Legacy ImageMagick Discussions Archive

NicolasRobidoux wrote:it's about as sharp as EWA Mitchell, but it has almost no second halo, and it definitely suppresses moire better.
viewtopic.php?f=1&t=20992&start=225#p90392

But EWA Mitchell is not sharp enough.......

I prefer linear light with EWA lanczos3Sharpest

The moire pattern of the Fly is my second concern.

My first concern is the change in overall brightness (i.e., de-focus my eyes and watch the compound eyes). Yet, unless we have a well-tuned monitor, it is impossible to detect judge whether there is any real brightness change.

From the zipper on the left, I think Ginseng3 and EWA-LanczosSharp have similar "sharpness", but then from the backpack surface, EWA-LanczosSharp have less "noise". For "Fly", I found something strange. On down-sampling to 403x600, Ginseng3 is making the compound eyes l...

Yup, there are fewer halos; unfortunately, it also reduces the reflection of the nylon fibre vastly. May we use a 2-lobe downsizer with lower sigmoidization value? The backpack photo is a special use-case. EWA Catrom, "Cub-grange" (cubic @ c=0.4846), Lagrange and Lanczos2VerySharp (blur=0....

Did you resample through linear light or straight sRGB? I did it in linear light. Actually, it is an incorrect description. When downsizing, EWA Lagrange generates "only" a dark "border" around a sharp edge (as in 2-lobe Lanczos and Cubic) but 3-lobe Lanczos generates a dark &qu...

NicolasRobidoux wrote:Interesting. Thank you Henry.

And some time ago I have tested downsizing of black and white texts with EWA lanczos3, catrom and lagrange. I remember that EWA lagrange produces dark halos more than white halos. Perhaps it's the reason I like it better.

You might mention Lagrange as about on par or perhaps some better (according to henrywho) as catrom. For web-size downsampling of natural photos, EWA Lagrange appears similar to EWA Cubic @c=0.483 ~ 0.485 But for artificial ones like rings_lg_orig.png, EWA Lagrange behaves quite a bit differently t...

:shock: Have I missed anything? :shock: if /i "%FILTER%" == "JincJinc2Old" set RESZFT=-filter Lanczos2Sharp if /i "%FILTER%" == "JincJinc3Old" set RESZFT=-filter LanczosSharp if /i "%FILTER%" == "JincJinc4Old" set RESZFT=-define filter:filt...

Seems pure LUV roundtrip is okay .... but not if resizing is done under LUV

viewtopic.php?f=3&t=21664

NicolasRobidoux wrote:It is exactly the built-in value currently used for LanczosSharp.

Probably the same case for Lanczos2Sharp

The brightness should be incorrect because of the incorrect gamma assumption. Still the image should remain gray only. One bug in Q16 compiles is that the image is no longer gray. Another bug in Q16 compiles is having abnormal dots generated. The following sample has a light gray dot at the 6-o-cloc...

The rings image is grayscale under IM 6.7.8.3 and higher and not sRGB. I thought the image is "sGray" and so I use "-set colorspace sRGB" (not "-colorspace sRGB") before "-colorspace LUV" and "-colorspace LAB". Is it causing the troubles? It seems t...

fmw42 wrote:Have you tried under HDRI compile to see if it behaves differently there?

no, coz the HDRI build (ImageMagick 6.7.6-1) is old and it does not support LUV.

magick wrote:This suggests that the conversion to and from LUV is correct.

It seems the resize (and distort resize too) codes are not behaving properly under LUV.