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Scaling Up or Down?

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Article Index
Scaling Up or Down?
Evaluation with Imatest
Conclusions
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There have been some discussions on Luminous Landscape forums regarding scaling of images. I have made some small experiments on the issue, and here is what I have found.

 

The discussion on LuLa is here.

 

Bart van der Wolf has a pair of very good articles on the issue:

 

Methods

  • Two cameras were tested
  • Sony Alpha 55 an APS C camera with 16 MP and relatively weak OLP-filtering
  • Sony Alpha 900 a full frame camera with 24 MP and a heavier OLP-filter
  • Both cameras were used with their normal zooms, in both cases "Zeiss labeled" Sony lenses.
  • Tripod position was unchanged an field of view was matched approximately using zoom.

Subject

The subject was a table top setup using white and black coffecups, a couple Color Checkers, a flower, a Dollar bill and a "fake" USAF test target with bars added for Imatest evaluation.
All scaling was done using bicubic, with no options.

Sample images and analysis

First, the Alpha 900 at original size and Alpha SLT 55 upsized using "bicubic". Note that the SLT significant color moiré on the Dollar bill. Click on the images for full size.

 

The next two images show SLT 55 image in original but Alpha 900 dowsized to same size. Click on images for actual pixels!



Last Updated on Saturday, 28 April 2012 23:00  

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