Line/Column Mean Intensities

This option determines the mean, rms or standard deviation of the intensity for each line and/or column within a window. This is equivalent to evaluating the marginal sums for the intensity. The data may optionally be written to file and/or plotted on a frame buffer as either a histogram or intensity bar.

Line/column means for which buffer ?

The line/column intensity means may be calculated on a list of buffers. Any valid DigImage buffer may be used.

Another buffer ? Responding yes (<Y>) allows a further buffer to be specified, while no (<N>) allows DigImage to continue.

Line/column intensity means for Window or whole Screen ?

The line/column intensity means may be calculated using a window (<W>) within a buffer, or the entire buffer (<S>).

Specify Window: Region used to evaluate line/column intensity means

The window specification submenu will be produced only if a window (<W>) is selected in the previous entry. Means will be calculated only for lines/columns lying within the window. The window is specified in the normal DigImage manner. For further details, consult [H Help] within the submenu.

Calculate intensity means for Lines, Columns or Both ?

If <L> is chosen, then the intensity mean for every line in the window or buffer will be calculated. Similarly, if <C> is chosen, the mean for every column will be calculated. Selecting <B> will calculate the mean for every column and the mean for every row.

Calculate Arithmetic mean, Root mean square or Standard deviation ?

In addition to calculating the simple arithmetic mean (A), this option is able to compute the RMS value or standard deviation for each line/column.

Name of file to write data to (blank to suppress, .DAT default extension) ?

The line/column mean data may be written to the formatted file specified by this field. The formatted output file may be suppressed by entering a blank line.

New or Append ? If the specified output file already exists, answering <N> to this question will cause the previous contents of that file to be lost, while <A> will append the new data to the existing file. If the file does not already exist, then the answer to this question will have no effect and a new file will always be created.

Plot line/column means on which buffer (-1 to suppress) ?

The line/column intensity means may be plotted on one of the frame buffers as specified by this option. A value of -1 is used to indicate that the plot is not to be produced.

{If plotting means}

Erase plot buffer first ?

Answering yes (<Y>) to this question will erase the current contents of the plot buffer before producing the line/column intensity mean plots.

{If plotting means}

Plot as an Intensity bar or a Histogram ?

The plot of the line/column mean intensity may take to form of either a an intensity bar (<I>) or a histogram (<H>). If a histogram is chosen, then the line means are plotted as a function of line number in an intensity equal to 255-8*iBuf, where iBuf is the buffer sequence number. The column means are plotted as a function of column number in an intensity equal to 127-8*iBuf. When plotting intensity bars, the user may select where the bar is positioned (see below).

{If plotting intensity bars}

Plot first line mean at which column ?

This prompt is produced only when evaluating line means and plotting them as an intensity bar. The height of the intensity bar is equal to the height of the window and its vertical position is fixed by the window. This entry specifies the horizontal position of the intensity bar. One bar two pixels in width is generated for each buffer processed. The first bar is positioned at the column specified here. The second bar is positioned in the two columns immediately to the right of the first bar, etc.

{If plotting intensity bars}

Plot first column mean at which row ?

This prompt is produced only when evaluating column means and plotting them as an intensity bar. The width of the intensity bar is equal to the width of the window and its horizontal position is fixed by the window. This entry specifies the vertical position of the intensity bar. One bar two pixels in height is generated for each buffer processed. The first bar is positioned at the row specified here. The second bar is positioned in the two rows immediately below the first bar, etc.

Parent menu

Main Menu

DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996