Photography Problems

These problems relate to digital imaging in general, whether photographed or scanned.
The examples here are from a copper plate print of Stonehenge scanned at  2321 x 1646 pixels.
Note the 'banding' in the area of clear sky toward the top-right of the picture.
This is the optical interference between the reduced picture resolution and your display monitor resolution.
As the image is enlarged (Fig 2 and Fig 3) the composition lines become more distinct and the interference banding is reduced.
The banding problem is acute on prints with a lot of clear sky or still water, and maps that have a lot of hatched sea around coasts.

Fig 1

Display picture

500 x 355 pixels

The individual lines that
generate the sky's
detail are not visible, but
their presense is interfering with the horizontal lines
generated by the camera at the time of taking.

Fig 2a

Section of sky from
1000 x 709 pixels
Picture lines are now visible, and the problem
has been reduced.
 Fig 2b

Section of sky from
1000 x 709 pixels
As above, but  skewed
by 2 degrees.

Note the vertical bands caused by the interference of the 2 degree lines of the print and the 0 degree lines of your monitor..

With the side-bar move
this image up and down
and observe the columns
of interference marked
by the arrows.

Fig 3

Section of sky from
2321 x 1646 pixels

This shows the lines from
the engraving in greater
Note the spacing of the lines does not hint at the
banding shown in Fig 1.

A Past Pages Information page              Tony Nicholls  2008