Removing a textured pattern from a scanned photo ? 5 minute digital fix
One of the most common problems when dealing with scanned photographs as part of a digital restoration activity is that after scanning, the digital image appears to have a textured pattern to it.
This is often caused by the fact that the photograph in question has been printed on textured photographic paper.
This article will show you how to remove the un-desirable pattern effect without significantly loosing any of the important image detail.
The problematic photo may well be an old black and white, sepia, or even a more modern colour photograph.
(I remember Kodak introducing their "Silk finish" prints many years ago printed on a silky sheen textured paper!).
The example image on our web-site is an old black and white wedding photograph that has been printed on a textured paper.
If you look closely at the white cornice behind the bride and groom you can clearly see that the textured pattern of the photographic paper has been faithfully re-produced during the scanning of the photo.
Before we commence any major restoration work we would like to remove as much of the un-desirable textured pattern as is possible.
Step 1
Open the image up in Adobe Photoshop and the first step is to create a duplicate (copy) layer of the original image by selecting Layer-> Duplicate Layer .. and give the new layer an appropriate name.
Zoom in close enough to get an appreciation of how severe the textured pattern is, but keep some picture detail visible (especially people's faces) so that you can easily judge how well the texture removal is proceeding without loosing too much important picture detail.
Step 2
With the duplicate layer active apply a Gaussian Blur by selecting Filter->Blur->Gaussian Blur ...
A pop-up option box will allow you to set the amount of Gaussian blur to apply to the image.
I generally start with a Radius = 1.5 and work up from there, constantly looking at the image to see the affect as I increase the blur radius.
Anything over a Radius = 5.0 will usually be far too harsh, so in the example on the web-site the required outcome is to "minimise" the texture pattern effect without compromising the important detail in the photo.
For our web-site example image I found I was able to set Radius = 3.5 without any significant loss of detail.
The example image is starting to "soften", but the textured pattern has clearly diminished.
Step 3
Zooming out to have a look at the complete photo reveals that the un-desirable textured pattern has all but vanished with only minor softening of the important image detail.
Each photo you work on will have to be judged on its own merits when determining the amount of blur to apply.
But all is not lost on retaining that important image detail!!
Step 4
Remember ... the Gaussian blur has been applied to the duplicate layer we created at the start of the exercise.
The original image, complete with texture, is sitting under the duplicate layer.
By using Photoshop's Layer Blending Modes and Layer Opacity we can produce an image made up of a combination of both layers with some of the detail from the lower original layer showing through.
Again, each photo will be judged on its own merits and the setting I finalised on for our example image on the web-site may not be the same as you will find most suitable for your own images.
Try experimenting with the different blending modes and layer opacity settings.
I finally settled on a blending mode of "Luminosity" and Opacity of 85% for the Gaussian Blur layer.
Step 5
To finalise the image I then "flattened" the two layers into a single image layer by selecting Layer->Flatten Image.
Step 6
I then checked the tonal range of our combined layered image using the Levels command by selecting Image->Adjustment->Levels ... and fine tuned the black, white and grey points.
Step 7
And last but not least, we can still bring a little bit more "sharpness" out of the image by finally applying a small amount of Unsharp Mask by selecting Filter->Sharpen->Unsharp Mask ...
Experimenting with the various settings, I was able to settle upon Amount = 185%; Radius = 2.5 pixels; and Threshold = 50 levels.
And there you have it ... the removal of an un-desirable textured pattern without significantly sacrificing important image detail.
If you find the steps being taken are a little hard to understand in this text based article, you can click on the link at the end of this article to see the same method explained on our website with the aid of example graphical images.
© Gary Wilkinson 2005 - All Rights Reserved
You can see this method complete with example images at Removing a textured pattern from a scanned photo
Feel free to re-print this article provided that all hyperlinks and author biography are retained as-is.
Gary Wilkinson is a photographer, photographic restorer and the owner of a photographic retail business. He is also the publisher of the http://www.restoring-photos-made-easy.com website, where other methods of correcting common photographic restoration problems are discussed.
Article Source: Messaggiamo.Com
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