Search found 90 matches

by HugoRune
2009-08-23T15:01:17-07:00
Forum: Users
Topic: Fun with sobel - Neon Effect - Thick Edge Detection
Replies: 31
Views: 131629

Re: Fun with sobel - Neon Effect - Thick Edge Detection

Yes, we are on the same page (sorry for the pun). I started working on my whiteboard script, but posted something before continuing with the detection of the border (hough transform) corners and the auto aspect ratio. I found a similar paper by the same authors, http://research.microsoft.com/en-us/...
by HugoRune
2009-08-23T09:33:14-07:00
Forum: Users
Topic: Fun with sobel - Neon Effect - Thick Edge Detection
Replies: 31
Views: 131629

Re: Fun with sobel - Neon Effect - Thick Edge Detection

Please post your Hough transform solution when finished. Many people have been asking for something like that. I have a working implementation for the perspective correction with hough transform, using python and openCV. It is a mess though. I want to release that after I cleaned it up a bit. Still...
by HugoRune
2009-08-22T19:24:38-07:00
Forum: Users
Topic: Fun with sobel - Neon Effect - Thick Edge Detection
Replies: 31
Views: 131629

Fun with sobel - Neon Effect - Thick Edge Detection

I have been experimenting with the sobel operator, after the helpful tips from Fred and Anthony. My goal here was to detect only thick edges and ignore small-scale variations. For example, I have a photo of a text document. I want an edge image with only the border of the document, not the text. htt...
by HugoRune
2009-08-22T16:18:35-07:00
Forum: Bugs
Topic: weird behavior with contrast-stretch
Replies: 3
Views: 9082

Re: weird behavior with contrast-stretch

curious! try similar operations with -linear-stretch and see what happens? Anthony and I have been studying both for a long time and Anthony hopes to rewrite something later this year to have more functionality and work in a better manner. I could not reproduce this behaviour with linear-stretch. (...
by HugoRune
2009-08-22T16:01:12-07:00
Forum: Users
Topic: using a sobel operator - edge detection
Replies: 56
Views: 121407

Re: using a sobel operator - edge detection

very nice work. I have a script, morphology, that has many different filters for both binary and grayscale/color images that Anthony and I put together. Yeah, that is were I got the dilate for imagemagick. It looks very impressive. But adapting the grayscale operators for windows will be a project ...
by HugoRune
2009-08-22T06:46:33-07:00
Forum: Bugs
Topic: weird behavior with contrast-stretch
Replies: 3
Views: 9082

weird behavior with contrast-stretch

I came upon some weird behaior with -contrast-stretch, not sure if it is a bug: ImageMagick 6.5.4-10 2009-08-08 Q16 This is the original image: http://img256.imageshack.us/img256/6452/additivecolorpng01.th.jpg convert AdditiveColor.jpg -contrast-stretch 0%, 21% test.png http://img15.imageshack.us/im...
by HugoRune
2009-08-22T05:51:49-07:00
Forum: Users
Topic: using a sobel operator - edge detection
Replies: 56
Views: 121407

Re: using a sobel operator - edge detection

some experiments with generating a mask with all positive pixels and one with all negative pixels of a laplacian, then dilating them and finding all pixels that are in both masks (these should be the zero-crossings) Then some filtering of close-to-zero values to exclude weak edges (low-variance filt...
by HugoRune
2009-08-21T18:17:00-07:00
Forum: Users
Topic: Batch process page images for OCR
Replies: 14
Views: 28713

Re: Batch process page images for OCR

# convert test1.tif -scale 4326x1\! -depth 16 a.txt # grep rgb\(5 a.txt I am not sure how reliable searching for "rgb(5" is. But if you throw a "-contrast-stretch 0" in there: convert test1.tif -depth 16 -scale 4326x1\! -contrast-stretch 0 a.txt Then it should work with a grep &...
by HugoRune
2009-08-21T15:44:00-07:00
Forum: Users
Topic: using a sobel operator - edge detection
Replies: 56
Views: 121407

Re: using a sobel operator - edge detection

As reference, the DOG says to use a second gaussian that is larger than the first. (subtract larger from smaller) So I had assumed, but not investigated yet the need for the laplacian to be bigger than the gaussian. That is a very god point! I did not even consider the size of the laplacian kernel ...
by HugoRune
2009-08-21T07:01:27-07:00
Forum: Users
Topic: Batch process page images for OCR
Replies: 14
Views: 28713

Re: Batch process page images for OCR

Another option: If the pages all have the same format and size, and the only difference is their alignement in the scanner, then you could trim the white border. Then all your pages should be aligned the same. You can use the same method of shrinking one dimension to one pixel to trim the border, th...
by HugoRune
2009-08-21T06:10:06-07:00
Forum: Users
Topic: using a sobel operator - edge detection
Replies: 56
Views: 121407

Re: using a sobel operator - edge detection

Interesting. I do not fully understand how a DOG approximates a LOG, but I still have to read the references cited in the wikipedia article. My own attempts at building a LOG edge detector with zero crossing: first, laplacian of gaussian: convert Flowers_before_difference_of_gaussians.jpg -blur 0x5 ...
by HugoRune
2009-08-20T19:08:10-07:00
Forum: Bugs
Topic: -colorspace CMYK -blur fails silently
Replies: 4
Views: 12151

Re: -colorspace CMYK -blur fails silently

magick wrote:We can reproduce the problem and will have a patch available within the next day or two. Thanks.
That's great, thanks!
by HugoRune
2009-08-20T19:01:09-07:00
Forum: Bugs
Topic: -colorspace CMYK -blur fails silently
Replies: 4
Views: 12151

Re: -colorspace CMYK -blur fails silently

interesting, mine does not produce a file (Version: ImageMagick 6.5.4-10 2009-08-08 Q16) Nevertheless, your output is wrong too: the Black channel is not blurred, but somehow distorted, mostly zero with a few horizontal lines. I tried to reproduce how it is supposed to look, but could not do it with...
by HugoRune
2009-08-20T16:49:20-07:00
Forum: Bugs
Topic: -colorspace CMYK -blur fails silently
Replies: 4
Views: 12151

-colorspace CMYK -blur fails silently

i did some experiments manipulating images in the CMYK space, and came upon the following: convert logo: -colorspace CMYK -channel CMY -blur 0x10 test.png this works as expected, producing an image where the colors are blured but black is not convert logo: -colorspace CMYK -channel K -blur 0x10 test...
by HugoRune
2009-08-18T18:59:54-07:00
Forum: Users
Topic: using a sobel operator - edge detection
Replies: 56
Views: 121407

Re: using a sobel operator - edge detection

It is certainly true that depending one the situation one may want to multiply the kernel with different values. But looking at your examples it seems like this can be easily acomplished by using -evaluate multiply afterwards. If the kernel is properly normalized to prevent clipping, you can always ...