Search found 188 matches

by henrywho
2012-09-23T08:03:37-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 396255

Re: best downsampling method for DSLR photographs

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.......
by henrywho
2012-09-23T08:00:31-07:00
Forum: Users
Topic: line drawings to test downsizing methods
Replies: 10
Views: 12463

Re: line drawings to test downsizing methods

I prefer linear light with EWA lanczos3Sharpest
by henrywho
2012-09-20T19:33:17-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 396255

Re: best downsampling method for DSLR photographs

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.
by henrywho
2012-09-19T22:34:22-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 396255

Re: best downsampling method for DSLR photographs

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 looking "brighter" (in contrast...
by henrywho
2012-09-19T03:54:54-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 396255

Re: best downsampling method for DSLR photographs

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=0.8882642150...
by henrywho
2012-09-17T17:09:57-07:00
Forum: Users
Topic: sigmoidized EWA LanczosRadius3 ... and tensor Quadratic
Replies: 56
Views: 53344

Re: sigmoidized EWA (-distort resize) LanczosRadius3

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 "border" followed by a ...
by henrywho
2012-09-16T00:58:26-07:00
Forum: Users
Topic: sigmoidized EWA LanczosRadius3 ... and tensor Quadratic
Replies: 56
Views: 53344

Re: sigmoidized EWA (-distort resize) LanczosRadius3

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.
by henrywho
2012-09-15T09:27:44-07:00
Forum: Users
Topic: sigmoidized EWA LanczosRadius3 ... and tensor Quadratic
Replies: 56
Views: 53344

Re: sigmoidized EWA (-distort resize) LanczosRadius3

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...
by henrywho
2012-08-27T20:15:39-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 438138

Re: proper scaling of the Jinc filter for EWA use

: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:filter=Jinc -define filter:window=Jinc -define filter:lobes=4 -d...
by henrywho
2012-08-23T05:14:13-07:00
Forum: Bugs
Topic: Luv colorspace showing errors
Replies: 4
Views: 5607

Re: Luv colorspace showing errors

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

viewtopic.php?f=3&t=21664
by henrywho
2012-08-19T08:48:22-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 438138

Re: proper scaling of the Jinc filter for EWA use

NicolasRobidoux wrote:It is exactly the built-in value currently used for LanczosSharp.
Probably the same case for Lanczos2Sharp :lol:
by henrywho
2012-08-16T02:09:20-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16843

Re: Resizing pictures with sharp B/W lines under LUV

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...
by henrywho
2012-08-15T21:00:25-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16843

Re: Resizing pictures with sharp B/W lines under LUV

fmw42 wrote: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 that your LUV images do not have any color cast.
by henrywho
2012-08-15T18:11:13-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16843

Re: Resizing pictures with sharp B/W lines under LUV

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.
by henrywho
2012-08-15T17:10:32-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16843

Re: Resizing pictures with sharp B/W lines under 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.