resize images

[tondamen]

Aloa,

I work in the field of digitization of our cultural heritage. We use Hasselblad as camera, a bookcradle developed in the house and broncolor as lighting. Besides Phocus we use Photoshop software. Problem of photoshop is that the images in high contrast areas are clipping when using the opportunity to reduce images, for example 2500 to 2500 pixels (fit in). My feeling is that Photoshop(excuses for the dutch photoshop version), is not calculating properly.


some example files can be found via onedrive:

https://onedrive.live.com/redir?resid=1 ... lder%2ctif

Naturally very curious about the imagemagick possibilities !!!

Regards,

Ton

T.Damen@rijksmuseum.nl

prive:
​​Ton Damen
Columbusstraat 5
4812 RR Breda
Netherlands
+31 6​ ​40​ ​20​ ​84​ ​77
tondamen1@gmail.com
​skype: tondamen1​

[snibgo]

There have been many threads on this forum from users with similar projects, photographing book pages to digitise them, probably with smaller budgets than the Rijks Museum.

I don't use Photoshop, but I doubt that it has more problems with clipping than any other software.

Resizing can be done simply by removing pixels. This introduces no new colour values, but the results are horrible. Most resizing methods look far better, but introduce new colours. This means the output will contain pixels with colours that are not in the input.

Your file "M-RP-P-1929-173-00-Voorbeeld clippen.tif" is 16 bits/channel/pixel and contains pixel values extending from 0 to 65535. I suppose the photograph did not contain those extremes, but it has been through some processing.

So some values are already at 0 or 65535, and resizing will push more pixels to those extremes. They will be "clipped".

Resizing is best done before stretching values to 0-65535.