AVEKT Image Resampler
AVEKT Image Resample is a software to resize an image accurately based on
Nyquis–Shannon sampling theorem.
An image can be enlarged or shrunk clearly.
Principle
According to the sampling theorem, the original signal can be reconstructed with exactnessif the signal is sampled at a sampling rate which is twice or more of the maximum frequency contained in the signal.
However, a simple algorithm such as moving average is employed in most of image processing software,
and the original information cannot be reconstructed clearly.
Furthermore, the condition of the sampling theorem is not fully met in actual due to
high frequency components included in an edged object such as texts.
Thus, we employ a RaisedCosine Filter with adjustable relaxation based on Sinc filter
which comes from the sampling theorem to reconstruct the original signal.
Examples

Original image

Left : Enlarged to 110% by AVEKT Image Resampler. (Alpha=0.5, Tap Cutoff=100.)
Right : Enlarged to 110% by Paint in Microsoft Windows.

Left : Reduced bleeding by adding tap cut off to Right.（Alpha=0, Tap Cutoff=2.)
Right : Enlarged to 110% using pure Sinc filter.（Alpha=0, Tap Cutoff=100.)
This is ideal in the sampling theorem but aliasing (bleeding) is generated due to the high frequency components in texts which is exceeding the assumption.
Usage

Open an image file, select Edit>Resample, enter the parameters as below, and press OK.
Note that it takes long processing time when the size of the image is large.

Adjustment of Parameters
Parameter Alpha Range 0  1 Ideal in theorem (*1) 0 Increasing the value The image gets defocused but the bleeding of texts is reduced. Reducing the value The image gets sharpened but the bleeding of texts is increased.
Parameter Tap Cutoff Range 1  100 (Integer） Ideal in theorem (*1) 100 Increasing the value The characteristics of the filter get ideal. Reducing the value The bleeding of texts is reduced but the distortion is increased.
(*1) : Assume the condition of the sampling theorem is fully met.

Zoom for display
The viewing image can be resized by the slider at the rightbottom of the top window.
The data will be truncated if the image is shrunk, and the data will be repeated if the image is enlarged.
Note that the resampling is not performed because is just for the convenience to check details or overview.
Please check the correct image with 100% size.
Operating System Requirement
 Windows Vista, 7, 8.1 or 10. (32 or 64 bit version)
License Key

The program can be launched 30 times for trial use when License Key is not set.
After expiring the trial, the resizing of the image by Edit>Resample will not function.
However, the program can be used as an image viewer.
After you purchase a License Key, select File>License, then enter Email Address and License Key.
A corresponding Email Address for the License Key must be used.
The license authentication is performed offline, and internet connection is not required.

A license key can be purchased at the following site.
https://www.avekt.com/store/Products/SoftwareLicenses
Download

Image Resampler Ver1.4
The installer and program are signed with EV Code Signing certificates.