Processing Your Image

Coin Photography – Processing Your Image

There are eleven pages about photographing coins:

Black Background — White Background — Photographing the Edges — Using Extension Tubes — Choosing the Best ISO Setting — Choosing the Best Aperture — Choosing the Best Exposure — Editing the Background — Keeping Detail in the Highlights — Processing Your Image (this page) — Some Final Tweaks

evelling and Desaturating

Having taken a photograph of a coin and made the background whatever you want, there will still be a few more steps you might want to take. How far you go with this is entirely up to you. There are those who say that you should not make any more alterations to the image, but in my own view it is useful to bring the image closer to the way the coin actually looks, if that it possible. And, of course, you might want to use the photo as something other than a plain record.

Screen capture of a typical levels adjustment. First, you might think that the photo looks a little washed out. The tones in the picture don't cover the whole range from black to white. This can be fixed by tweaking the levels adjustment slightly, bringing in the end markers. Don't take them too far. A little will work better than a lot. You can also use this to lighten or darken the image if you wish, and if one side needs to be lightened more than the other, apply a gradient to the resulting levels layer. If you have combined obverse and reverse into a single image, you might need to adjust levels separately for each, before you merge the layers.

This is better, but in the process of making the picture less washed out, the colours have become artificially overemphasised. The earthy deposit isn't quite that vivid in real life. Adjust this by reducing the saturation slightly. In the example, this has been overdone a little, to show quite clearly what the effect of desaturation looks like. Click on the image to see how it really ended up.

ringing Detail from the Shadows

With a good image to start with, this will be all you need. This is the point at which you should bring back the detail you saved in your highlighted areas, as shown above. In some cases, you might also want to bring out some detail in areas that seem too dark, even black, to the eye. To do this, start with pure black "paint" selected. You might then try adding some of the darkest tones to the selection by using the "color range" dropper labelled +. Only select tones from the very darkest areas if you do this – usually it won't be needed. Then, feather the selection using select / feather. About 5% to 10% of feathering works for me. Then, with image / adjustments / levels, move the right-hand slider over to the left a little; never more than halfway. This will lighten the pixels that have been selected, and leave the rest alone.

If this works well, it will bring out more details of the coin. It can't bring back detail that isn't there at all, though. Be careful to keep the effect subtle. If it doesn't seem very obvious in the example shown, it was very clear what was happening as the slider was moved, and it does make a big difference to the overall effect.

The tweaks on this page should all be applied with care, but this one has a particularly powerful ability to mess up your image by making it look patchy, or alternatively, dull and lifeless. So check out the overall effect carefully before you move on.

harpening - The Devil's Footprint?

When you are happy that the image is right, you can resize the image to whatever size you have standardised on for your coin images. As a last step, my own preference is then to sharpen the image a little using unsharp mask. It's easy to overdo it (as usual), but I find that a small adjustment will compensate for the fact that my camera produces images that are slightly less sharp than real life. Be careful not to make the image unrealistic if it is for academic study purposes or to illustrate a piece for sale. But if the images are for your own enjoyment or for use as art, then clearly this does not apply.

Reducing the size of an image has a sharpening effect, so make it the size you want first. I get good results from Photoshop with "Threshold" set to 3, "Radius" set to 3.8, and "Amount" somewhere between 10 and 30.

There are eleven pages about photographing coins:

The content of this page was last updated on 27 January 2011