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imdisp xray.xspatial



imdisp -- pixel display of photons in the specified regions of an image


imdisp image


imdisp displays the pixel values of an array of photons in the specified source regions. Exposure filtering can be applied if a PLIO exposure mask and a threshold value are supplied by the user. The nrows and ncols parameters determine the size of the display on the screen as well as the dimensions of the table. The image is blocked (compressed) to fit into a display buffer of dimensions ncols by nrows . The right and bottom sides of the image are clipped to fit into this display buffer, if necessary. The display also contains information about the blocking factors, scale, bias, and flip orientation.

Note that the width of each displayed pixel is determined by the data type of the file (e.g. int data is displayed using a "%5d " format, while float data is displayed using a "%7.2f " format) so that the number of columns to be displayed may have to be adjusted (or the screen size made larger if a re-sizable window is being used) to avoid overflowing the screen size. In addition, scale and bias can be used to scale the blocked data before being displayed to avoid overflow.

A table file can be created that contains the same information as the display. Column names are c<xxx>, where <xxx> is the pixel number of the start of each column. For example, a 10x10 image with 3 columns will have column names c1, c4, and c7. The header of the table contains the x and y blocking factors, scale, bias, and flip orientation, as well as mask and exposure information.

The display (and table) can be flipped so that the last row is displayed first. Visually, the display will look "correct", that is, north will be up for Einstein images. However, in such a case, the first row of the table will be the last row of the image data.

If the image is a large-dimension qpoe (e.g., HRI), it is much faster to block the image using the qpoe block filter than to have the task do the blocking to fit the display. That is:

		imdisp "hri.qp[block=85]" ncols=16 nrows=16

will be much faster than

		imdisp hri.qp ncols=16 nrows=16

The display will be the same, except that the block factor will be displayed as 1 in the former case, and as 85 in the latter.


image = "" prompt = image file to display

The image data file. This can be any IRAF image file, including X-ray QPOE files. In the latter case, all QPOE filters are available to the user, although it is not recommended that the MASK specifier be used directly in the QPOE filter specification. Note, however, that imdisp only displays a 1-D or 2-D section of an image. Images of dimension greater than two must use the IRAF section specification to reduce the dimensionality of the data to be displayed.

(region = "") [string]

The ASCII region descriptor or pixel mask file name.

(exposure = "NONE") [string]

The PLIO mask containing exposure information for the specified image. If the null string is input, the name will be the same root as the image file with a "" extension. If "NONE" is input (the default), no exposure filtering is performed.

(expthresh = 0.) [real]

The percentage of total exposure required for a given pixel to pass the exposure filter, (if an exposure mask is present). For example, if expthresh is 50.0, then only pixels whose exposure time is >= 50% will be used. An exposure threshold of 0% allows all photons to pass the exposure filter.

(scale = 1.) [real]

The multiplicative scale factor to be applied to the blocked data. This is useful if the data overflows the format of the display.

(bias = 0.) [real]

The additive bias to be applied to the blocked data.

(flip = yes) [boolean]

Boolean flag that determines whether the data is displayed in reverse row order. If flip is true, the data is displayed (and also entered into the table) such that the first row of data is at the bottom of the display (table). This is how data is normally displayed by ximage and corresponds to the fact that the IRAF coordinate origin is in the lower left. However, when flip is true, the first row of table data is actually the last row of data from the image.

(ncols = 12) [int]

The number of columns to display. The image is blocked (compressed) in the first dimension to fit this display size.

(nrows = 12) [int]

The number of rows to display. The image is blocked (compressed) in the second dimension to fit this display size.

(disp_header = no) [boolean]

Boolean flag that determines whether the X-ray header information is displayed (if such information is available).

(table = "NONE") [string]

Name of the STScI table file to create. If the null string is input, the table file name defaults to the root of the qpoe file with a "" extension. The extension can be omitted in the specification. The table file contains ncols columns of data, each column containing nrows values. If the string "NONE" is input (the default), no table file is created.

(clobber = no) [boolean]

Boolean flag specifying whether or not the table file can be overwritten, if it already exists.


1. Display the image file i296 through a mask consisting of the following regions:


Mask the data through an exposure mask with the threshold of exposure set at 99 percent. Create a table named

cl> imdisp i296 "" 99.0 "" nrows=12 ncols=12

image:		i296
mask_name:	in memory &
mask_type:	region & exposure
ref_file:	i296
xdim:		1024
ydim:		1024
scale:		none
regions:	ANNULUS(449.74,409.20,0.00,200.00,n=3.00) &
exposure threshold:	99.0000000

blocking factors (x,y):	85 85
scale factor:	 1.00
bias factor:	 0.00
display is flipped

    0     0     0     0     0     0     0     0     0     0     0     0 
    0     0     0     0     0     0     0     0     0     0     0     0 
    0     0     0     0     0     0     0     0     0     0     0     0 
    0     0     0     0     0     0     0     0     0     0     0     0 
    0     0     0     0   142   601    18     0     0     0     0     0 
    0     0     0   255  3561  7496  7727   392     0     0     0     0 
    0     0     0  1268  3838 13381  9062  2424     0     0     0     0 
    0     0     0   669  1925  7932  3489  1023     0     0     0     0 
    0     0     0     3   693  1340  1779   445     0     0     0     0 
    0     0     0     0   329    21     0     0     0     0     0     0 
    0     0     0     0     0     0     0     0     0     0     0     0 
    0     0     0     0     0     0     0     0     0     0     0     0 

total counts:			 69813
max value at pixel (6,6):	 13381
(pixel (1,1) is in lower left corner)

The file can be displayed using tprint.


The time required depends on the speed of the mask I/O, and is proportional to the number of photons being filtered. Also, if a region description is input rather than an already existing pixel mask, for source and/or bkgd region, the pixel mask must be created at run time. This only takes a few seconds.



Documentation on region filtering (help regions ) for a description of the spatial filter user interface.

Documentation on QPOE filtering (help qpoe ) for a description of the QPOE filter user interface.

Documentation on file extensions (help extensions ) for a description of PROS file extensions.

Documentation on coordinates (help coords ) for a description of PROS coordinate conventions.

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