tiny white specks in scanned b/w

I've been copying some old b/w family photos, and some are less than perfect of course. Sometimes I don't get much shadow detail and sometimes none at all. These areas of black print quite solid but often contain numerous tiny white specks - and I don't mean dust. I can control them to some extent by increasing the black.

What causes these specks? What should I do to prevent them?

TIA!

Paul

Flatbed scans of prints?

Take a look at the glass of your scanner with a powerful torch - mine spattered grease from the head drive mechanism all over the inside of the glass.

The result was tiny white specks (actually reflections), most noticeable in dark areas.

With old film prints and negatives, there is always a substantial likelihood that the 'specks' are in the original -- as it came back from the processor (especially drug-store processing).

"Spotting" was a necessary and vital skill in working with prints from small to medium negative: Many photomagazine articles and ads for brushes and inks.

Here is an unretouched image from my very first roll of 35mm Plus-X (I think) as processed and printed by the camera store where I bought the camera:

There are lots of scratches and spots that don't show in this small image....

Thanks to you both!

Steve - Somehow the spots didn't strike me as grease spots. Haven't used my scanner for years, and my "stars" vary with the darkness of the black background. Nice try!

JDM - The spots I'm talking about are quite even, in size and in spacing. Haven't done much traditional photography lately. But the digital spots I'm talking about are easy to conquer with a Photoshop "spotting brush"... it sure would be easy except that they're so numerous!

The closest I can think of is a starry sky on a clear black night with a multitude of stars.

Whatever ... thanks to the two of you!

Paul

The spots I'm talking about are quite even, in size and in spacing ... The closest I can think of is a starry sky on a clear black night with a multitude of stars.

There may be another explanation for the white specks on your scans. Do they look like individual pixels or clusters of pixels, not randomly shaped dust spots? If so, they may be caused by a programming bug in your scanner software or image editor.

In my case, some scanned or DSLR-copied images have black specks. Usually they are individual pixels, resembling sprinkled pepper. In extreme cases, they are clusters of black pixels.

Upon further investigation, I discovered that the black specks don't appear in my raw scans or copies. They appear when I edit the image in my old version of Adobe Photoshop. The "auto levels" command (which remaps the histogram) often does it. The black specks always appear in areas of blown-out highlights. Sometimes when scanning or copying a faded photograph, I must overexpose a few highlights to recover detail in the dark areas.

I think I know what's happening. Pixel values have a numeric range: 0 to 255 per color channel in a 24-bit image (such as JPEG), and 0 to 65,535 per channel in a 48-bit image (such as a RAW file after importing into Photoshop). Black = 0, white = the maximum number. When "auto levels" or another command remaps the histogram, a blown-out highlight may exceed the maximum. In that case, the program should limit the pixel value to the maximum. But if it allows the pixel value to "wrap around" to zero, the white pixel turns black.

In your case, maybe the opposite is happening: pixels in dark areas are wrapping around from zero to the maximum value per channel, so they are white.

Although these false pixels can be manually erased, it's time consuming if they are numerous. One solution is to use Photoshop's noise-reduction filter set to a radius of one pixel. It works but slightly blurs the film grain.

Another solution is to use an image editor that doesn't have this bug.

Randomly distributed white spots in scans of old prints are very common. In many cases, you can see the flaws in the original photos if you look closely enough, but magnifying them on the computer screen makes them more apparent.

I've been doing some restorations recently, and this is one of the major chores. One suggestion is not to get too carried away by what you see when you blow the image up. What matters is the spots you can see when you display or print at the intended size.

There is a technique for removing lots of these at once without using the clone or healing brush. It doesn't always work, and you have to be prepared to tinker with it, but when it works, it saves a huge amount of tedious work. You can find the original description here: Quickly Remove Many Small Spots/Speckles Without Healing Brush or Clone Stamp - Robert Bryll (robertb). My slightly modified procedure is this:

1. Create a duplicate of the background layer. This layer will be used solely to produce the mask
   
2. Select the duplicate layer. I’ll call this min/max. Use the minimize filter to eliminate spots, setting the pixel width as small as you can. Then use the maximize filter with the same pixel setting. 1 px is often sufficient..
   
3. Set the blend mode of min/max to difference.
   
4. Select the first two layers and create a composite, alt-ctrl-shift E or the mac equivalent. Label the resulting layer Mask.
   
5. Clip a levels adjustment to Mask and brighten and expand the white spots.
   
6. Select Mask and the levels adjustment and create another composite. Call this Mask 2.
    
   
7. Create another copy of the background layer, label it blur, and move it to the top of the stack.
   
8. Turn off everything but the background layer and Blur.
   
9. Add a mask to blur, and copy Mask 2 to the mask on this layer.
   

Without seeing an example of the spots, it's all guesswork.

My guess is that the spots are reflections from the surface texture of the prints. In which case you might have better luck copying the prints with a digital camera, whereby you can control the lighting. Not so with the moving strip light in a scanner.

Here's an example of the difference between a flatbed copy of a slightly wrinkled print, and a camera copy; using two lights at about 45 degrees to illuminate the original B&W print for the camera.

1st a crop of the flatbed scan -

And the same area of the camera copy -

No afterwork was done to either copy BTW.