mkpattern input
input
Images to create or modify. Image sections are allowed to apply a pattern
to a portion of an image.
output =
Output images when modifying input images. If no output images are
given then existing images in the input list are modified directly.
If an output image list is given then it must match in number the
input list.
pattern = constant
Pattern to be used. The patterns are:
constant
Constant value v1.
grid
A grid starting with the first pixel and going in steps of the
pattern size with value v2. Pixels between the grid have value v1.
A minimum grid size of 2 is enforced.
checker
A checkerboard with squares of the pattern size alternating between values v1
and v2 starting with v1.
coordinates
Each pixel is numbered sequentially starting with 1 with the column
dimension varying fastest.
slope
A sloped plane starting with value v1 for the first pixel and value v2 for
the last pixel in one or two dimensions.
square
A checkerboard pattern in which the size of the squares begin with
the pattern size and grow as the square of the coordinate.
option = replace
Editing option when modifying existing images. Often this is used
in conjunction with image sections to modify a part of an image.
The options are:
replace - Replace the image with the pattern.
add - Add the pattern to the image.
multiply - Multiply the pattern with the image values.
.le
size = 1
Pattern size used as described for each pattern.
WHEN CREATING NEW IMAGES
title =
Image title to be given to the images. Maximum of 79 characters.
pixtype = real
Pixel datatype of new images; one of short, integer, real, or double.
ndim = 2
Number of dimensions between 1 and 7.
ncols = 512, nlines = 512
Number of columns (first dimension) and lines (second dimension).
n3 = 1, n4 = 1, n5 = 1, n6 = 1, n7 = 1
Number of pixels in 3rd-7th dimensions
header = artdata$stdheader.dat
Image or header keyword data file. If an image is given then the image header
is copied. If a file is given then the FITS format cards are copied.
This only applies to new images. The data file consists of lines
in FITS format with leading whitespace ignored. A FITS card must begin
with an uppercase/numeric keyword. Lines not beginning with a FITS
keyword such as comments or lower case are ignored. The user keyword
output of imheader is an acceptible data file. See mkheader
for further information.
This task creates or modifies images with a choice of patterns. New images are created with the specified dimensions, datatype, and pattern. Existing images may have the pattern replace, add, or multiply the pixel values. Existing images may be modified in place or new images may be created and image sections are allowed.
For new images a set of header keywords may be added by specifying an image or data file with the header parameter (see also mkheader). If a data file is specified lines beginning with FITS keywords are entered in the image header. Leading whitespace is ignored and any lines beginning with words having lowercase and nonvalid FITS keyword characters are ignored.
This task is the simplest one for creating empty images to be used for mosaicing with imcopy and making patterns for testing display and image operators. The replace option is generally used with image sections to place constant values in regions. The multipy option is useful for making masks of the given pattern when the values are 0 and 1.
Though the patterns make sense extending to higher dimensions they are only defined in two dimensions. One dimensional images may be thought of as the first line of the two dimensional pattern. Images with dimensions greater than 2 simply repeat the two dimensional pattern into the higher dimensions. The reason for stopping at two dimensions is simplicity.
The patterns have the following precise definitions where P(i,j) is the pixel value at column i and line j, v1 and v2 are the pattern values, size is the pattern size, ncols and nlines are the number of columns and lines in the image, int is the integer function, mod is the modulus function, and sqrt is the square root function.
k = int ((i-1)/size), l = int ((j-1)/size)
ksr = int (sqrt (k)), lsr = int (sqrt (l))
slope = (v2-v1) / ((ncols+nlines-2)/size)
constant: P(i,j) = v1
grid: P(i,j) = v2 when mod(i,size)=1 or mod(j,size)=1
P(i,j) = v1 otherwise
coordinates: P(i,j) = i + j * ncols
checker: P(i,j) = v1 when mod(k,2)=0 and mod(l,2)=0
P(i,j) = v2 when mod(k,2)=1 and mod(l,2)=0
P(i,j) = v2 when mod(k,2)=0 and mod(l,2)=1
P(i,j) = v1 when mod(k,2)=1 and mod(l,2)=1
slope: P(i,j) = v1 + slope * (k + l)
square: P(i,j) = v1 when mod(ksr,2)=0 and mod(lsr,2)=0
P(i,j) = v2 when mod(ksr,2)=1 and mod(lsr,2)=0
P(i,j) = v2 when mod(ksr,2)=0 and mod(lsr,2)=1
P(i,j) = v1 when mod(ksr,2)=1 and mod(lsr,2)=1
1. Create an empty (constant value of zero) three dimensional image.
cl> mkpattern cube ndim=3 nc=100 nl=100 n3=100
2. Replace a square region of an image with the value -1000.
cl> mkpat alpha[201:250,1:50] v1=-1000
3. Put a grid pattern on an image to create a new image.
cl> mkpat dev$pix out=gridpix pat=grid op=mul v1=1 v2=0