2

I have this photo:

enter image description here

I want to remove all the "noise" that's introduced when taking a picture of a screen. For instance below is a zoom-in of part of the bigger image, from which I manually "cleaned" the annoying "noise":

enter image description here

How do I clean it automatically, or at least semi automatically (levels/curves/filters/etc...), avoiding the pointless tedious manual work in this digital age...?

  • 3
    So I gotta ask. Why not take a screenshot instead? – Joonas Apr 27 '17 at 14:28
  • Or take the image properly from start. – Rafael Apr 27 '17 at 16:09
  • Is that the original image, or has it been already altered? Looks too clean to be the original picture. – xenoid Apr 27 '17 at 16:14
  • @joonas This looks like a BIOS setup screen. No screenshot support at this point. – xenoid Apr 27 '17 at 16:15
  • A possible completely different solution: using a tripod, take several pictures of the same screen, minute moves of the camera should make the moirés different in each picture. Then load all the pictures as layer sin the same Gimp image, and put all layers in Lighten only mode. The GMIC plugin also has a "Median" filter that could work wonders. – xenoid Apr 27 '17 at 16:19
3

Taking a screen capture out of your BIOS

The BIOS you are using seems relatively modern. Now modern BIOSES typically can take screenshots! A bit depending on details what you usually do is:

  • you insert a USB drive on your computer.
  • hit F12, bit depending on model and make might be print screen of control f12 etc.

Now my second work computer has a similar HP setup screen as you and it can do screen captures this way (although I seem to remember that there was some extra trick to it). So i suggest doing it this way.

Capturing the data form your signal

It is also possible to capture the screen form the video signal itself. On a electronic level this is not really all that complicated since you don't need to capture more than one image. However, you probably don't have the hardware to do this available to you or at least not at hand when you need one.

If all else fails

Now if you really must take a picture out of a picture. And i really mean have exhausted all your other avenues because this iw actually a lot of work. Then you should:

  • Use a tripod, or at minimum brace your camera onto a object and use a timer to shoot the image.
  • Use manual exposure, metered form a neutral gray screen, if in any way possible.
  • Take test shots shots form different distances/zooms to get the position of the least amount of the moire effect. Then Adjust your exposure time so that you can capture one cycle.
  • Take multiple exposures and stack them on top of each other. Both Gimp and Photoshop have functions for image averaging, even discarding outlier pixels. IN PS this function is called a image stack
  • Straighten image

All in all the photography route is surprisingly time consuming. Also read:

5

It's not all noise. There's a heavy Moire pattern due the fact that you rasterized something already rasterized. One gets the same problem if he scans a printed photo. Digital signal prosessing mathematician would say that you have got a visible difference of the sampling frequencies both in the vertical direction and in the horizontal direction.

You should note that the pattern does not exist everywhere. That's caused by the lens distortion. There's a scaling differences between the areas of your image.

A precaution for future photos:

Take several photos at the same distance but having a little different zoom settings. Use a small aperture, for example 1:11 to keep the barrel distortion low. Also have a good tripod to be able to keep the ISO as low as possible for low real noise and no camera shaking blur.

If you want to fix your already taken photos, you can use some good noise eliminating program. The following example is the output from Neat Image (the 5 years old free version). The noise sample was taken from the dense pattern in the middle of the photo.

enter image description here

Unfortunately all faint buttont texts (Save, help, Exit) have nearly vanished. The remedy was to copy the cleaned image over the original as a new layer. Then the nearly vanished parts were erased from the cleaned version.

The cleaned layer got finally the level adjustment which was suggested in earlier answers. Now it works because the unwanted moire pattern remnants really are lighter than the wanted texts and shapes. See a screenshot of that final step.

enter image description here

I don't believe you can do much better by thislike simple methods except by redrawing.

3

My (probably unpopular) solution would be to take actual screenshots, not photos.

Or....

Rebuild the image. It's just text and rudimentary shapes.

Just 5 minutes work....

enter image description here

If overall quality is a concern, rebuilding the image would offer the best solution as well as ultimately being more versatile. However, I realize if there are multiple images it may be time consuming (but worth it).

Then, of course there may be other solutions I would also suspect since this is a product usage image, the manufacturer must offer a users manual contain images which could most likely be harvested.

In short, don't work with garbage if you know there are alternatives. Nothing you do to that photo itself is going to achieve optimum quality. The best you can hope for is probably "good enough."

0

Try Levels. Hit Ctrl+L and play with the markers circled in red. Push the second and the third markers to the left until it looks right. Depending on the result of this, you may also have to use the Eraser brush (E) to clean up the remaining noise.

enter image description here

  • Tried that. This photo is after one pass of levels - that's the best I could get. Anyway, levels and co. to my understanding will never eliminate the noise - there's need for some kind of "smart selection" filter that takes a local group of pixels and outputs single color. I think... – Tar Apr 27 '17 at 12:09
-2

I use Topaz DeNoise 6 filter. Does everything with no problem just by using a few sliders.

  • 3
    Consider to insert a screenshot of what can be achieved by using only that plugin. Use it to questioner's screenshot. All other will catch downvotes. Let that screenshot have also the settings. At least I am interested. Topaz stuff have premium price but the few pieces I have, also give something. – user287001 Apr 29 '17 at 12:55

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.