Cleaning up a Bitmap image...what are my options?

[Devon Burkhalter]

I have a bunch of historical documents that were scanned as bitmaps, and saved to a PDF. The text is fuzzy, and the client has asked me to clean them up. If this was grayscale, I'd be able to, but does anyone have a great workaround for cleaning up Bitmap images? I've tried Levels, Curves, Auto Contrast, Sharpening...which would all work to some degree if the document were anything BUT bitmap. What am I missing?!

Thanks, geniuses.

[c.pfaffenbichler]

You need to convert them to grayscale to apply any (Smart) Filters (in this case maybe Dust&Scratches), then you should (in my opinion) save those layered Files and save bitmap copies off them.

But as always: Garbage in, garbage out.

[Devon Burkhalter]

Thanks. I forgot to mention that I had converted them to grayscale to work with them. It's just that with bitmap, it's already either black or white...so nothing is really changing that much!

[c.pfaffenbichler]

So you need to use a meaningful Filter like Dust&Scratches.

so nothing is really changing that much!

For the Adjustments you mentioned probably »not al all«, don’t forget to view the results at View > 100%.

[Derek Cross]

Might be better to consider re-scanning using OCR, you will then have proper searchable, useable, readable digital text.

[c.pfaffenbichler]

No argument there, but as the OP mentioned

historical documents that were scanned as bitmaps

I suspect the actual pages might not be at their disposal at all.

[Devon Burkhalter]

I wish that were an option! These are historic documents (some from the 1800s). I'm not even sure the originals exist anymore!

[Derek Cross]

If it's worth it, it might be worth experimenting to see if this text can be digitised into live text.

[Devon Burkhalter]

Great idea, but these are legal, historical documents, so they really can't be changed in any meaningful way (just cleaned up, etc.).

[Derek Cross]

The best combination – if you have the resources – is to have the rasterised image so users can see the original image design and OCR text that's readable and searchable.

[edgrimley · Accepted solution]

Blurred first then used  Unsharp Mask. Better but far from good.

[Devon Burkhalter]

This is the best I've found as well. Yours is a bit better than mine with that method. Do you remember what your settings were?

[c.pfaffenbichler]

As I mentioned earlier: Garbage in, garbage out.

[edgrimley]

I think Gaussian blur was around 6.5, then about 500% and 14 pixel radius for sharpening. Make the layer a smart object first, then you can tweak them as needed.

[Devon Burkhalter]

Thank you so much, edgrimley. This will definitely work.

[Kukurykus]

There is similar topic in Photoshop Scripting section. That won't give you what you want, but I see it is somehow related as was made to clean old documents. Last version of script is not posted as a whole but in 3 parts, so do not think that correct solution have everything there should be. If later someone wants to have a script as a whole let me know so I post it in one piece: How to remove small black dots from text page - selecting pixel radius via script