MAKE A MEME
View Large Image
| View Original: | Kcc_rescale_03b_Gimp_lanczos_interpolation.jpg (557x425) | |||
| Download: | Original | Medium | Small | Thumb |
| Courtesy of: | commons.wikimedia.org | More Like This | ||
| Keywords: Kcc rescale 03b Gimp lanczos interpolation.jpg spatial aliasing that can result when an image that contains some strong spatial frequencies is digitally rescaled An image of an 1801 engraving of King's College Chapel Cambridge was used as a test object and resized to 50 using different filters and different programs <p> The image on this page was resized to 50 using GIMP 2 6 12 with the lanczos interpolation option -- i e implicitly applying a Lanczos filter to the image The result produced seems essentially identical to that obtained in the Image Magick box filtered image Compared to simple decimation the unwanted MoirĂ© pattern s are much reduced and are essentially no longer visible in the road and the building and the clouds However although softened a bit they do still remain in the sky <p> Identical results to a box filter are not on the face of it what one would expect; and furthermore they are rather different to the Image Magick Lanczos result so it could be that what GIMP 2 6 12 is actually implementing here may be different to what it is advertising <p> Other images in the series look at the results of using various available lowpass filter s to try to further minimse or suppress such artefacts 1801 F Roffe after P Nash 1801 - King's College Chapel - sanders13001 jpg an engraving first published in 1801 John Roffe 1769-1850 engraver after Frederick Nash 1782 “1856 File Kcc rescale 01 gimp no interpolation jpg -- GIMP by decimation File Kcc 01 im point jpg -- ImageMagick by decimation File Kcc rescale 02 im box filter jpg -- ImageMagick using a box filter File Kcc rescale 03a Gimp bicubic interpolation jpg -- GIMP using a bicubic filter allegedly File Kcc rescale 03b Gimp lanczos interpolation jpg -- GIMP using a Lanczos filter allegedly File Kcc rescale 04 im triangle jpg -- ImageMagick using a ramp filter File Kcc rescale 05 im Lanczos jpg -- ImageMagick using a Lanczos filter File Kcc rescale 06 im default jpg -- ImageMagick default a Mitchell filter PD-old-100 Uploaded with UploadWizard Aliasing | ||||
