Enhance Handwriting in low-light, low-contrast images

[Colin Walls]

I am sure that there are some specialised techniques and this is a good place to look for them.

Apart from the obvious tools to adjust contrast [like Levels], you may want to try copying the layer and trying different blending modes on the copy.

[Aonghus]

Thanks Colin. I should have added that one of the problems is that because of the low light and because I cannot use a tripod there is inevitably a slight camera shake which blurs the handwriting. My present method is to a) Desaturate b) Use Curves or Levels to increase brightness and contrast c) Use Unsharp Mask to sharpen.

The results are okay but not as legible as a direct photocopy from the machine.

Aonghus.

[Lundberg02]

What speed film are you using if you have to expose for a tenth of a second? Why not use ASA 1000 or 4000 or something suited to the problem? You don't care about grain do you ?

[Michael B. Field]

also if you have access to a dupe machine you could rig it with black and white film, some extensions to compensate for the microfilm size and you wouldn't have to worry about camera shake. I don't see why you can't use a tripodand rig that up somehow but the camera shake is probably the biggest problem. Maybe a high speed graphics film would work also..ortho or something of similar contrast. I don't think the problem is with photoshop but with the technique you are using to copy the microfilm.

[Burton Ogden]

Aonghus,

I agree with Michael that you should use a tripod and you should be able to use a tripod. A reasonably versatile tripod and tripod head can position your camera any way that you can. You may need an extension arm if you are shooting straight down and you can't straddle the subject with your tripod legs.

But if for some reason you can't use a tripod, Lundberg's suggestion to use faster film seems like a good approach. That presumes you are using a film camera and not a digital camera. You didn't say.

If you are using a film camera, then you must be scanning the photoprints or negatives into Photoshop, but you also didn't mention anything about your scanner. For low contrast images you should scan at higher than 8-bit RGB. Depending on your scanner you could be scanning 30, 32, on up to 48 bits of RGB resolution, all of which will come into Photoshop as 16-bit per channel RGB images. The higher precision images allow higher precision Photoshop adjustments in brightness and contrast, which you need to "tease out" a decent image from a low contrast, underexposed image. After you get a decent adjustment you can "downshift" your image to the 8-bit RGB image mode to apply filters and other tools that aren't available for 16-bit mode images.

If your images are unavoidably blurred or out of focus you could try the demo of the Focus Magic plugin for Photoshop. I use it and like it because it sharpens the entire image and not just the edges. For more information on Focus Magic and a free download, see:

<http://www.focusmagic.com>

-- Burton -- (not associated with Focus Magic)

[Aonghus]

Many thanks for all the suggestions. They were both practical and helped me examine my approach.

BTW I can't use a tripod because I'm usually doing it in public libraries where they are generally forbidden. I use a digital camera because they are silent and unobtrusive. Some of the places I shoot forbid all cameras - I have to be discrete ...and lucky.

Thanks for the suggestions on improving contrast and legibility. The problem of shake I am now tackling by reducing the image size on the microfilm reader so I can get both elbows on the table! I have bought FocusMagic and it really helps. It was created to improve omnidirectional blur but they promise another version for directional blur which will really help camera shake. FocusMagic is the best filter "sharpener" I have found.

Aonghus.

[YrbkMgr]

Sounds illegal as hell to me...

[DOMTEK]

$#&X@!! I feel a bit used