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Re: image data extraction [message #2186 is a reply to message #2181]

Fri, 03 June 1994 06:39

landers
Messages: 45
Registered: May 1993

Member

Finding image data along a line...

This just picks points from the image. It doesn't do any image
interpolation or anything like that. Just finds the closest x,y to the
line.

Just some code fragments I sucked out of one of my codes:

; Line endpoints are (x1,y1), (x2,y2) (these are indices into the image)
; image size is (Mx,My)

; There are two methods here. The first works better for more
; horizontal cuts, the second for more vertical. You could put a test
; on the slope of the line, and choose your method accordingly.

;;;;;;;;;;;;;;;;;;
; Horizontal cuts:
; first figure out how many points you want to grab between the ends.

Nx = Abs( x2 - x1 ) > 1
Ny = Abs( y2 - y1 )

; find the x and y indices into the image along the cut
; get one point for every x pixel in the cut line, and figure the
; corresponding y points

thex = Long( Lindgen( Nx + 1 ) + x1 )
they = Long( Lindgen( Nx + 1 ) * Float(Ny)/Nx + y1 )

image_line = image( they * Mx + thex )

;;;;;;;;;;;;;;;;
; Vertical cuts:

Nx = Abs( x2 - x1 )
Ny = Abs( y2 - y1 ) > 1

; get one point for every y pixel in the cut line

thex = Long( Lindgen( Ny + 1 ) * Float(Nx)/Ny + x1 )
they = Long( Lindgen( Ny + 1 ) + y1 )

image_line = image( they * Mx + thex )

;Dave

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[Message index]

		Re: image data extraction By: sterner on Fri, 03 June 1994 10:30
		Re: image data extraction By: landers on Fri, 03 June 1994 06:39
		The cubic keyword in interpolate By: sterner on Mon, 13 June 1994 06:34

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