Tintype photographs are the easiest type of antique photograph to identify. Despite what the name suggests, the substrate was usually a thin sheet of iron. The tintype process was patented in 1856 by Hamilton Smith and as the photo below shows, the tintype process was still being used at the turn of the century. Dating the clothing in the photo puts this image’s date around 1900 to 1905.
A tintype is a very underexposed negative that is on top of a black varnish finish. Because it’s a negative, the areas of the image that recorded shadows are clearer and show more of the black background. Conversely, the areas of the image that recorded highlights have more silver and show less of the black background. But since silver isn’t as bright as the white paper we’re used to seeing as a film substrate, tintype images tend to be dark and they don’t have a lot of contrast.
Therefore, when making digital copies and restorations of tintypes, the most important step of the process is getting a good scan of the original. This is one case where you do not want to use your scanner’s default settings. Doing so will get you an image that looks exactly like what your eyes see.
Instead, we want to look at the scanner’s preview image and set the histogram so that the black point is the darkest part of the image and the white point is the lightest. For most tintypes, this means you’re going to be using less than half of the contrast range your scanner provides. Because of that, it’s important to use the highest bit depth your scanner offers.
For example, if your scanner has 16 bit scanning depth, it can record 65,536 levels of gray. But due to the lack of any light grays and whites in a tintype, the values in a tintype will only use the lower range of that 65,536. So we may only be left with 20 or 30 thousand values to work with. It’s important to get as many values as you can in the scanning step so that when you get to the Photoshop work later, you have the most amount of information to work with.
When the image is scanned those 30,000 levels are going to be spread out over the full range of 65,536 levels. So all along the range there will be holes. If those holes are too big, you’ll notice definite steps in gradations of gray levels.
In the image shown here, there were numerous spots and scratches, way too many to fix by with the clone brush or the healing brush. Photoshop has a Dust and Scratches filter you works quickly, but it works by blurring the image. Since tintypes are usually pretty soft to begin with due to the technology of lenses back then and the small size of most images, it’s not desirable to make them even softer. What I did with this image was to duplicate the image on a new layer, use Dust and Scratches on the duplicate layer, and then set that layer to darken. That way the only pixels that were affected were the missing pixels.
That fixed about 80% of the problems with this image. After that I used the healing brush and the clone brush to fix a few other areas.
The final step was adding a Contrast adjustment layer with a slight S curve, just to deepen the shadows a bit.