NAME

wfixup -- Interpolate in the X direction over bad pixels of WFPC images.

USAGE

wfixup infile inmask outfile maxgap fillval

DESCRIPTION

This task takes an input image and its data quality file, checks for pixels been flagged "bad" in the data quality file and does a simple linear one-dimensional interpolation over these bad pixels. The result is a cosmetically better image when displayed but may not be precise enough for scientific merit.

Here is how the task works: In every row of an image, if one or more contiguous pixels have a data quality value which is specified as undesirable (see below), the two "good" points at the two ends of these pixels will be used to carry out a simple linear interpolation. For example, if pixels 4, 5, 6, are bad, pixel 3 has a value of 10, and pixel 7 has the value of 12, then pixels 4, 5, 6, will be filled with the values of 10.5, 11, and 11.5, respectively.

You can specify which types of pathologies are to be rejected by setting various flags in the `dqpar' pset. For example, setting `rsbit = yes' means all input values that suffered Reed-Solomon errors are "bad" and the task wfixup will interpolate over these pixels.

Sometimes there are long stretchs of bad pixels, or there is only one end point (i.e., the bad pixels are at the beginning or end of the row). In these situations you may not want to do the linear interpolation but instead just populate these pixels with some pre-determined fill value. This can be done by specifying the maximum length of contiguous bad pixels (parameter maxgap), so when the stretch of bad pixels is longer than this number, they will be filled with the value specified in the parameter fillval. If fillval is equal to INDEF, original pixel values are preserved in the bad pixels. In the case of only one (or none) end point being available, (i.e. the bad pixels are at the beginning or end of the row), it will be treated the same as if the maxgap limit were exceeded.

PARAMETERS

infile = "" [string]

Name of the input file template. Input files must be two-dimensional and of REAL data type.

inmask = "" [string]

Name of the input data quality file template. Input data quality file must be 2-dimensional and contain SHORT data type. Each input file should have one corresponding data quality file.

outfile = "" [string]

Name of the output data file template. Each output file should have one corresponding output data quality file. If the the value of this parameter is NULL, the input data file will be updated.

maxgap = [int, min = 1]

Maximum number of contiguous bad pixels allowed in a row. If there are more bad pixels than this number, these pixels will be filled with the fill value specified in the next parameter.

fillval = INDEF [real]

Fill value used to fill the pixels which are in a long stretch of bad data. If this parameter has the value of INDEF, original data values are kept.

(dqpar = "") [pset]

Pset name for DQF parameters.

EXAMPLES

1. Interpolate over the bad columns in the WFPC image in.r6h using the file in.b6h as a data quality mask file and create the output file new.r6h. Use a gap width of 10.

wf> wfixup in.r6h in.b6h new.r6h maxgap=10 fillval=INDEF

2. Same as above but only do the second group. In this case, the output image will only have one group.

wf> wfixup in.r6h[2] in.b6h[2] new.r6h maxgap=10 fillval=INDEF

3. An unlikely but legal example: use one subsection of a data quality file's third group to fixup one subsection (must have the same size) of an image's second group.

wf> wfixup jc.hhh[2][1:95,1:95] m.hhh[3][2:96,2:96] new maxgap=10 fillval=INDEF

REFERENCE

BUGS

SEE ALSO