Search found 42 matches

by joew
2013-10-25T03:42:07-07:00
Forum: Users
Topic: Cleaning up jpeg artefacts with Imagemagic?
Replies: 3
Views: 1580

Re: Cleaning up jpeg artefacts with Imagemagic?

How can I upload such an image?
by joew
2013-10-24T04:24:39-07:00
Forum: Users
Topic: Cleaning up jpeg artefacts with Imagemagic?
Replies: 3
Views: 1580

Cleaning up jpeg artefacts with Imagemagic?

Hello, I have scanned a bunch of documents, which I'd like to run through OCR and archive. Unfortunately, the scanner supports only high jpeg compression, so I got lots of artefacts. I searched the web for methods to remove those artefacts with imagemagic. But I found only a guide for GIMP ( http://...
by joew
2013-08-23T03:39:17-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

"-set colorspace RGB -colorspace sRGB" The first declares the colorspace to be RGB. The second means "If not already sRGB, convert the pixel values to sRGB." Thus the conversion will occur. "-set colorspace sRGB -colorspace sRGB" The first declares the colorspace to be sRGB*. The second means "If n...
by joew
2013-08-22T13:03:42-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

Many text processing applications allow you to specify the language, but many don't force you to. I'm not about forcing people to do the specification. I'm about the ability to be able to do so. As snibgo states, the obvious and straightforward way to do the specification is illegal syntax. The def...
by joew
2013-08-22T08:31:03-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

Two correct syntaxes are: convert -size 100x100 xc:#bebebe -set colorspace RGB -colorspace sRGB 5.png convert -size 100x100 xc:#bebebe -set colorspace sRGB -colorspace sRGB 6.png This seems wired to me. The drawings are done with undefined colorspace. With such a syntax, IM would rightfully do diff...
by joew
2013-08-21T16:02:46-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

Thanks for the link. See the very old (and now inaccurate for current IM) discussion at http://www.imagemagick.org/discourse-server/viewtopic.php?f=2&t=15955 . The author has created images that exploit a problem that (surprise, surprise) his software cures. Well, good for him. I can't find anythin...
by joew
2013-08-21T15:13:30-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

Ugh. I don't like subjective results at all. If the result looks different to different people, then I can just as well use a deterministic and correct algorithm. That's fair enough. I mostly make images for people, not machines, so what they look like is (for me) of prime importance. OTOH, you sai...
by joew
2013-08-21T14:55:53-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

I'd have expected that 1.png is identical to 3.png while 2.png is identical to 4.png. It depends upon what version of IM you are using. I don't recall you ever specified. See snibgo's comment earlier about changes in IM colorspace handling or see http://www.imagemagick.org/discourse-server/viewtopi...
by joew
2013-08-21T09:14:45-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

When I say "I do something", it doesn't mean everyone else should. As long I don't have a clue by myself, I tend to look what other people do 8) http://www.imagemagick.org/Usage/resize/#resize_colorspace says resizing should be done in linear RGB. Yes, I'm aware of that. I'm not convinced by the ea...
by joew
2013-08-21T07:54:28-07:00
Forum: Users
Topic: unsharp parameters: GIMP -> IM
Replies: 17
Views: 20354

Re: unsharp parameters: GIMP -> IM

http://redskiesatnight.com/2005/04/06/s ... ge-magick/ suggests to use sigma=sqrt(radius) when radisu is bigger than 1.
by joew
2013-08-21T03:52:44-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

You need linear colorspace to do manipulations, don't you? It depends. I do most of my work, including resizeing, in sRGB. I do colour-balancing (of raw photos) in linear RGB. I do some processing in CIELab. http://www.imagemagick.org/Usage/resize/#resize_colorspace says resizing should be done in ...
by joew
2013-08-20T14:46:02-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

That's it; you've got it. Not really. There are still lots of unanswered questions. All this is very confusing, and very badly documented AFAICS. What is when the original image has an attached profile? In this case the -colorspace settings seem to be ignored sometimes, but are still attached to th...
by joew
2013-08-20T03:45:12-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

IM v6.7.8 is an old version, so an upgrade might help. If you put up your image and full command, someone can test on more recent versions. If you can't put up the image, at least do a "identify -verbose" and paste the results here between [ code ] and [ /code ]. The problem is neither an old versi...
by joew
2013-08-19T06:34:54-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

holden wrote:If the images look fine on your monitor but print too dark that's most likely a hardware (monitor) calibration issue.
It is much darker than the original photo on the monitor, too. So the problem must be somewhere in the processing.
by joew
2013-08-17T03:34:06-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 11290

Re: From sRGB to CMYK and gamma?

This is perl, is it? I don't know perl, so don't know exactly what your code is doing. However, I note that you need the equivalent of the command-line options "-colorspace RGB" and "-colorspace sRGB". These are very different to the options "-set colorspace RGB" and "-set colorspace sRGB", and per...