of potentially having moiré in images (D800E) and one that yields slightly softer images but has no issues with moiré (D800). This quickly created tremendous interest from photographers, many of whom never even heard of the term “moiré” before the Nikon D800E. Questions started pouring in from everywhere and I spent quite a bit of time trying to explain what moiré is all about and how one could avoid or reduce its effect. This seems to be a primary concern for landscape and macro photographers that also enjoy photographing architecture and portraits (where moiré is seen quite often). Below you will find detailed instructions on how to reduce the effect of moiré in Photoshop.

Can Moiré be completely removed in Photoshop?

Unlike Lightroom 4, which has a built-in tool to reduce moire (and in some mild cases even eliminate it), Photoshop has no automated way of reducing or removing moire. Because of this, there are literally dozens of different methods you can use to deal with moire. I have tried a number of them and I found the below method to work best for the worst moire-infested photographs out there. Most other methods use some sort of blurring technique that actually degrades image quality, which is why I prefer this one instead. If you work with the original file (RAW is preferred), you will definitely get better results than if you work with a small JPEG image (as I will be doing below). While it is possible to completely remove moire in Photoshop, the process can be very time consuming and painful. This is the reason why I have been recommending most of our readers to buy the regular version of the Nikon D800 instead of the D800E. The latter is a specialized tool for dedicated landscape and macro photographers that want to get the best out of their equipment. The last thing you want is introduce another step to your workflow in order to clean up moiré, just because you picked up the wrong camera.

Step One: Remove the Rainbow Pattern

Removing moire in Photoshop is done in two steps – the first one removes the rainbow pattern of moire and the second one takes care of the Luminance channel pattern. Let’s get started with the same jacket image I presented in “what is moiré” article. I decided to use this image, because it has a very strong moiré pattern with yellow and green rainbow discolorations. This type of moiré is pretty much a worst-case scenario:

(Image courtesy of photo.net)

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Filed Under: Post Processing Tagged With: Moiré

How to Reduce Moiré in Lightroom 4

Feb

2012

February 10, 2012

By Nasim Mansurov 29 Comments

In this article, I will show you how you can reduce the effect of moiré in the upcoming version of Lightroom 4. With the release of the Nikon D800E, which has a different low-pass filter compared to the regular version of the D800 (see Nikon D800 vs D800E), it seems like Nikon opened up a can of worms as it relates to a phenomenon known as “moiré“. For the first time, Nikon is letting photographers pick between two versions of the same camera: one that yields sharper images at a cost of potentially having moiré in images (D800E) and one that yields slightly softer images but has no issues with moiré (D800). This quickly created tremendous interest from photographers, many of whom never even heard of the term “moiré” before the Nikon D800E. Questions started pouring in from everywhere and I spent quite a bit of time trying to explain what moiré is all about and how one could avoid or reduce its effect. This seems to be a primary concern for landscape and macro photographers that also enjoy photographing architecture and portraits (where moiré is seen quite often). Below you will find detailed instructions on how to reduce the effect of moiré in Lightroom.

Can Moiré be completely removed in Lightroom?

As you may have noticed, I used the word “reduce” instead of “remove” in the header of this article. That’s because the moiré pattern often cannot be completely eliminated with a non-destructive editing application like Lightroom (except for mild cases of moiré), especially when moire damages the texture. Photographs with very visible and large moiré patterns in the Luminance Channel can only be completely fixed in Photoshop, which is a cumbersome and time-consuming process. In many cases, you have to sacrifice details to remove moiré completely. This is the reason why I have been recommending most of our readers to buy the regular version of the Nikon D800 instead of the D800E. The latter is a specialized tool for dedicated landscape and macro photographers that want to get the best out of their equipment. The last thing you want is introduce another step to your workflow in order to clean up moiré, just because you picked up the wrong camera.

Please note that the below instructions will only work with Lightroom 4. The previous versions of Lightroom do not have any moire reduction tools. Please also note that the below tool works best with the original RAW file.

Using Adjustment Brush to Reduce Moiré in Lightroom 4

Let’s get started with the same jacket image I presented in “what is moiré” article. I decided to use this image, because it has a very strong moiré pattern with a yellow and green rainbow discolorations. This type of moiré is very hard to fix in post-processing and it requires use of Adobe Photoshop to completely get rid of it. Here is the image we will be working on:

(Image courtesy of photo.net)

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Filed Under: Post Processing Tagged With: Adobe, Lightroom, Lightroom 4, Moiré

How to Avoid Moiré

Feb

2012

By Nasim Mansurov 17 Comments

In this quick article, I will talk about how to avoid moiré if your camera is not equipped with a low-pass / anti-aliasing filter, or if it has a special low-pass filter like the Nikon D800E that is also prone to moire. Moiré can be quite painful to deal with in post-processing, so it is best to avoid it in first place. Below you will find a list of steps you can take to avoid moiré while shooting patterns.

