trouble understanding -resample

[g_blur]

Abstract:
* I believe it's caused by the same effect as described here here. (German, but you can simple have a look at the images)
* Suggestion is to scan the postcard in a very high resolution (600dpi or even 1200). Apply rescaling and bluring (Gauss?).

What I tried:

Code: Select all

convert in.tif -resample 300x300 -blur 0x2 -format png out.png

* I want to include the images into a latex document (pdflatex). It is important that the images appear in the same dimensions as the original postcards.
* the blur filter seems to do a good job (not sure yet)
* pdflatex automatically reads the dimensions of the image.

Problem:
* If I don't use -resample, the images appear in the correct dimension, but use too much file space
* If I use -resample the image appears much larger.
* I also read that the print result should be better when using 300dpi files

Questions:
* Why do the images not appear in the correct dimension?
* Any other suggestions how to do this?
* Scan with 300dpi directly (This may result in a worse outcome of the blur filter?)?
* I don't use any filters of the Epson scan software. Should I?

altogether
* How to use the scanner device, ImageMagick and pdflatex to get the best result for printing scanned postcards at a professional printer shop?

Thanks for all hints and suggestions.

[anthony]

The page you refer to seems to be more about removing the printing pattern of a scanned image, and not about resizing. Though resizing can help with the problem.

One better method of removing that pattern is to maybe use 'notch filter', or 'descreen' filter with a fast fourier transform.

This is still quite new in ImageMagick, and examples and techniques are still being worked out.Similarly for the extra operators for handlign FFT images. However notch filtering is quite well defined.

See The pages I only made visible to the public yesterday!
http://www.imagemagick.org/Usage/fourier/

I'll leave it to Fred Wienhaus to explain more.