A Tip for Straightening Skewed Photos of Paintings

A Tip for Straightening Skewed Photos of Paintings

Postby CAP » Sat Aug 30, 2014 12:58 pm

A persistent problem photographing my own paintings as documentation has been getting the four corners of a work square with the camera’s viewer frame and lens. Even when aware of the problem, one side of a work would somehow always skew out. Doh! It looks shabby and depresses me. Even when you crop the photo to just the painting, you end up sacrificing an edge or corner in order to square it up, which is also bad, obviously. :cry:

Photographers quickly point out to me that I’m not using a long enough lens and that if I back off from the work further and zoom a long lens in, this will reduce the camera lens’ perspective that tends to diverge/converge parallel sides to a work. In effect a suitably long lens squashes the perspective down to orthogonal projection. I thought a 70 mm lens would be long enough, given that my paintings are only easel size these days, but it isn’t. Damn it. I still couldn’t get the four sides of a work parallel with the camera frame!

Then it occurred to me I could straighten them in Photoshop. This tip probably appears in loads of magazines and online tutes. But I’ve never seen it, never thought to look for it actually. It just came to me one night in bed. Never mind borrowing a brother’s really long zoom lens and fancy Sony to re-photograph the whole bloody batch of paintings again. I could just edit my own, crummy RAW files in Photoshop. Think of the time it would save me! If only I’d thought of this a few years ago when I was digitalising the ancient slide archives… Back then I used a ‘professional’ photographer – and looking at them in Photoshop I quickly realise even they couldn’t always get the painting sides parallel!

So anyway you open the photo file in Ps, duplicate the layer, crop it within a comfortable margin of the sides of the work, use the pen tool to draw a path around the edge of the work – activate as a path on your layers menu. Then >Edit>Transform>Distort. Pick up one of the corner anchor points to the path now with your cursor/Distort tool and straighten a corner or side until parallel with the cropped frame. I just do it by eye, unless unsure. Yeah zoom in and out and that. Then I use the crop tool again (guaranteeing right angles of course) to trace over the edited shape, and if not quite accurate enough > ‘Don’t Crop’ (Ctrl-z) or reverse the crop tool and re-animate a path to the edge of the painting again and fine tune with the Distort option. Save as. 8-)

It sounds freaky doing it this way, but the geometry is sound. I could possibly use the Perspective tool under Transform as well. But that’s the thing about digital files, whether PSD, RAW or JPG – they can effortlessly reshuffle all those little pixels to any perspective or projection. It didn’t take me long to go through eight new paintings and straighten up their edges and tweak the contrast, brightness, etc. They look so much better. I feel so much better. :)
User avatar
CAP
 
Posts: 1081
Joined: Thu Jan 06, 2011 11:38 am
Location: Off-world

Re: A Tip for Straightening Skewed Photos of Paintings

Postby jasperjoffe » Wed Sep 02, 2015 4:42 pm

where's CAP gone?
jasperjoffe
Site Admin
 
Posts: 766
Joined: Mon Jun 07, 2010 2:53 pm

Re: A Tip for Straightening Skewed Photos of Paintings

Postby CAP » Thu Sep 03, 2015 1:11 pm

CAP is in his hammock and a thousand dreams away.... :mrgreen:
User avatar
CAP
 
Posts: 1081
Joined: Thu Jan 06, 2011 11:38 am
Location: Off-world


Return to Life (regular updates on somebody's existence)

Who is online

Users browsing this forum: No registered users and 1 guest