| Re: 3D array imaging with different colors [message #83347] |
Fri, 01 March 2013 03:39  |
tackmeister
Messages: 5
Registered: March 2013
|
Junior Member |
|
|
Op donderdag 28 februari 2013 18:15:21 UTC+1 schreef David Fanning het volgende:
> David Fanning writes:
>
>
>
>> You seem to know what colors you want. Just find the RGB value for that
>
>> color and assign those values to the pixels you want to be that color.
>
>> Simple as that.
>
>
>
> You want something like this:
>
>
>
> a = fltarr(500,500,3) + 128
>
> color = [0, 0, 255] ; Blue
>
> a[50:99,200:249,0] = Replicate(color[0],50,50)
>
> a[50:99,200:249,1] = Replicate(color[1],50,50)
>
> a[50:99,200:249,2] = Replicate(color[2],50,50)
>
> color = [255, 255, 0] ; Yellow
>
> a[200:249,50:99,0] = Replicate(color[0],50,50)
>
> a[200:249,50:99,1] = Replicate(color[1],50,50)
>
> a[200:249,50:99,2] = Replicate(color[2],50,50)
>
> color = [255, 0, 0] ; Red
>
> a[400:449,250:299,0] = Replicate(color[0],50,50)
>
> a[400:449,250:299,1] = Replicate(color[1],50,50)
>
> a[400:449,250:299,2] = Replicate(color[2],50,50)
>
> graph = image(a)
>
>
>
> Cheers,
>
>
>
> David
>
>
>
> --
>
> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")
Hi David,
Thanks for your answer! However, I'm afraid I depicted my 'problem' too simple and/or I don't fully understand your latest comment.
The actual array I use ranges from much more than 0-400. In fact it is an intensity image, which can range from 0 to a few million counts. Each 2D array (in the 3D array) represents the intensity distribution of a different element in a sample (say Zn, Fe and Cu). Before plotting I would scale the values to give values between 0 and 255 using the bytscl function, so this makes the pixel values in the correct color range.
Now I want to create an image which shows the Zn distribution in red, Fe in green and Cu in blue, in such a way that when all three elements (Fe, Cu and Zn) are present in the same pixel, this pixel is plotted as black. When none of the elements are present in a pixel, it should be plotted as white. When only Fe and Zn are found in a pixel, but no Cu, I'd want the pixel to show the color equal to 155*green+200*red if the scaled intensity of Fe=155 and the scaled intensity of Zn=200 (does this make sense?).
In the end I'd want an image that looks like this: http://ars.els-cdn.com/content/image/1-s2.0-S000326701000154 6-gr7.jpg (this is actually an image from one of the researchers in the same group as I work in) but instead of scaling from black to white, I want it inverted but I want to keep the nice red, blue and green colors. (because I tried reversing my image array, which runs from 0-255, yet this drew the image in the pink, yellow and light blue, which I do not like very much).
If I understand your first post correctly, by using a 3D array in the image function I define the colors directly by their RGB channel, so if I want to get a different color output I'd have to manipulate RGB channel seperately and change it to the color I want? Is there a way you could suggest me to do this automatically so I get the result I'd like?
Thanks again for your fast response, and I hope to get your (or someone else's) advise again.
|
|
|
|
| Re: 3D array imaging with different colors [message #83364 is a reply to message #83347] |
Thu, 28 February 2013 09:15  |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
David Fanning writes:
> You seem to know what colors you want. Just find the RGB value for that
> color and assign those values to the pixels you want to be that color.
> Simple as that.
You want something like this:
a = fltarr(500,500,3) + 128
color = [0, 0, 255] ; Blue
a[50:99,200:249,0] = Replicate(color[0],50,50)
a[50:99,200:249,1] = Replicate(color[1],50,50)
a[50:99,200:249,2] = Replicate(color[2],50,50)
color = [255, 255, 0] ; Yellow
a[200:249,50:99,0] = Replicate(color[0],50,50)
a[200:249,50:99,1] = Replicate(color[1],50,50)
a[200:249,50:99,2] = Replicate(color[2],50,50)
color = [255, 0, 0] ; Red
a[400:449,250:299,0] = Replicate(color[0],50,50)
a[400:449,250:299,1] = Replicate(color[1],50,50)
a[400:449,250:299,2] = Replicate(color[2],50,50)
graph = image(a)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
|
|
|
|
| Re: 3D array imaging with different colors [message #83365 is a reply to message #83364] |
Thu, 28 February 2013 08:49 |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
tackmeister@gmail.com writes:
> The past few months I've been breaking my head on a particular problem. I try to create RGB images using the image function. My array to plot is three dimensional, an example image would be:
>
> a=fltarr(500,500,3)
> for i=0,499 do if i lt 300 and i gt 200 then a(i,*,0)=i
> for i=0,499 do if i lt 300 and i gt 200 then a(*,i,0)=i
> for i=0,499 do if i lt 100 and i gt 0 then a(i,*,1)=i
> for i=0,499 do if i lt 100 and i gt 0 then a(*,i,1)=i
> for i=0,499 do if i lt 500 and i gt 400 then a(i,*,2)=i
> for i=0,499 do if i lt 500 and i gt 400 then a(*,i,2)=i
>
> I plot this array using:
> graph = image(a)
>
> The problem now is that every pixel with value (0,0,0) as (R,G,B) will be plotted black. Personally, I'd prefer it if the scaling would occur from white to black instead of the other way around (by default).
>
> I tried to change the color table used, yet this doesn't work. The only thing that does help is by inverting the bytscled array, yet this inverts the entire color table and gives strange looking color. Using the tv procedure instead of the image function also doesn't help.
>
> In any case, does anyone of you have an idea how I can image my 3D array as an RGB image, scaled from white (lowest intensity) to black (highest intensity)?
Huh!? There is no color table here. You are specifying the colors
directly. If you want a pixel with a RGB value [0,0,0] to be plotted
white, then you have no choice but to change its value to [255,255,255].
A color table, ANY color table, is useless to you!
Actually, your colors are worthless to you too, since the values in the
array are ranging from 0 to 400, and color values in an RGB triple can
only range from 0 to 255.
You seem to know what colors you want. Just find the RGB value for that
color and assign those values to the pixels you want to be that color.
Simple as that.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
|
|
|
|
| Re: 3D array imaging with different colors [message #83427 is a reply to message #83347] |
Fri, 01 March 2013 06:49 |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
tackmeister@gmail.com writes:
> If I understand your first post correctly, by using a 3D array in the
> image function I define the colors directly by their RGB channel, so
> if I want to get a different color output I'd have to manipulate RGB
> channel seperately and change it to the color I want? Is there a way
> you could suggest me to do this automatically so I get the result I'd
> like?
If you just want to change the background color. Find all the pixels
that have zeros in all three color channels and change the value of
these pixels to 255 in each color channel. Do the opposite to change
white pixels to black.
I doubt this will be satisfying to you, because normally in a "mixing"
situation like this, there will be a lot of pixels that are "almost"
black (e.g., [0,1,4]). These will not be found and won't be changed.
I think it will be easier in your situation to just learn to love black
backgrounds. You will sleep better at night. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
