Pierre Renault in rec.photo.darkroom posted a very interesting method of optically centering a print on a mount.
My humble contribution to photography was to work out an equation to find the print position mathematically.
Wm = Width of mount
Hm = Height of mount
Wp = width of print
Hp = height of print
Distance between top of print and top of mount = (Wm + Wp) (Hm - Hp) / 4Wm
--Russell
"Pierre Renault" wrote in message
news:9010E33FAcheungmomailandnewsc@205.237.233.50 ...
>
> Here's how to automatically optically center any print on any board.
>
> Place the print to be mounted in the upper left-hand corner of the
> board. If you are placing a print under a matte board, then place a
> piece of paper the same size as the desired cut-out.
>
> Bisect the vertical strip to the right of the print and draw a light
> line with a pencil from top to bottom. Do the same thing for the strip
> below the print. Draw a line from where the horizontal line crosses the
> vertical line you've drawn to the right edge of the board.
>
> Next, place a straightedge from the point on the right-hand edge of the
> board where the horizontal line ends to the bottom left-hand corner of
> the print. Mark the spot where the line intersects the line bisects the
> vertical strip.
>
> Place the lower right-hand corner of the print at this intersection.
>
> This works first time, every time.
>
> Pierre
The optically centered print is thus slightly above center.
The following script calculates the print position and graphically illustrates it with a popup window.
Use the same units for each dimension; fractions are optional.
Include the space between the mat and print edges if appropriate; print size and distance from the top will still refer to the print itself.
If you are really picky, reduce the mount dimensions by the part covered by a frame. (You will have to add this to the distance from the top of the mount.)
If the top margin is narrower than the sides after optical centering, consider either making them equal, or if the bottom is then narrower than the top, vertically centering the print. "Correct narrow margins" will do
this automatically.
You may also choose a different centering mode.
1/16
1/8
3/16
1/4
5/16
3/8
7/16
1/2
9/16
5/8
11/16
3/4
13/16
7/8
15/16
.0625
.125
.1875
.25
.3125
.375
.4375
.5
.5625
.625
.6875
.75
.8125
.875
.9375
Note--browsers have minimum window and table sizes, which will interfere with the script if
very narrow mount or print dimensions are used.
"Pierre Renault" wrote in message