TESTIMAGES

This project contains archives of images and scripts for scientific testing purposes.
The main mission of this project is to give a common testing framework for image interpolation methods (image enlargement), so the various methods can be easily compared.
This project includes Octave/Matlab scripts to calculate metrics about the differences between the original and interpolated images of the TESTIMAGES archive.
Reference metrics for standard interpolation methods are already calculated and available.

Project

• Download TESTIMAGES archive
• Project detail and discuss

Content of the testimages.zip archive

Images are divided in 3 main folders:

• ART: Artificial 8bit grayscale images.
• GRAY: Natural 8bit grayscale images.
• RGB: natural 3x8bit (Red, Green, Blue) color images.

Each main folder contains:

• 1 subfolder with 100 original images (..._OR_1200x1200). The size of these images is 1200 x 1200 pixels.
• 8 subfolders containing reduced versions of the original images. Reduction factors are: 2, 3, 4, 5, 6, 8, 10 and 12. The folder name indicate the reduction factor and the size of the images.

Reduction algorithm

The size of images has been reduced by averaging the values of RxR sub-arrays (where R is the reducing factor).

For example, if the reduction factor is 3:

	X=(A+B+C+D+E+F+G+H+I)/9
	
	+---+---+---+
	| A | B | C |
	+---+---+---+       +---+
	| D | E | F |  ==>  | X |
	+---+---+---+       +---+
	| G | H | I |
	+---+---+---+

Content of the testimages_zoom_*.zip archives

These archives contains enlarged images of the testimages.zip archive.
The images are enlarged with various interpolation methods.
The size of all images is 1200 x 1200 pixels, to be compared with the original images on the testimages.zip archive.

• testimages_zoom_nn.zip : Images enlarged with NEAREST-NEIGHBOR interpolation method (Octave imresize 'nearest').
• testimages_zoom_bl.zip : Images enlarged with BILINEAR interpolation method (Octave imresize 'bilinear').
• testimages_zoom_bc.zip : Images enlarged with BICUBIC interpolation method (Octave imresize 'bicubic').
• testimages_zoom_l2.zip : Images enlarged with LANCZOS2 interpolation method. The following ImageMagick command has been used: convert INPUT_IMAGE.png -resize 1200x1200 -filter Lanczos -define filter:lobes=2 -format png -compress LZW -quality 1 OUTPUT_IMAGE.png
• testimages_zoom_l3.zip : Images enlarged with LANCZOS3 interpolation method. The following ImageMagick command has been used: convert INPUT_IMAGE.png -resize 1200x1200 -filter Lanczos -define filter:lobes=3 -format png -compress LZW -quality 1 OUTPUT_IMAGE.png
• testimages_zoom_mn.zip : Images enlarged with CUBIC MITCHELL interpolation method. The following ImageMagick command has been used: convert INPUT_IMAGE.png -resize 1200x1200 -filter Mitchell -format png -compress LZW -quality 1 OUTPUT_IMAGE.png

Content of the testimages_metrics.zip archive

This archive contains Octave/Matlab scripts to calculate metrics about the differences between the original and interpolated images of the TESTIMAGES archive.
This project includes reference metrics (DATA directory) calculated for standard interpolation methods on the other archives.

Content of the testimages_hdtv.zip archive

This archive contains images for testing colors and geometry of High-Definition Televisions (HDTV) with 1920x1080 pixels.

License

• Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)
• Human-readable summary: http://creativecommons.org/licenses/by-nc-sa/3.0/
• Legal code (the full license): http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode