Cleaning up old blueprint scans

[wcbennett3]

Hi everyone,

I have a question about cleaning up a scan of an old blueprint. These prints are almost 100 years old and I am working on some artwork for a renovation project. The scans can be found here and here (sorry for the links - the files were too big). I would like to clean one of these up enough in Photoshop to save it, place it in Illustrator, and effectively use LiveTrace. I have not been able to clean the scan up enough to do this, though. Can anyone walk me through this?

Thanks,

~wb

 

[Tom Mann]

The problem is that the scans were not done appropriately to be able to post process them. Once they have such high contrast, it is almost impossible for other software to determine what is a real feature and what is noise. Such high contrast, even thresholding, is fine for viewing by humans and is common with engineering and architectural drawings, but makes further processing very difficult. These should have been scanned like they were contone photos, not line drawings.

If if the originals can't be re-scanned, I'm afraid that you have a lot of tedious manual work ahead of you.

Tom M

 

[revnart]

The one image I've opened is in Bitmap mode. Second link isn't working.
Whole image is made only by pure black or pure white pixels without any shades of gray, so as Tom already pointed scans should be taken once again without such high contrast.
With those images you can use magic wand and select all black pixels, then Select>modify>contract by 1px, then inverse the selection and fill it with white, this will get rid of those random black pixels but unfortunately this way you will also lose some data.
Different approach that comes in my head is to gaussian blur it by 0,5 several times, and then use levels to increase contrast.
I guess not any of this idea "cleans" that scan ideally, I guess its rather must be done by hand.

 

[Tom Mann]

Although PS doesn't provide morphological operators (... Google the Wikipedia article on these), they can be very useful for this sort of "clean-up" work, other, more mathematical image software does. Google {morphological operators Matlab}.

Revnart's suggestions approximate some of these operators in PS.

Tom M

 

[chrisdesign]

I gave it a try, but it is impossible to get a good result.
This is done with TOPAZ Clean.

 

[Tom Mann]

Oh, BTW, I forgot to mention that to be able to distinguish real features from imperfections, the scan should not only be done as if this was a continuous tone photograph, it should also be done at a surprisingly high resolution (eg, more than sufficient to see the texture of the original paper), and the scan should be done in color. The latter is so that slight differences in color, not just luminosity, between the ink and imperfections can be used to pull out the real features. This follows both the general philosophy and specific techniques for image restoration as stated by Ctein in his classic book: http://www.amazon.com/Digital-Restoration-Start-Finish-photographs/dp/0240808142/ref=asap_bc?ie=UTF8.

Little could be done with the scan reproduced here because it is (a) much too low resolution, (b) the scanner had feed mechanism problems (viz, the parallel vertical lines towards the LH edge of the scan), as well as (c) appears to have been thresholded.

Tom M

 

[wcbennett3]

Thanks, Tom. I'm traveling, but I brought the originals with me and had them rescanned as contone photos at high res. I'll let you know if it works.

~wb

The problem is that the scans were not done appropriately to be able to post process them. Once they have such high contrast, it is almost impossible for other software to determine what is a real feature and what is noise. Such high contrast, even thresholding, is fine for viewing by humans and is common with engineering and architectural drawings, but makes further processing very difficult. These should have been scanned like they were contone photos, not line drawings.

If if the originals can't be re-scanned, I'm afraid that you have a lot of tedious manual work ahead of you.

Tom M

 

[wcbennett3]

Thanks! That's closer than I got - hoping the new scans work better.

I gave it a try, but it is impossible to get a good result.
This is done with TOPAZ Clean.

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