There are some techniques within PS that can be used and some not available from within PS (or to the public yet).
First some info on best B&W image reconstruction of half tone newspaper print image that uses vary size dots.
Note that there is more information in the half tone image then most scans are set up to capture. When viewing half tone image using varying dot sizes, the human eye if viewing from a sufficiently large distance will integrate the “areas” of black with the “areas” of white to create the perception of a gray scale. To accurately reconstruct this same tone, one needs to have a scan where the areas are measured. Thought his can be considered overkill, scanning where the smallest pixel size of the scan is 1/2 the size to he smallest dot in the half tone image. From a practical distance the pile size should be about 1/10 the size of the distance between the dot centers (you can get by with 1/5 through not quite as good).
This is different from using an FFT. FFT works best for repeated identical patterns such as the regular stipple pattern such one can find in some matte prints or bad scans with patterns causing Moiré. FFT could be used in addition to the above technique and possible provide an even better result.
The scan should be done in grayscale or RGB (not bitmap), TIFF (not JPEG), and at the above mentioned resolution.
Without going into the math, then:
- Turn the gray tone/ RGB image into a Smart Object
- Apply the box blur filter and then slowly increase the input number from the minimum value of 1 until the pattern has just been eliminate (any higher and you just increase the blur.
Note that the above technique does not increase the resolution that is lost during half tonne, just more accurately recreates the gray tone levels and eliminating the annoying half tone pattern.
The GIF below is an example of the above workflow applied to a old newspaper article about my Great Grandmother. I only am showing the lamp on the table in the overall image since it had some details. It is a ceramic ball with some leaves and a rose on it (I have seen it in person ages ago). I was quite surprised at how much detail (or perceived detail) that could be recovered using this approach:
Click on image if you do not see animation.
Now if you have a bitmap or JPEG at much lower resolution, you can’t get as good a recovery yet you can still try out the same technique.
In the OPs image, I upsized by 500% (my machine did not have enough memory to go to 1000% or 10X) using the “Nearest Neighbor” interpolation algorithm when resampling (important!). Then you apply the box blur image.
To demonstrate this approach, I have zoomed in to the Ops image to a chimney in the far background marked by the blue arrow in this image
To show the the impacts of this approach I also included a GIF animation below cycling among the original image, eggy’s approach (very good) and the approach I documented above (maybe slightly better).
Click on image if you do not see animation.
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Now that was the inside PS approach.
There are also some approaches that are very compute intensive and will probably not be adopted by Adobe given the average computers limitations.
Though not available to the public (yet), there were some NSA image algorithms being made available (indirectly) to research Universities. First stage is sending in the image for processing and the intermediate passes are provided back to the University. Full algorithm disclosure is to be released select Universities in the future. This program is headed at the NSA by Bob Smith and the technique is called Super Pass Object Oriented Fourier Transform (BS-SPOOFT). (I suspect this is some 3D version of the fast Fourier transform but what the heck do I know)
My son is a recently graduated PhD student at Rice University (Houston) and brought these NSA algorithms to my attention. Though I could not get direct access, I forwarded the OPs image and a very small section was processed through the multiple pass BS-SPOOFT.
I took the passes and overlaid them on the original image as a GIF sequence as supplemental frames in the prior GIF animation.
Note that this chimney “is” the chimney in the original image.
Click on image if you do not see animation.
What do you think of that? I think it is incredible and almost seems too good to be true.
Well it was. What I really did was locate the exact location of the original image in google maps with the position on the street the same as the angle of the original image. It's a specific spot in Frodsham UK pointing almost due east. Here is a link to a zoomed in view of the chimney in Frodsham, UK (
http://tinyurl.com/oymg2fy)I screen shot the picture and found a spot on the google maps shot that was unencumbered by the growth of trees and changes over decades of time and one of the chimneys was a perfect match (Told you it was the same chimney as in the OPs image. The rest is PS magic. Say, what can I say. Bob Smith was simply “BS” and the algorithm was just spoofed (“SPOOFT”). Sorry about that, yet the "in PS" approach is valid and I use it all the time. Everything else was just for grins. Thought it was time to add a little humor and hope no one takes offense for the short side diversion. You just never know who you can trust do do you?
