A-VEKT Image Resampler

A-VEKT 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 exactness
if 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 Raised-Cosine 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 A-VEKT 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　
    ParameterAlpha
    Range0 - 1
    Ideal in theorem (*1)0
    Increasing the valueThe image gets defocused but the bleeding of texts is reduced.
    Reducing the valueThe image gets sharpened but the bleeding of texts is increased.

    ParameterTap Cutoff
    Range1 - 100 (Integer）
    Ideal in theorem (*1)100
    Increasing the valueThe characteristics of the filter get ideal.
    Reducing the valueThe 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 right-bottom 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

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