PK D - Peak search - output to Document file

PURPOSE

Searches for local peaks in a picture. Places location in a SPIDER Document file.

SEE ALSO

PK	[Peak search]
PK 3	[Peak search - 3D]
PK C	[Peak search - Center of gravity]
PK D	[Peak search - output to Document file]
PK DC	[Peak search - Center of gravity, output to Document file]

USAGE

.OPERATION: PK D [x],[y],[pk],[ratio],[xp],[yp],[pkp]

[The first three optional output parameters (in this example [x],[y],[pk]) specify registers that are to receive the sub-pixel coordinates and the value of the largest peak found in this operation. The peak location is

expressed relative to the location of SPIDER's center if the image. The 4th register (here [ratio]) contains the ratio of the first peak relative to the peak # specified for that ratio (option: ORIGIN OVERRIDE). The 5th & 6th registers (here [xp],[yp]) return the sub-pixel coordinates according to a 9-point parabolic fit, and the last register (here [pkp] here) contains the value of that maximum.]

.INPUT FILE: PIC001
[Enter the name of the image file.]

.ENTER # OF PEAKS,CENTER ORIGIN OVERRIDE (0/1): 12, 0
[Enter the number of peaks to be searched for. If an origin position other than at the picture's center (NX/2 + 1, NY/2 + 1) is desired, enter '1' in the second posiposition. The system will then allow you to enter the x,y coordinates of the origin to be used.]

If the option "CENTER ORIGIN OVERRIDE" is specified, Spider asks for the next two specifications:

.NEW ORIGIN COORDINATES: 1, 1
[Enter the new origin coordinates.]

.ENTER PEAK NUMBER FOR RATIO: 1
[Enter the number of the peak relative to which the heights of the other peaks are calculated. This ratio is printed out and listed in the document file along with the other parameters of the peaks.]

.DOCUMENT FILE: DOC001
[Enter the name of the document file.]

[In the above example, the computer will find the 12 largest peaks. Their positions will be printed in the RESULTS file, and the value position of the largest peak will be printed to the user's terminal. In addition, the peak positions and values will be put into the temporary registers if output parameters [x],[y],[pk],[ratio],[xp],[yp],[pkp] are specified, and written into the document file. The registers can be used as input to a subsequent 'SH' (SHIFT) operation.

NOTES

1. This routine does not find "maximum" location when image has plateaus. It may find the "last" value along the plateau. To overcome this use low pass filtration first.

SUBROUTINES

SPEAK, SPEAKC

CALLER

UTIL1