Re: Slide scanners

[P3D John Ohrt <johrt@xxxxxxx>]

P3D H a r o l d B a i z e wrote:

> I bought it because I found that I'm spending one to two
> hundred dollars a year to scan slides at a service bureau.
> Even with the high cost the scans often contain some minor
> rotation, which is very difficult to correct later.

Sadly, that is case.

The scan is possibly skewed as well.  Whether or not the scan is skewed as
well as rotated, using a skew correction to correct for minor amounts of
rotation is mathematically valid!!!

If you are really fussy, enlarge the image using interpolation, and then
skew correct at high precision.  Trim the skewed image to correct
proportions and then reduce the image to original scale.

It is nice to use floating point math, but this is one type of operation
where the errors from integer math of low cost image processing is rarely
noticeable.

Regards,

--

John Ohrt * Toronto * ON * Canada





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