Search found 7 matches

by RitterRunkel
2013-10-01T01:57:58-07:00
Forum: Users
Topic: Text in gray area remove gray area
Replies: 8
Views: 5393

Re: Text in gray area remove gray area

I think the problem is that the document is less grey in the background than rather black dotted/dashed. So kernel size and threshold will eliminate some of the right dots as well. If there's no other possibility to scan differently (less contrast, color, ...) it could become difficult. Since I'm no...
by RitterRunkel
2013-09-29T10:08:37-07:00
Forum: Users
Topic: How do I filter out red, white, yellow - but keep the green?
Replies: 7
Views: 7238

Re: How do I filter out red, white, yellow - but keep the gr

Looks good, and -fuzz %distance is described as well ... could be used to find all other greens, too? =)

Seems simpler than my thoughts. I was thinking at channel seperation, threshold at 50% to binary b/w and then darken the green-b/w with the inverse other two b/w ...
by RitterRunkel
2013-09-29T09:47:45-07:00
Forum: Users
Topic: Text in gray area remove gray area
Replies: 8
Views: 5393

Re: Text in gray area remove gray area

I think he wants only the text to be left in the image. Kind of an extraction/background-foreground/segmentation problem. The question is, whether his images are artificial images and the background is homogenous filled with a certain color, which could be simply set to white or transparent ... or i...
by RitterRunkel
2013-09-17T09:15:52-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 408139

Re: best downsampling method for DSLR photographs

From this thread and http://www.imagemagick.org/discourse-server/viewtopic.php?f=22&t=21415, it seems sigmoidal processing is suggested for reduce halos when enlarging, and not for reducing. That's right and that's basically where I took this idea from. But nevertheless I experimented to use it in ...
by RitterRunkel
2013-09-17T08:50:48-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 408139

Re: best downsampling method for DSLR photographs

I've heard that downsizing in no more than 50% increments at a time helps, even sharpening at each level, but that would be up for experimentation IMO. Tried it, but didn't help. Think that stepwise resizing is meant to be helpful in sharpness and detail. But my problem is more color than luminance...
by RitterRunkel
2013-09-17T07:32:02-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 408139

Re: best downsampling method for DSLR photographs

Some non-photographic images are better downsampled in RGB space, rather than the default sRGB space Already did that ... but tried your code, too, and all was fine, so I quickly figured out, what was wrong in my code. In my testing sigmoidal contrasting was left: convert x.png -colorspace RGB +sig...
by RitterRunkel
2013-09-17T05:47:32-07:00
Forum: Users
Topic: best downsampling method for DSLR photographs
Replies: 273
Views: 408139

Re: best downsampling method for DSLR photographs

Hello and thx for all the knowledge so far! I've got three questions: 1. Any news on best downsampling methods for photographs, and what exactly (which algorithm) is lohalo and nohalo, coming up in gimp? There seems to be no lohalo/nohalo-equivalent in ImageMagick, or is there? 2. I'm quite happy wi...