Search found 188 matches

by henrywho
2012-08-15T09:42:27-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16678

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

Not sure if it is something like rounding errors:

Image
by henrywho
2012-08-15T05:07:05-07:00
Forum: Bugs
Topic: Resizing pictures with sharp B/W lines under LUV
Replies: 13
Views: 16678

Resizing pictures with sharp B/W lines under LUV

Win32 ImageMagick 6.7.8-10 2012-08-10 Q16 DLL convert rings_lg_orig.png -colorspace LUV -resize 25% -alpha off +repage -colorspace sRGB -quality 95% rings_sm_luv1.png convert rings_lg_orig.png -set colorspace sRGB -colorspace LUV -resize 25% -alpha off +repage -colorspace sRGB -quality 95% rings_sm_...
by henrywho
2012-08-13T10:03:10-07:00
Forum: Digital Image Processing
Topic: "Sigmoidal" minimization of resampling filter haloing & blur
Replies: 136
Views: 268927

Re: "Sigmoidal" minimization of resampling filter haloing &

NicolasRobidoux wrote:I am convinced that linear light is "it" when downsampling. But I am not certain.
Me neither, especially after Anthony's comment that while linear RGB's intensity is linear, its colors are not.
by henrywho
2012-08-12T23:02:23-07:00
Forum: Digital Image Processing
Topic: "Sigmoidal" minimization of resampling filter haloing & blur
Replies: 136
Views: 268927

Re: "Sigmoidal" minimization of resampling filter haloing &

I wonder how much these contrived tests really tell us. Sorry being off-topic. Actually I should have posted in another thread where Anthony talks about LAB and LUV. Even if they are too harsh sometimes, these contrived tests do help revealing abnormality. For example, the LUV-downsize above produc...
by henrywho
2012-08-12T17:30:57-07:00
Forum: Digital Image Processing
Topic: "Sigmoidal" minimization of resampling filter haloing & blur
Replies: 136
Views: 268927

Re: "Sigmoidal" minimization of resampling filter haloing

Henry: "Brasseur test" conclusion: stick to linear light when downsampling. Seems LUV works very well in Brasseur-Dalai test: convert gamma_dalai_lama_gray_tft.jpg -distort resize 50% -quality 95% -sampling-factor 1:1:1 dal_tft.jpg convert gamma_dalai_lama_gray_tft.jpg -set colorspace sRGB -colorsp...
by henrywho
2012-08-12T08:03:05-07:00
Forum: Digital Image Processing
Topic: [SOLVED] making sense of sigmoidal-contrast
Replies: 38
Views: 74588

Re: making sense of sigmoidal-contrast

NicolasRobidoux wrote:When I have a minute, I will change enhance.c so that sigmoidal-contrast not use a LUT in HDRI mode
Hope we will have an official HDRI compile. :D
by henrywho
2012-08-12T07:56:35-07:00
Forum: Users
Topic: PNG resize question
Replies: 6
Views: 8726

Re: PNG resize question

It works again by adding "-set colorspace sRGB".

Code: Select all

convert rings_lg_orig.png -alpha off -set colorspace sRGB -colorspace RGB -filter RobidouxSharp -distort resize 50% -colorspace sRGB -alpha off +repage -quality 95% test1b.png
by henrywho
2012-08-11T06:54:29-07:00
Forum: Users
Topic: PNG resize question
Replies: 6
Views: 8726

Re: PNG resize question

With 6.7.8-9 Win64 DLL, gray images appear to be causing troubles again: convert rings_lg_orig.png -alpha off -colorspace RGB -filter RobidouxSharp -distort resize 50% -colorspace sRGB -alpha off +repage -quality 95% test1.png convert rings_lg_orig.png -alpha off -evaluate POW 2.2 -filter RobidouxSh...
by henrywho
2012-08-10T09:49:03-07:00
Forum: Users
Topic: Summary: reducing (downsizing) natural images
Replies: 4
Views: 7743

Re: Summary: reducing (downsizing) natural images

A small note that some ppls like to take BW (gray) photos but IM6 behaves weirdly with gray photos and -colorspace options. Better use -gamma with gray photos for the time being.
by henrywho
2012-08-10T09:39:22-07:00
Forum: Users
Topic: Summary: reducing (downsizing) natural images
Replies: 4
Views: 7743

Re: Summary: reducing (downsizing) natural images

Are "LanczosRadiusN" and "LanczosSharpestN" available directly in IM6 or 7 now?
by henrywho
2012-08-09T18:05:48-07:00
Forum: Users
Topic: PNG resize question
Replies: 6
Views: 8726

Re: PNG resize question

r u really upsizing by 1000 times?
by henrywho
2012-08-08T03:58:05-07:00
Forum: Digital Image Processing
Topic: "Sigmoidal" minimization of resampling filter haloing & blur
Replies: 136
Views: 268927

Re: "Sigmoidal" minimization of resampling filter haloing

Henry: I'll have to redo the downsampling tests with the newly fixed sigmoidal-contrast code. (IM7 is closest to fixed, and the fix is not complete for orthogonal resize methods with negative lobes.) Other things to do for a while. Remember to include this test case: http://www.4p8.com/eric.brasseu...
by henrywho
2012-08-07T01:00:10-07:00
Forum: Users
Topic: PDF to JPG – Trying to obtain a “Crisp” (not fuzzy) JPG
Replies: 6
Views: 15663

Re: PDF to JPG – Trying to obtain a “Crisp” (not fuzzy) JPG

To add even more acutance (sth like edge sharpness), convert -density 288 image.pdf -filter lagrange -distort resize 25% -quality 95 -sampling-factor 1:1 image.jpg Linear RGB resize is mathematically more correct but this is probably counter-productive in this use case: convert -density 288 image.pd...
by henrywho
2012-07-26T18:46:16-07:00
Forum: Digital Image Processing
Topic: future of image enlargement?
Replies: 61
Views: 128261

Re: future of image enlargement?

Hey, it's not fair. I am an amateur using defaults and you are THE expert using tuned parameters. :lol:
by henrywho
2012-07-26T09:50:14-07:00
Forum: Digital Image Processing
Topic: future of image enlargement?
Replies: 61
Views: 128261

Re: future of image enlargement?

NicolasRobidoux wrote:
henrywho wrote:...
Let me try Avisynth+NNEDI3+EEDI3 tonight.
Thank you Henry.
Pure NNEDI3
Image