Photographing art behind glass

A couple of weekends ago, prompted by the Waldo Canyon fire, we catalogued and photographed all the maps, art, and photographs we have hanging on our walls. Just in case there’s another disaster when, somehow, we’re not quite as lucky as we were with the fire, and have to claim for them all from the insurance.

Problem is, if you photograph something that’s behind glass straight on, you get a reflection of you, the photographer, in the picture. There are various techniques you can use – such as photographing from behind a black curtain, with the camera poking through, or strategically arranging a set of lights to illuminate the object but not the photographer – but after some surfing I’ve found a really simple technique using Adobe Photoshop (I’m using CS5, but I don’t know when this particular feature made it into Photoshop).

First of all you photograph the object from a shallow angle (not quite straight on):

Southwark 1766 (original photo)

The great thing about this is that the camera is no longer reflected in the glass, although the image you take will be a trapezium. Make sure that two sides are parallel (it helps later on). I also make sure that what is reflected in the glass (something will be) is a neutrally-colored ceiling or wall. Then you open up the resulting trapezoid image in Photoshop.

Select the crop tool. Now, by default, clicking on the image and dragging the mouse produces a rectangular crop area:

Image with rectangular crop

The interesting thing is that the four corners are draggable independently. So, drag them to the four corners of the trapezoidal image:

Image with adjusted crop

Take your time over this. I’ve found that zooming the image really helps at this stage, and the more exact you are, the better the result will be. Now, when you accept the crop, Photoshop will reformat the cropped area as a perfect rectangle and will adjust the image accordingly. Here’s the resulting image, with color, contrast and exposure adjusted as well:

Proposed Southwark through roads 1766

(Click on it to see the detail.)

A couple of points are worth mentioning.

With a little practice (and that’s all I had for this example), you can get some excellent results. For interest, I superimposed the Google maps version of the same area over this de-skewed image:

Southwark 1766 superimposed with modern map

This shows quite impressively how accurate the de-skewing crop feature is in Photoshop (and also incidentally how accurate the mapmakers were in 1766). I also used the same technique to produce the image of my first Volvo 1800S in this post (the page from the calendar was framed some 20 years ago).

Album cover for Glittering Prize: Simple Minds 81/92Now playing:
Simple Minds - Waterfront
(from Glittering Prize: Simple Minds 81/92)

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2 Responses

#1 Schalk Versteeg said...
16-Jul-12 10:44 PM

Hi Julian,

If the insurers in the states are anything like those here in South Africa, images won't be good enough. Ours insisted on either proof of ownership via invoice (original boxes where not good enough) or for valuables like art, collectables and jewelery they insisted on proper validation certificates.

#2 Jeroen Pluimers said...
29-Jul-12 6:33 AM

Two other great tips taking pictures through glass:

  • use a polaroid filter

  • make sure your camera is against a dark background

The filter gets rid of a lot of reflection.

The dark background too.

The same tips apply when photographing things through a liquid surface.

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