| particle detection - a way to speed up things? [message #56944] |
Wed, 28 November 2007 05:40  |
Ingo von Borstel
Messages: 54
Registered: September 2006
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Hi there,
I run an algorithm which tries to detect particles on image sequences.
The most time consuming operation (more than half of the processing
time) is to find the centre of all detected particles. I calculate the
centre of each particle separatedly by supplying an image where only the
i-th particle is present to "schwerpunkt2". Is there a faster way to do
this? I put the outline of the calling routine and "schwerpunkt2" below
for reference.
Best regards,
Ingo
PRO schwerpunkt2, image, xpos, ypos, img_total=img_total, dims=dims
; Procedure returns the centre of weight (xpos, ypos) of a
; 2D-array (image). In order to speed up calculation, the total of the
; supplied 2D array (img_total) and its dimensions (dims) can be
; supplied, should they already be known.
IF SIZE(image,/N_DIMENSIONS) NE 2 THEN BEGIN
MESSAGE, "Number of dimensions must be exactly two.",/CONTINUE
xpos = 0
ypos = 0
RETURN
ENDIF
IF NOT KEYWORD_SET(dims) THEN $
dims = SIZE(image,/DIMENSIONS)
IF NOT KEYWORD_SET(img_total) THEN $
img_total = TOTAL(image)
xs = dims[0] & ys = dims[1]
xvec = indgen(xs)
yvec = indgen(ys)
xpos = TOTAL(xvec * TOTAL(image,2))/img_total
ypos = TOTAL(yvec * TOTAL(image,1))/img_total
END ; schwerpunkt2
PRO detect_particles, filename, area, pos, brightness, minintbright,
maxsize, minsize
image = READ_IMAGE(filename)
; Now do proper noise reduction and particle enhancement using edge
detection, and filtering with proper structuring elements such that
particles most probable don't overlap anymore and are separated by zeros
in the image.
gray_image = enhance_image(image)
particle_image =
WATERSHED(255-gray_image,CONNECTIVITY=8,/LONG,nregions=n_par ticles)
dims =SIZE(particle_image,/DIMENSIONS)
pos = DBLARR(n_particles,2)
area = DBLARR(n_particles)
brightness = DBLARR(n_particles)
; Now determine properties of all detected particles
FOR i=0,n_particles-1 DO BEGIN
bin_thisparticle = particle_image EQ i
gray_thisparticle = particle_image * bin_thisparticle
xpos = 0 & ypos = 0
area[i-1] = TOTAL(bin_thisparticle)
brightness[i-1] = TOTAL(gray_thisparticle)
schwerpunkt2, gray_thisparticle, xpos,
ypos,img_total=brightness[i-1],dims=dims
pos[i-1,0] = xpos
pos[i-1,1] = ypos
IF area[i-1] LT minsize OR area[i-1] GT maxsize OR brightness[i-1] LT
minintbright THEN BEGIN
real_particle[i-1] = 0
gray_image *= particle_image NE i
ENDIF
ENDFOR
END ;detect_particles
--
Ingo von Borstel <newsgroups@planetmaker.de>
Public Key: http://www.planetmaker.de/ingo.asc
If you need an urgent reply, replace newsgroups by vgap.
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