On 2/15/2010 10:05 AM, J. Clarke wrote:
Brent wrote:
On Mon, 15 Feb 2010 06:12:34 +0000 (UTC), Brent wrote:

Actually I ended up taking a photograph of the document
Then printing that photograph to PDF
But the results are substandard

I should mention that the reason the results sucked were mostly that
some strange effect cropped in the picture so that NONE of the four
sides were parallel with each other!

I'm not sure why, but, somehow the camera introduced a bending of the
edges!

Google "barrel distortion" and "pincushion distortion".

Somehow, the 8.5x11 sheet of paper, when photographed, had the sides
bent at a slight angle such that cropping could only be done by
cutting into the margins.

Even then, the edges of the text didn't coincide evenly with the
edges of the cropped edge of the paper.

Three options.

First, if your lens can fill the frame with the document through its entire
zoom range, try different focal lengths and see if it has a low-distortion
sweet spot--if it does then remember to use that for document copying.

If it doesn't have a sweet spot that's good enough, then you need to do
distortion correction.

To do distortion correction, first check whatever image editor you are using
and see if it has a built in capability--if so try that. If it's not good
enough then you need a third-party product. PTLens works and is cheap, DxO
has more features and is not so cheap. Both have free trials.

Or you can if you are using a DSLR or Micro 4/3 camera get a purpose made
macro lens.


If your camera has a moderate number of pixel, instead of making the
document as large a percent of the image as possible, back down and make
the document a much smaller percent of the total image. This should help
with the edge distortion as there is no distortion in the middle area of
most lens.

To get the final image, crop the image to document size. Most text
documents do not require a significant number of pixels in the image to
get a readable image. I have seen 640X480 document images that are
quite readable. Most modern cameras, even with significant cropping
will give you more pixel in the image than 640X480