Apple

On Aug 1, 2010, at 8:24 AM, Luther Fuller wrote:

On Jul 31, 2010, at 9:36 PM, Robert Poland wrote:

I've got a challenge for the math-a-magicians out there.

Using the script below on a picture 3264x2448 i get a result in the display Dialog for 499 pixels.

THE CHALLENGE:
Is there a simple fix to get a result of 500 pixels?

No! Or, to put it another way, "Does 3264 contain 5 as a factor?"

If you factor 3264 completely, you get ...

3264 = 2^6 * 3^1 * 17

Scaling this to exactly one fifth its original size is impossible, since 5 is not a factor of 3264.
Your image software has to round 3264/500 = 6.528 ≈ 6.53 and 3264/6.53 = 499.84...
(And your image software does it differently than my example.)

If you want to scale EXACTLY, you have to ...
Scale-up by an integer value.
Scale-down by a (integer) factor of both dimensions.

Another example:
If your image measures 2749 x 5399 pixels,
you can never scale it down by any integer value, 1/n.
Why? Because both these numbers are primes!

The example sent by email@hidden does scale a 2749 x 5399 picture to 500 x 981.

set theFile to chooseFile

tell application "GraphicConverter"

activate

open theFile

set {picWidth, picHeight} to image dimension of window 1

set scale500 to (500 / picWidth)

scale window 1 horizontal scale500 vertical scale500

repeat

set {picWidth, picHeight} to image dimension of window 1

if picWidth < 500 then

scale window 1 horizontal 1.0025 vertical 1.0025

else

exit repeat

end if

end repeat

tell application "System Events"

activate

display dialog "Width=" & picWidth

end tell

close window 1 saving no

end tell

Robert Poland - Fort Collins, CO

References:
	>Re: Math-a-magic puzzle (From: Luther Fuller <email@hidden>)