Benchmarks: the PCIF image set
Beyond two classical image sets used for benchmarks for image processing algorithms, the waterloo image set and the kodak image set, the PCIF algorithm has been tested on another set of images gathered by the author. The goal of proposing a new benchmarking set was to offer a wider set of varying characteristics, as the kodak image set contained only photographical images of the same dimension (and probably similar source) and the waterloo image set contains only a few images of which some with very peculiar traits weight heavily on the global results.
To better simulate characteristics of all the possible images that could be compressed, images in this set have been chosen to have different characteristics between the following:
- Source (photographic, scanner, computer-generated, photographic/cg hybrid)
- Image quality
- Quantity of sharp edges
- Variety of colors
As it could be expected by the variety of images, also the results are very different from an image to another. PNG files result to be averadgely from 25% to 40% bigger than pcif files. Very regular images (sphere, vangoh - autoritratto) are an exception as the PNG algorithm seems to obtaine very well-compressed files.
Regarding the comparison with jp2 files, the pcif algorithm obtains usually slightly worse results for photographical images (as fishes, piccione, pine tree arch, chess_clip...) but is significatevely better for computer generated and for photo-retouched images (bluesphere, dice, labyrinth, brewing_storm...). The global size of pcif files is 5% smaller than the one of jp2, that is an a good intermediate result between the ones for the kodak and waterloo image sets. The introduction of this new image set has determined also two images that give the highest difference in compression efficiency between the two formats: image fishes (jp2 is 9% smaller that pcif) and labyrinth (jp2 is 4 times bigger than the pcif file, this is quite an 'extreme' example though).
For what regards this image set, the JPEG-LS files produce very good results for photographical images, and the worst performances for the computer generated images are not so bad; for these reasons, this format results to be globally the best for these images.
In the table, the BMP column represents the size of the uncompressed image. The settings used for the creation of the files are described here.
In conclusion, tests on this image sets are coherent with the ones done on 'classical' benchmarking sets, and give us some additional information. Anyway, benchmarks should always be read with care, as results may be different from image to image depending on a great number of factors. Other benchmarks used to test the PCIF format have been done on the waterloo true color image set and the kodak image set, two popular benchmarking sets, and on a fourth image set of large images proposed on www.imagecompression.info. Finally, if you are interested in the PCIF algorithm, you are encouraged to test its performances yourself by downloading the program in the download section.
Update: the BCIF algorithm, evolution of the PCIF algorithm, has also been included in the benchamrks. It has a better compression ratio and a strongly inscreased speed. Take a look at the BCIF homepage.
|Filename \ size (KB)||BMP||BCIF||PCIF||JPEG-LS||JPEG2000||PNG|
|dali - die bestandigkeit de||467||93||94||162||210||107|
|earth from space||5625||719||844||763||858||1130|
|from overlook 3||1215||603||637||573||623||851|
|pine tree arch||1215||466||491||437||468||652|
|vangogh - autoritratto||1553||446||473||483||524||443|
Since the images have been mainly found on the net, some of them may be subject to copyright and could not be displayed directly on this site. If you are interested in finding these images, you can contact the author.