Analyze patterns in your images on your camera’s LCD at 100% view – while looking at your images on the camera LCD at 100% view can be very inefficient and time-consuming (especially on the Nikon D800E with its massive 36.3 megapixel images), if you are shooting anything with repeating patterns, you need to know whether there is moiré in your images or not. Looking at the thumbnail on the LCD might not reveal moiré, so you will have to zoom in to see it. Very strong / nasty moiré might be visible even at 50% view or less, while you will only spot mild moiré at 100% pixel level view. If you see moiré and want to avoid it, proceed to step #2 below.
Quick useful tip: if you own an advanced Nikon DSLR like Nikon D300s or higher, you can set the multi-selector center button on the back of the camera to instantly show 100% view without having to press the zoom button several times. You have to enable this feature here: Custom Settings Menu->Controls->Multi selector center button->Playback mode->Zoom on/off->High magnification. Once set, you will be able to zoom in to your images at 100% by simply pressing this button in playback mode.
Change camera to subject distance or adjust focal length – if moiré is visible in your image, the best thing you can do is change the distance to your subject. You can either physically move closer or away from your subject, or you can zoom in/out with your lens. Remember, moiré only happens when the pattern you are photographing exceeds sensor resolution, so all you have to do is move to a safer distance. Sometimes this means moving just inches away from your subject.
Adjust focus to a different area – while this is not always practical, adjusting the focus a little away from the patterns will remove moiré.
Change the angle of the camera – simply changing the angle of the camera a little can completely eliminate even very strong moiré patterns.
Stop down the lens to f/11-f/16 – when lenses are stopped down beyond a certain aperture (depending on the lens and the sensor size), an optical phenomenon known as “diffraction” kicks in. Diffraction effectively reduces resolution, which also eliminates moiré. While I would personally avoid doing this, if you cannot change your subject to camera distance or adjust your focal length for whatever reason, this technique surely works.

If you did not do any of the above and ended up with an image that has visible moiré, then your only option is to try to fix it in post-processing.

Filed Under: Photography Techniques Tagged With: Advanced Photography Tips, Moiré

Nikon D800E will ship with Capture NX 2

Feb

2012

February 7, 2012

By Nasim Mansurov 25 Comments

The Nikon D800E is generating a lot of interest among many landscape and macro photographers and one question that has been popping up a lot, is why the Nikon D800E is $300 more expensive than the Nikon D800? I received a number of comments like “why is Nikon charging extra for something the D800 does not have?” (meaning why Nikon charges extra money for a camera without an anti-aliasing / low-pass filter). In fact, both the Nikon D800 and the D800E have anti-aliasing filters (see the illustration below), it is just that the Nikon D800E has two of the filters reversed that cancel each other out. So some of the extra charge is coming from the required change in the manufacturing process. Additionally, according to DPReview’s “Nikon D800 Preview” they posted today, the Nikon D800E version will ship with the Nikon Capture NX 2 software, which costs around $129.95 retail.

Now about that low-pass filter on the Nikon D800E – both the D800 and the D800E have low-pass filters, but they behave differently. Typical Nikon low-pass filters actually contain of 3 different layers, as shown on the top illustration below:

As light rays reach the first “horizontal low-pass filter”, they get split in two, horizontally. Next, they go through an infrared absorption filter (illustrated in green color). After that, the light rays go through the “second vertical low-pass filter”, which further splits the light rays vertically. This light ray conversion process essentially causes blurring of the details.

Now with the Nikon D800E model, Nikon took an interesting approach. We know that the full low-pass filter cannot be completely removed, because it would cause the focal plane to move as well; plus, the camera still needs to be able to reflect infrared light rays. Instead of making a single filter with one layer, Nikon decided to still use three layers, but with two layers canceling each other out. As light rays get split into two with a vertical low-pass filter, then through the IR absorption filter, those same light rays get converged back when passing through a reversed vertical low-pass filter. Hence, instead of getting blurred details as in the first illustration, we get the full resolution.

I am not sure if the above method is the best way to deal with the issue, but I suspect that Nikon decided to take this route for cost reasons. It would probably be more expensive to produce a single IR absorption filter layer coated on both sides, than continue to use the same layers, but in a different configuration.

The above information will be added to my Nikon D800 vs D800E article I posted last night.

Filed Under: Cameras and Lenses Tagged With: Anti-Aliasing Filter, Capture NX, DSLR Camera, Moiré, Nikon, Nikon D800, Nikon D800E

Nikon D800 vs D800E

Feb

2012

February 6, 2012

By Nasim Mansurov 309 Comments

Now that both the Nikon D800 and Nikon D800E are available, many of our readers are wondering which one to get. In this Nikon D800 vs D800E article, I will explain differences between the two cameras and talk about which camera to buy for which situation. Both cameras are identical, except for one major difference, which is why there is a price difference: the Nikon D800 has an anti-aliasing filter, while the Nikon D800E does not. In short, an anti-aliasing filter effectively removes Moiré (see below on what Moiré is), so the Nikon D800 will not have any problems with it, while the Nikon D800E cannot deal with it, so you will have to deal with it in post-processing.

What is Moiré?

Moiré pattern occurs when a scene or an object that is being photographed contains repetitive details (such as lines, dots, etc) that exceed the sensor resolution. As a result, the camera produces a strange-looking wavy pattern as seen below:

(Image courtesy of photo.net)

What is Moiré?

Jan

2012

January 4, 2012

By Nasim Mansurov 7 Comments

(Image courtesy of photo.net)

See how noticeable the moiré pattern is on the jacket? That’s moiré for you, at its worst. Moiré is almost never seen in nature, but is very common in everyday objects and items around us – you might see it in all kinds of fabric, straight hair, architecture, etc. You might have even seen it on your television. In photography, moiré happens mostly because of the way light reaches the sensor and how the sensor interprets the light through the bayer interpolation filter.

While there are methods to effectively reduce moiré, there is no easy way to completely remove it in post-processing software. Lightroom 4 will ship with a moiré reduction tool and Nikon will also ship its next version of Capture NX with built-in moiré reduction functionality, but neither one will be able to fully get rid of the worst moiré pattern occurrences.

Here is a comparison between the Nikon D800 and D800E (the latter is prone to moire), which clearly shows Moiré on the Nikon D800E (Image courtesy of Nikon):