Search found 188 matches

by henrywho
2012-07-06T22:27:04-07:00
Forum: Digital Image Processing
Topic: Image resizing with LCD sub-pixel awareness (aka ClearType)
Replies: 18
Views: 66259

Re: Image resizing with LCD sub-pixel awareness (aka ClearTy

I wanna try testing with this concept. Using the sample image at http://forums.dpreview.com/forums/read.asp?forum=1006&message=40282142 the anti-aliasing effect seems not easily noticeable. convert.exe 7640_CO40_FM1-175pct_sRGB.jpg -colorspace RGB -filter RobidouxSharp -distort resize 1800x900! -cha...
by henrywho
2012-06-04T03:58:06-07:00
Forum: Digital Image Processing
Topic: [SOLVED] Donate a high quality raw image to science?
Replies: 67
Views: 130554

Re: [SOLVED] Donate a high quality raw image to science?

"-q 1" is VNG ... um....

http://www.libraw.org/articles/bayer-moire.html

Perhaps rawtherapee with LMMSE or AMaZE using "neutral" BW? It seems to have linux binary distributions.
by henrywho
2012-06-03T01:21:16-07:00
Forum: Digital Image Processing
Topic: [SOLVED] Donate a high quality raw image to science?
Replies: 67
Views: 130554

Re: [SOLVED] Donate a high quality raw image to science?

Actually, the color of "apartment.tif" is a bit off, kinda green-cast there. What something like: LibRaw-0.14.6\bin\dcraw_emu.exe -w +M -H 2 -fbdd 1 -dcbe -q 10 -o 1 -g 1 1 -6 apartment.rw2 ImageMagick\convert.exe apartment.rw2.ppm -set colorspace sRGB -crop 2520x2520+530+1249 +repage -define filter...
by henrywho
2012-05-29T18:22:19-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

That "whitepaper" is for marketing guys, nothing technical

I tend to believe that they are re-using the quick resample routine (the one for realtime display and "pureview" digital zoom) for that "oversampling" task, giving the sub-par results.
by henrywho
2012-05-29T05:36:19-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

[duplicate post deleted]
by henrywho
2012-05-29T05:08:51-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

Conjecture With my favorite methods, no negative total weight can occur. as long as that there is no programming or compiler bugs (or different rounding conventions, etc.) 8) btw, though not DSLR, Nokia is introducing a 41MP mobile phone with a 1/1.2" sensor. :shock: Information and samples at: htt...
by henrywho
2012-05-20T21:39:56-07:00
Forum: Users
Topic: raw to JPEG conversion
Replies: 3
Views: 9489

Re: raw to JPEG conversion

ImageMagick seems to be converting raw files with the bundled dcraw 9.06 which is a bit too old.

You may want to take a look at the dcraw "clone" in LibRaw (http://www.libraw.org/download) which has more demosaic and denoise methods.
by henrywho
2012-05-20T17:18:26-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

But if what you say is true, why not use an even more extreme gamma change on both ends rather than just the .45455 and inverse built into sRGB? Does that make any sense? I just find linear light downsize produces images that match better (brightness wise) to viewing the original 1:1 image a few fe...
by henrywho
2012-05-20T07:59:57-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

In my testes, images with heavy PP(post processing) have a tendency to be worst when using linear light due to the fact that the PP may already have enhanced the details... I tend to take a simpler explanation. Artifacts are unwanted patterns formed by interpolated values generated by resizers. The...
by henrywho
2012-05-20T04:56:59-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

Pictus wrote:convert BackPack.png -filter Lanczos -define filter:lobes=4 -define filter:blur=0.88451002338585141 -resize 1200x1200 Lanczos_4.png
....
Aren't these blur values designed for distort resize?
by henrywho
2012-05-19T09:50:00-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

NicolasRobidoux wrote:Do you see problems with the downsample of the apartments image I put in the test image bank? If you do (please explain), I may redo it.
No, it's the image itself, containing high contrast sharp lines. I tried sizing it down by 50% and then up by 2X, the lines become awful.
by henrywho
2012-05-19T09:41:14-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

Pictus wrote:use some contrast detect algorithm to choose the good one... :)
I think the range from EWA-Robidoux to EWA-Catrom should cover most uses.
by henrywho
2012-05-18T22:31:23-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

P.S. I just checked: Indeed box filtering by 3 of a crop to multiples of 3 in both directions shows moire. I'm really happy now that none of the images in the test image bank I prepared is moire prone. But apartment.tif is alias-prone. 8) P.S. 2 Henry, I am truly very thankful for all your feedback...
by henrywho
2012-05-16T17:29:34-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 389519

Re: best downsampling method for DSLR photographs

I remember that cubic calculation are quite a bit faster than, e.g. Jinc, for EWA, right? The time needed for such search should be acceptable. Indeed, the sharper the source, the less sharp the downsizer should be. If we have some algorithm to evaluate the sharpness, can we have some automatic calc...