Select by color
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| Select by color | Bruno Silva de Oliveira | 02 Nov 06:56 |
| b14e81f00511060756j7c22cd3d... | 07 Oct 20:17 | |
| Select by color | Bruno Silva de Oliveira | 06 Nov 20:27 |
| Select by color | Joao S. O. Bueno Calligaris | 07 Nov 00:38 |
Select by color
Hi everyone!
I'm new in the list, but I think a can ask some things...
Does anybody knows how the select by color, or more precisely, the threshold works. How does the GIMP makes the selection using the threshold interval and how does this threshlold works in the tree channels (R,G and B)?
I'm running a windows version, and I don't get the source code...
Thanks a lot, people!
--
/**
* Bruno Silva de Oliveira
* http://bsoliveira.cjb.net/
*/
Select by color
Well, that was exactly what I tought... if the threshold is zero,
only the selected colour will be selected.
But what about a RGB with R=50, G=110 and B=220, and a threshold of
10? The colour range will be something like R=40-60, G=100-120 and
B=210-230 ?
I'm trying to implement an algorithm that does almost the same of the
select-by-colour. I'm processing images taken from a microscope (I'm
not sure about how do you spell this!) where are two kinds of
structures, one painted of yellow and the other of red. I need to make
a code for measuring the percentage of yellow, red and the space
unpainted in the picture...
I've already tried the steps I told you above, without success...
Do you (or anybody!) have some idea?
Thanks a lot!
[]'s
Bruno.
On 11/6/05, michael chang wrote:
On 11/2/05, Bruno Silva de Oliveira wrote:
Hi everyone!
I'm new in the list, but I think a can ask some things...
Does anybody knows how the select by color, or more precisely, the threshold works. How does the GIMP makes the selection using the threshold interval and how does this threshlold works in the tree channels (R,G and B)?
I'm not sure I _fully_ understand it, but I believe I get the gist of the function. When you select-by-colour, the colour under the pixel is selected, and all the pixels of the same colour are selected. If the threshold is zero (or something like that), then only the pixels with the exact same RGB values are selected, and as you increase the threshold, it will get further away from that colour.
For example, if you had a gradient that went from black to green, and you clicked on the greenest part of the gradient with select by colour, then notice how the amount you select increases as you increase the threshold.
I don't know about it from a mathimatical perspective.
If you use windows, have you considered looking at the gimpwin-users mailing list?
--
~Mike
- Just my two cents
- No man is an island, and no man is unable.
--
/**
* Bruno Silva de Oliveira
* http://bsoliveira.cjb.net/
*/
Select by color
On Sunday 06 November 2005 05:27 pm, Bruno Silva de Oliveira wrote:
Well, that was exactly what I tought... if the threshold is zero, only the selected colour will be selected. But what about a RGB with R=50, G=110 and B=220, and a threshold of 10? The colour range will be something like R=40-60, G=100-120 and B=210-230 ?
I'm trying to implement an algorithm that does almost the same of the select-by-colour. I'm processing images taken from a microscope (I'm not sure about how do you spell this!) where are two kinds of structures, one painted of yellow and the other of red. I need to make a code for measuring the percentage of yellow, red and the space unpainted in the picture...
I've already tried the steps I told you above, without success...Do you (or anybody!) have some idea?
Thanks a lot!
Hi Bruno - I do not remeber right now, but I even docuemtend it on a GIMP material I wrote once. It is somethign pretty obvious, and I remeber at the time asking on #GIMP if the algotithim hada name - it has - I will check for it as son as I can and forward to you (and to the list)
JS
->
[]'s
Bruno.
On 11/6/05, michael chang wrote:
On 11/2/05, Bruno Silva de Oliveira wrote:
Hi everyone!
I'm new in the list, but I think a can ask some things...
Does anybody knows how the select by color, or more precisely, the threshold works. How does the GIMP makes the selection using the threshold interval and how does this threshlold works in the tree channels (R,G and B)?
I'm not sure I _fully_ understand it, but I believe I get the gist of the function. When you select-by-colour, the colour under the pixel is selected, and all the pixels of the same colour are selected. If the threshold is zero (or something like that), then only the pixels with the exact same RGB values are selected, and as you increase the threshold, it will get further away from that colour.
For example, if you had a gradient that went from black to green, and you clicked on the greenest part of the gradient with select by colour, then notice how the amount you select increases as you increase the threshold.
I don't know about it from a mathimatical perspective.
If you use windows, have you considered looking at the gimpwin-users mailing list?
-- ~Mike
- Just my two cents
- No man is an island, and no man is unable.--
/**
* Bruno Silva de Oliveira
* http://bsoliveira.cjb.net/
*/
