DVDPLOT-Plot the data in one file against the data in another

Usage:

dvdplot image image2 xlow xhigh low high autoscale

Description:

DVDPLOT (Data Versus Data PLOT) plots the data from the main array in one structure against the data in the corresponding elements of the main array in another structure. It was first written to help with linearity tests (plotting data from an image with high count rates against a similar image with lower count rates).

The Y value for each point is the pixel value from IMAGE and the X value is the value of the corresponding value from IMAGE2.

The images must have identical dimensions.

Parameters:

IMAGE

Y-value image.

IMAGE2

X-value image.

XLOW

XLOW and XHIGH specify the limits in X of the plot. They are values in the same range as the data range as the main array in IMAGE2. If WHOLE is set, XLOW is set to the lowest data value in IMAGE2.

XHIGH

XLOW and XHIGH specify the limits in X of the plot. They are values in the same range as the data range as the main array in IMAGE2. If WHOLE is set, XHIGH is set to the highest data value in IMAGE2.

LOW

LOW and HIGH specify the limits in Y of the plot. They are values in the same range as the data range as the main array in IMAGE. If AUTOSCALE is set, LOW is set to the lowest data value in IMAGE for which the corresponding IMAGE2 pixel is in the range XLOW..XHIGH.

HIGH

LOW and HIGH specify the limits in Y of the plot. They are values in the same range as the data range as the main array in IMAGE. If AUTOSCALE is set, HIGH is set to the highest data value in IMAGE for which the corresponding IMAGE2 pixel is in the range XLOW..XHIGH.

WHOLE

WHOLE has the effect of setting XLOW and XHIGH (the x-limits of the plot) to the extreme data values in IMAGE2. The result is that the plot range in X is such as to cover all the pixels in the image.

AUTOSCALE

The XLOW and XHIGH parameters (or, alternatively, the WHOLE keyword) select the X-range of the plot and hence the pixels that may be plotted. The LOW and HIGH parameters then limit the Y-range of the plot. The AUTOSCALE keyword has the effect of setting LOW and HIGH to the extreme values of the pixels delimited by XLOW and XHIGH. Which is a complicated way of saying it scales the plot so all the points fit in it.

HARDCOPY

Normally, DVDPLOT produces a plot on the current soft plot device - selected using the SOFT command. If the HARDCOPY keyword is set, the plot is made on the current hard copy plot device - selected using the HARD command. Normally, only a plot file is produced and this must be explicitly sent to the hardcopy device once DVIPLOT has finished.

Source comments:

 D V D P L O T

 Routine name:
    DVDPLOT

 Function:
    Plots the data in one data array against the data in another.

 Description:
    DVDPLOT (Data Versus Data PLOT) plots the data in the main data
    array in one Figaro structure against the corresponding data elements
    of the main data array in another structure.  This was originally
    written to help with linearity tests (where data in an image taken
    at a low data rate could be plotted against one taken at a higher
    data rate), but may have other applications.

 Usage:
    DVDPLOT IMage IMAGE2 XLow XHigh LOw HIgh AUtoscale

 Parameters:
    IMAGE     (Character) The name of the first structure.  It is this
              structure whose data is plotted against the data in IMAGE2,
              so its data values form the Y values of the plotted points.
    IMAGE2    (Character) The name of the second structure.  Its data
              values form the X values of the plotted points.
    XLOW      (Numeric) The low end of the data range plotted in X (i.e.
              the lower limit for the data in IMAGE2).
    XHIGH     (Numeric) The high end of the data range plotted in X (i.e.
              the upper limit for the data in IMAGE2).
    LOW       (Numeric) The low end of the data range plotted in Y (i.e.
              the lower limit for the data in IMAGE).
    HIGH      (Numeric) The high end of the data range plotted in Y (i.e.
              the upper limit for the data in IMAGE).

 Keywords:
    WHOLE     If set, XLOW and XHIGH will be set to the limits
              of the data in IMAGE2.
    AUTOSCALE If set, LOW and HIGH will be set to the limits
              of the data in IMAGE.
    HARDCOPY  If set, a hard copy plot will be produced.

 User variables used:
    HARD      (Character) PGPLOT specification for hardcopy plot device
    SOFT      (Character) PGPLOT specification for softcopy plot device

 Error information:  Ignored.

 Quality information:  Handled using flagged values.

 Keith Shortridge, AAO