[SLE] OT: ImageMagick::convert -white-threshold ?
does anyone know how to use the -white-threshold option of ImageMagick::convert? /Per Jessen, Zürich -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
On Wednesday 14 June 2006 07:29, Per Jessen wrote:
does anyone know how to use the -white-threshold option of ImageMagick::convert?
/Per Jessen, Zürich
I assume you've read the docs in /usr/share/docs/packages...... I read up on the threshold value and not only don't understand it, I can't even figure why it would ever be used.... :-) -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
On Wednesday 14 June 2006 20:12, Bruce Marshall wrote:
On Wednesday 14 June 2006 07:29, Per Jessen wrote:
does anyone know how to use the -white-threshold option of ImageMagick::convert?
/Per Jessen, Zürich
I assume you've read the docs in /usr/share/docs/packages......
I read up on the threshold value and not only don't understand it, I can't even figure why it would ever be used.... :-)
As the doc says: it forces all pixels brighter than the threshold value to be white. I can see where it might be useful on a scanned image, where you have any number of shades of off-white, you'd want to have a uniform colour so they can be manipulated easier. You also have the converse --black-threshold which makes all pixels darker than the threshold value be black -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
On Wednesday 14 June 2006 14:20, Anders Johansson wrote:
On Wednesday 14 June 2006 20:12, Bruce Marshall wrote:
On Wednesday 14 June 2006 07:29, Per Jessen wrote:
does anyone know how to use the -white-threshold option of ImageMagick::convert?
/Per Jessen, Zürich
I assume you've read the docs in /usr/share/docs/packages......
I read up on the threshold value and not only don't understand it, I can't even figure why it would ever be used.... :-)
As the doc says: it forces all pixels brighter than the threshold value to be white.
I can see where it might be useful on a scanned image, where you have any number of shades of off-white, you'd want to have a uniform colour so they can be manipulated easier. You also have the converse --black-threshold which makes all pixels darker than the threshold value be black
Ah so..... i got down into the documentation and it just talked about 'threshold', losing the idea of white or black. And it seemed that it would either force pixels to go white or if not, make them black. –threshold value{green,blue,opacity}{ %} threshold the image. Create an image such that any pixel sample that is equal to, or exceeds the threshold, is reassigned the maximum intensity otherwise the minimum intensity. <---------------------------- If the green or blue value is omitted, these channels use the same value as the first one provided. If all three color values are the same, the result is a bi-level image. If the opacity threshold is omitted, OpaqueOpacity will be used and any partially transparent pixel will become fully transparent. If only a single 0 is provided, auto-thresholding will be performed. To generate an all-black or all-white image with the same dimensions as the input image, you can use. convert -threshold 65535 in.png black.png convert -threshold 0,0 in.png white.png -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
Bruce Marshall wrote:
On Wednesday 14 June 2006 07:29, Per Jessen wrote:
does anyone know how to use the -white-threshold option of ImageMagick::convert?
I assume you've read the docs in /usr/share/docs/packages......
And a lot more. :-(
I read up on the threshold value and not only don't understand it, I can't even figure why it would ever be used.... :-)
My main problem is - how is the value specified? I want to make rgb(254,254,254) and rgb(255,255,255) both white for use with '-transparent white'. I ended up reading the source - the correct formats appears to be something like 'x,x,x', but using '254,254,254' turns everything _but_ rgb[255,255,255) into 'white'. Anders Johansson wrote:
I can see where it might be useful on a scanned image, where you have any number of shades of off-white, you'd want to have a uniform colour so they can be manipulated easier.
Exactly what I need, although from a scan. /Per Jessen, Zürich -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
participants (3)
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Anders Johansson -
Bruce Marshall -
Per Jessen