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I ran into a sticky editing challenge recently when editing up a wedding shoot. During an incredibly beautiful moment between the bride and groom, two layers of her veil material shifted across each other. While the series of shots were beautiful, the intersection of the fabric presented a challenge for the sensor in my camera. Yep…even a 5D MKII isn’t impervious to this maddening fabric effect…but I digress.

Here is a cropped shot of the very pronounced moire (pronounced moy-ray) pattern. This pattern occurs when the sensor creates a type of banding when trying to resolve the pattern in the fabric across it’s microscopic pixel sites. Most shots escape this challenge, but the few that don’t, create a bit of a retouching nightmare.

After doing some research online, I found that some of the fixes suggested on a few websites helped somewhat, but did not fix the problem convincingly. The shot was destined to be a large print, and a test print at 8 x 10 seemed to just amplify the problem. The stripes on the grooms cheek looked like ‘racing stripes’….yuck!  What to do?? Well…this was a bit of a challenge but the shot was definitely worth the time to retouch it.

For those who have encountered this image challenge, you already know that a simple cloning or adjustment layer doesn’t cut it.
Those types of fixes just make matters worse. I tried isolating the problem streaks in the various channels…again..making adjustments there just made more of a mess. I wrestled with the issue of retaining detail in the fabric without destroying the clean shading of the skin. I ended up combining several Photoshop techniques in what amounted to a somewhat-technical fix.
I think the result really speaks for itself though. The image now prints beautifully with an acceptable amount of fabric texture.  While some people might argue that the effect isn’t totally removed in certain areas of the shot, I opted to leave a bit of the effect in areas where the fix might do more harm than good. I would encourage you to make up your own mind as to the extent of what is ‘necessary’ in terms of the ‘fix’.
The fix took a bit of time, working in segments, but here’s what I ended up doing to effect the retouch.

First, create a selection of a portion of the image layer. I used the lasso tool (L) with a few pixel feather, to select one area at a time. Pressing Cmd-J (Control-J for Windows) puts the selection on its own layer.
This piece by piece approach allowed me to isolate and tweak each repaired section.  Since some areas of the repair required different degrees of blending to appear ’seamless’.

For this tutorial, let’s use this area of the grooms cheek.

After selecting the area with the lasso, press Command-J (Control-J for you Windows users) and you should now have this selection on a layer of it’s own.(Click on the “eye” icon on the Background layer to see this new top layer by itself).
Click back on the new layer to ensure the selection is what you’ll be applying the filter to.

I then applied a median filter. For the large 21 megapixel file I shot, a value of 17 pixels was used. The median filter has an ‘averaging effect’ which helped to balance the dark bands.

You can find the median filter under: Filter/Noise/Median.

Zoom in to 200-300% so you can see clearly what you need to fix. Click on the eyeball on your base layer to turn it’s visibility back on. Click again on your fix layer to re-select it for the next step.
Option-click (Alt-Click for Windows) on the layer mask button. This will fill the median filter layer with a black mask obscuring the median filter layer.

Set the layer blend mode to ‘Lighten’.

Select your Brush tool (B) and use a fairly soft brush. Set your brush opacity to around 30%. Press your D key to set your foreground and background colours to white and black. Paint with white paint on the mask to reveal the median filter adjustment in the areas where the moire ‘stripes’ occur. If you’re using a tablet and pen to retouch, this is considerably easier than using a mouse! Use careful strokes to reveal the adjustment made on the Median Filter “Fix” layer. If you overdo any areas, remember you can toggle the foreground/background colour by hitting your X key. Reset the colour to black to ‘hide’ any overdone changes. (When using masks, remember the pnemonic “white reveals, black conceals”).

You should end up with the following result…(I know it’s not looking good yet, but there are a few more steps…hang in there!)

Since the correction creates a bit of a smooth/posterized effect, the next step was to fill in the detail that the median filter blew away.

Create a new blank layer on top of the ‘fix’ layer. Rename the new layer to ‘Clone’. Here’s how…

Select your clone stamp tool (S) and set the mode to lighten and the opacity at approximately 40%.

Zoom in closer by pressing “Cmd +” (Cntrl +). Make sure you can see the detail that needs to be replaced.  Begin cloning the detail back into the areas which need it.
IMPORTANT: Make sure ‘Sample All Layers” is set and pay very close attention to your sample point! Make sure that you are cloning to extend the existing fabric detail into the gaps. A couple of mouse clicks/strokes with your pen will add the detail back in. You’re cloning the fabric detail from the base layer up onto this new layer and the fabric lines have to match as closely as possible. (Especially if this is to become a detailed hi-res print!)
This takes a while but it is an important step to create a convincing fix.

Clone from areas of detail to areas of low detail.

Toggle the cloning layer on and off by clicking on the eye in the layers palette to see how you’re doing and see if there is anything you missed. This will enable you to see the effect of your repair versus the previous step.
Working backwards and forwards by toggling the layer on and off helps your eye to pick out areas that still need attention.

You can see the marked improvement, but in this case, another cloning layer needs to be applied to add detail just to the right of center, about 1/3 of the way down from the top of this capture.
Depending on your image and the areas which need to have more detail reconstructed, you can add an extra cloning layer or two if you need to. The bottom line is…does the fabric have its natural continuity of lines?
Use your judgement on this point. I decided to add another cloning layer to improve the detail.

The last step was to adjust the luminosity of the repaired areas. With the detail restored, a curves layer set to boost luminosity was the ticket.

Here’s the screen shots and description following…

Create a new curves layer by clicking on the new curves layer button.

Drag the curve upward slightly to create a lightening effect. Set the layer blend mode to luminosity. This setting is to avoid any unintended colour shifts or changes in saturation due to the boosted curve. Option-Delete (Alt-Backspace? for Windows..sorry?) on the layer mask button to fill a new mask with black. If your colours have been reversed don’t forget to toggle the foreground and background with the X key.
Like when we revealed the median filter layer in the previous step above, now you use a larger, soft-edged brush to paint with white on the mask. (Use a setting of 7-10% and build the lightening effect over a few strokes). Toggle the layer on and off to see the effect of the repair.

Here is the cheek before and after the luminosity curve adjustment:

You can adjust the opacity of the layer if needed to blend your curves layer perfectly. In the above case, the luminosity curve layer was reduced to an opacity of 62% to allow for a better blended match.
As with the cloning layer, you can add additional luminosity curves to carefully tweak your results…it’s up to you to determine how fine you want to make the adjustments. The principle of this type of correction is what I want to communicate here.
To be clear, I sometimes ended up using two cloning or luminosity layers for each repair section, but not always. If you can make use of the idea of a median filter, detail recovery, and then subtle luminosity tweaks…you’ve got the gist of the fix.

Here’s the final shot with the original for comparison…note how convincing the fix is overall.

Before and After Comparison of Moire Fix

I realize that some might point out that there is still some moire in a few spots, but I think the fix over the faces, large patches of lapel, arms, and hair were the most important spots to address.
I also realize that there is still a remnant of the pattern over the brides eye and nose if you look really closely. To undo the pattern here meant messing with too much fine detail.
I’m happy to report that the file prints beautifully and quite large to boot, with no pattern pulling us away from the beautiful moment.

Hope this tutorial helps out in some way! (It’s my first so go easy on me…please!)
Work in small sections, use your median filter and your clone tool, use your luminosity masks to make final tweaks… and you’ll have a happy couple with a shot they can cherish for years to come.

Cheers,

Peter