Search found 109 matches

by rnbc
2011-08-07T16:24:32-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Re: Does Image Magick have Tonemapping operators?

fmw42, the thing is: you should try your approaches with a real high dynamic range image. Try this ones , sorry about the low speed but that's my PC in a relatively low speed connection. The image I've shown was obtained from the data in cascata_praia_da_ursa.exr, and sala_com_janela.exr is a real c...
by rnbc
2011-08-06T17:42:23-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Re: Does Image Magick have Tonemapping operators?

As not all of us have this software, perhaps you would not mind posting your end result. See above, I've included the final result in the post ;) Also in the same flickr set you have more examples of images made with that pipeline, with pfstmo_mantiuk06 and other tonemapping operators. Anyway, the ...
by rnbc
2011-08-06T16:36:16-07:00
Forum: Digital Image Processing
Topic: JPEG noise, a comparison study
Replies: 5
Views: 19154

Re: JPEG noise, a comparison study

There is nothing in the JPEG standard specifying you should use sRGB. At least in the version I have. They seem to imply JPEG is encoded in some native output color space, ready for display. That happens to be close to sRGB in most modern LCDs, but not really sRGB. The ideal would be to include an I...
by rnbc
2011-08-06T16:21:12-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Generating final images from HDR data

Hello again. Here I'll give an example of how to process a file containing high dynamic range image data into a final image, ready for display, by using both pfstools and imagemagick. To generate the high dynamic range data you'll need a few exposures of the same scene, and I recommend reading the m...
by rnbc
2011-07-27T18:16:03-07:00
Forum: Digital Image Processing
Topic: JPEG noise, a comparison study
Replies: 5
Views: 19154

Re: JPEG noise, a comparison study

I'll try to. Perhaps I can write an article detailing the concepts, and with pointers, so that anyone willing can understand it. I wrote an article about this issues a few years ago in portuguese. Let's see what I can come up with! BTW, the reason to use gamma 2.0 is that shot noise grows with the s...
by rnbc
2011-07-27T17:57:25-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Re: Does Image Magick have Tonemapping operators?

Yes anthony, I won't forget and will post a full example, from source images to final, detailing the full pipeline. Just give me a few days ;)

I did it, that's why I'm saying it can be done. Just have to dig around a bit, and don't have the time right now.
by rnbc
2011-07-26T15:28:00-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Re: Does Image Magick have Tonemapping operators?

ssilk, you're quite right: I also tried pfstools in windows a few months ago, and never managed to get everything working, so I ended up with a Linux setup. May I suggest a virtual machine? Performance impact shouldn't be large since this programs are command line, and don't use any specific hardwar...
by rnbc
2011-07-26T06:55:01-07:00
Forum: Digital Image Processing
Topic: Does Image Magick have Tonemapping operators?
Replies: 64
Views: 172851

Re: Does Image Magick have Tonemapping operators?

Answering the original post: as mentioned, there is already a set of tools, under the name PFSTools (pfstmo, etc...) to deal with HDR images. It would be impossible to properly implement some of those tonemapping operators in ImageMagick because they rely on absolute luminance values. Either you wou...
by rnbc
2011-07-25T11:34:18-07:00
Forum: Digital Image Processing
Topic: JPEG noise, a comparison study
Replies: 5
Views: 19154

Re: JPEG noise, a comparison study

My conclusion at the time was that JPEG when used without chroma subsampling and 100% quality is perfectly ok for high quality image transmission and evaluation, since the noise introduced is on the same level as good image sensors and 8 bit encoding itself.
by rnbc
2011-07-25T11:24:42-07:00
Forum: Digital Image Processing
Topic: JPEG noise, a comparison study
Replies: 5
Views: 19154

JPEG noise, a comparison study

Since the use of JPEG as a proper method of transmission for high quality image evaluation recently arose I think it would be interesting to share some results I got in the past concerning JPEG noise under various quality settings and chroma subsampling settings: http://farm7.static.flickr.com/6013/...
by rnbc
2011-07-22T03:46:39-07:00
Forum: Digital Image Processing
Topic: simple auto-cropping of photos?
Replies: 12
Views: 42618

Re: simple auto-cropping of photos?

Likewise for high key images one can use the "center of blacks".

Now, one question: a simple way of sorting images in 3 categories?

- low key - use center of blacks
- high key - use center of whites
- without a key / normal - use center of edges

Extra ideas?...
by rnbc
2011-07-22T03:36:34-07:00
Forum: Digital Image Processing
Topic: simple auto-cropping of photos?
Replies: 12
Views: 42618

Re: simple auto-cropping of photos?

The method proposed by fmw42 fails miserably with portraits containing textured backgrounds in focus... but I can't come up with another simple one. Apart from that it seems pretty damn good. For relatively dark photos, low key style, you can simple choose the brightest spots as the center An interm...
by rnbc
2011-07-21T21:11:27-07:00
Forum: Digital Image Processing
Topic: Image resizing with LCD sub-pixel awareness (aka ClearType)
Replies: 18
Views: 68469

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

It just occurred to me you can also combine both methods, Point and Lanczos, in the final step. This is again not fool proof, requiring horizontal blur sometimes, so for general use, not requiring human evaluation of the results, I still think the method I stated in the previous post is the best. Th...
by rnbc
2011-07-21T20:56:26-07:00
Forum: Digital Image Processing
Topic: Image resizing with LCD sub-pixel awareness (aka ClearType)
Replies: 18
Views: 68469

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

Hello all! Jason, your method, which I saw a few hours after starting experimenting myself, basically eliminates color fringing. I'm not so sure it increases perceived resolution. In fact it may decrease it a little bit. An improvement still over no-lcd-aware rendering imho. Meanwhile I found a way ...
by rnbc
2011-07-21T03:09:19-07:00
Forum: Digital Image Processing
Topic: Image resizing with LCD sub-pixel awareness (aka ClearType)
Replies: 18
Views: 68469

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

Hi anthony! As you said the first convolve is there only to add horizontal blur if needed, otherwise it's useless. Depth 16 is critical for gamma 0.5 followed by gamma 2.0, or otherwise ugly posterization will occur. 8 bits is far from enough for a transformation as aggressive as y=x^2 followed by y...