Re: Can we 'twist' a digital picture to be square with the camera?

maryanne kehoe wrote:

What 'trick' am I missing to take a photo of my watercolor paintings?
Can we 'twist' the digital photo to be square with the camera?

I must be doing something wrong. When I edit my digital photographs
of my watercolor paintings, I need to crop the photo but I can NEVER
get the crop edges to be exactly square with the digital camera
photograph of the painting.

Therefore I always find myself losing a few millimeters of painting
so that the photograph is square. What am I doing wrong?

Here is how I take the picture.
a) I put my unmatted 30 inch by 22.5 inch watercolor on a white towel
lying on the ground
b) I stand over the painting, sometimes on a step stool, and position
the Canon PowerShot A95 5MP camera over the center of the painting
c) I snap the shot using flash & macro focus making sure I am as
square as possible and taking an extra inch or so of border all
around to facilitate cropping

Back inside the office, each and every time, when I crop the 2592 by
1944 pixel digital results using Irvanview 3.98 on Windows XP, I end
up with edges that are not square at first. I have to lose some of my
precious painting just to get square edges when I crop.

What am I doing wrong?
What's the trick to get a photo that is head-on with the painting?
Is there a way to twist the painting with software so I don't have to
crop edges and lose painting data?

As far as you described, all you did is correct:
Camera and image aspect ratio are the same, you centered the camera on
the image an made sure it wasn't tilted in any direction.

Maybe the camera images aren't perfectly linear (common lens problems):

Draw a set of squares 10x10, 15x15, 20x20 on a piece of paper and take
some photos as if they were your image. Then measure height and width.
If you find that the squares are no longer square, you can either use
the factor found to rezize your images (not recommended, you lose
quality) or to compare cameras to find one that does a better job.

You will get better results if you are able to use a longer distance
between image and camera as more distortions occur in the wide angle
setting.

Michael

.

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