6

I am almost ready to launch an e-commerce site for a client but some of the clothing images have a strong moiré that is quite disturbing:

moiré effect on dress cloth

I know I could blur the photos to get rid of the moiré but:

A) because of the number of photos involved, that will be a huge amount of work and

B) we will lose the clarity of the photos on screens where the moiré is not a problem.

Is there any way to deal with this problem without systematically degrading the images?

[edited: here is a low-quality close-up of the original photo]

degraded version of original photo, for texture

  • I see in your photo strong moire-like patterns, but they are not dependent on screens in this house where I live. Should the orange cloth look out smooth? Or is a part of the patterns not the moire that you want to get rid of, but a part of the canvas texture or in-canvas multi-layer moire? Can you possible specify which patterns are wanted and which are unwanted? The perfect smoothening is more easy in Photoshop by low pass filtering than by blurring. Unfortunately the LP-filtering needs a trick, it's not directly selectable, but that trick can in your case probably be an action. – user287001 Aug 9 '17 at 0:31
  • I didn't post the original, I posted a screenshot with the moiré. The original shows the cloth texture nicely (on hi-res screens). I would like to keep the cloth texture in the photo. I'll add a close-up to the question. – Andrew Swift Aug 9 '17 at 6:16
  • Can you post one of the originals at full size? – Ryan Aug 9 '17 at 12:37
  • The photo above (some cloth and some hand) is part of a full-size original. The quality was diminished by imgur but it's at full resolution. – Andrew Swift Aug 9 '17 at 16:22
  • 1
    At least post a bigger sample of the original resolution where the moiré is more visible, so people can test diferent methods. – Rafael Aug 10 '17 at 16:13
0

I rewrote the answer due the new information.

The problem was not some ultra-fine canvas texture interfering with ultra-high resolution displays or the camera, but the very well visible colored lines in the canvas. I have marked with blue some of the problematic lines in your screenshot:

enter image description here

These lines cause no problems with your 1600 pixels high display, but interfere heavily with your customer's screen which is only 800 pixels high.

You have following options:

  1. Let it be (probably actually not an option, because your customer can see it as your mistake)

  2. Low-pass filter the image. That unfortunately makes the canvas plastic-like.

Here a heavy filtering is applied to your heavy-moire screenshot only to show, what kind of plasticity I mean:

enter image description here

I will insert the practical methods for the low-pass filtering to the end of my answer.

  1. If you resample the image to a little different pixel dimensions, the moire pattern can be less noticeble

  2. The website can have a possiblity to show different images for different display resolutions. So the big screen owners can see crisper images, the filtered one is for low-res.

How to low-pass filter:

Photoshop's Smart blur is quite optimal for this purpose. It's made for hiding faint details, but saves strong borders. The gaussian blur would need much more tinkering.

  • select the cloth area. This case is easy with the quick selection tool
  • goto Filter > Blur > Smart Blur and play with the controls

enter image description here

Another practical method is to use some noise sample based noise reduction plugin or stand-alone program. You can show by making a selection which is the unwanted noise pattern. Camera noise model based programs can be unuseful for this.

My filtering example was done with old Neat Image. It was applied twice. I hadn't it as a plugin, so the model was filtered too. The model was restored by cutting and pasting her onto the filtered image.

Both methods gave virtually the same result.

The third way is to subtract a high-pass filterd version, but it's very tricky, because strong borders must be added back and the lost color must be restored. => 1000% more work, mostly with layers and blending modes. The method allows plenty of control, but it's not practical.

  • The moiré is not in the photo (only the cloth texture is there). It is visible on lower-resolution screens (1280x800) not on high-res screens (2560x1600). The moiré is caused by the texture of the cloth, visible in the closeup of the cloth, interacting with the pixels of the 1280x800px screen. I will experiment with low-pass filtering. – Andrew Swift Aug 9 '17 at 14:35
  • The answer is "yes, it's the blue lines that are the problem and I am out of luck." – Andrew Swift Aug 9 '17 at 16:23
1

In a word, no.

Moire is an artifact of the interaction of your raster-display and the fabric pattern. Defocus is the way it is normally diminished or to change the pattern angle to something like an oblique screen-print angle. If the photos have been already prepared, there's not much more you can do.

If you cut in a close-up "magnified view" for the texture detail and colour, you might get away with the defocus for the overall product beauty shot for problem moire product renderings.

  • Moire is ringing, and anti anti-aliasing is a trade of between ringing and blurring. So technically one could blur the image, either by out of focus or in post. Which would make it less sharper but less ringing. Or one could use a camera with more resolution. Or one could usa a camera with aa filters (which are less sharp but dont ring) – joojaa Aug 7 '17 at 18:30
  • Thanks for the information. The moiré is caused by an interaction between the site photo and the client's (non-retina) screen. It's not present in the original photo. It looks like my only option is something like Select Color Range » Gaussian Blur in Photoshop. – Andrew Swift Aug 7 '17 at 21:48
  • @joojaa postshot blur is not equivalent with aa filtering. Postshot blurring is useless if the alias frequency happens to cover something essential of the image spectrum. Imagine the canvas pattern to be in the photo nearly as dense as image pixels. – user287001 Aug 9 '17 at 1:34
  • It is if you drop image size at the same time. But yes not as efficient as analog aa. But i said technically. – joojaa Aug 9 '17 at 3:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.